yacht capsize ratio

Very nice article to explain the "numbers". Your Irwin 28 shows as an excellent coastal cruiser from the "Good Old Boat" era. She has beautiful lines to me also-proportions look right and I am a big fan of a nice sheerline as I have been spoiled by my C&C25-MkI and sisterships 27 MkI-IV/30 MkI from the 70's-early 80's. Recently sold our C&C and looking for a coastal cruiser in the 28-3o ft range and did not have this on my list of prospects. One just popped up this week locally and I definitely want to see her. Thanks again for you articles-I am sure they have been and will be helpful to other new and salty sailors. Rob

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Comparing capsize and comfort rates of boats

• Thread starter Richard Marble
• Start date Mar 16, 2004
• Forums for All Owners
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Richard Marble

Here is a list of boats to compare. I have a 1981 Hunter 27. I know from sailing my boat that it feels very stable when it is rough out. I have been comparing the capsize factor and the comfort factor of my boat with other boats. Here is what I have found."Note" anything with a capsize factor over 2 I did not do a comfort factor on as they are more able to capsize so I didn’t figure it made much difference if you were comfortable. What surprised me is that a Hunter 27’s capsize and comfort rate is right up there with a Hunter 35.5 and is better than an Islander 32!!!If your boat is not here and you want to check it go to the related link.Hunter 27 1981Capsize factor of -1.94Comfort factor - 23.39Hunter 31 1985Capsize factor - 1.9Comfort factor - 24.55Hunter 28 1986Capsize 2.21 Not acceptableHunter 30 1983Capsize factor of -1.89Comfort factor - 25.21Hunter 33 1981Capsize factor of -1.86Comfort factor - 25.56Hunter 35.5 1995Capsize factor of -1.97Comfort factor - 24.57Irwin Citation 31 1979Capsize factor of -2.09 Not acceptablePearson 31 1978Capsize factor - 2.03 Not acceptableAllied Seawind 30 1965Capsize factor of - 1.62Comfort factor - 36.86Bristal 32 1966Capsize factor of - 1.74Comfort factor - 32Endeavour 32 year?Capsize factor of -1.76Comfort factor - 30.25Islander 32 year?Capsize factor of - 2.03 Not acceptableIslander Iona 32 year?Capsize factor of -1.9Comfort factor - 23.17Alberg 30 1968Capsize factor of -1.71Comfort factor - 30.97O’Day 32 1977Capsize factor of -1.91Comfort factor - 25.38Pearson 323 1983Capsize factor of -1.74Comfort factor - 30.88Kettenburg K32 1978Capsize factor of -1.86Comfort factor - 27.76  

Trevor - SailboatOwners.com

Another fun Sail Calculator Another fun Sail Calculator with an extensive database of boat models can be found at the Related link below. The program outputs a number of different categories in a bar chart format in a separate window. But remember, these are just numbers!Have fun,Trevor  

Be Careful With The Numbers Looking at these numbers are all well and good but they are derived from simple formulas and don't take into account many factors. And, additionally, how you setup your boat will change the numbers.For example:Capsize Ratio = Beam / (Displacement / 64)**0.333 Notice the only factors involved are Beam and Displacement. This means that, for the same displacement, a boat with a light-weight construction and a deep fin keel will have the same number as boat with heavy construction and a shoal-draft keel.To test what a few hundred pounds difference makes in displacement just run it through the formula and you will see that it makes a difference. If that little change in displacement makes that much difference just imagine what a difference taking into account the center of gravity and the lever arm would make. Think about that 8 or 9.9 hp outboard hanging on the stern rail, life raft and dingy on the coach roof, jerry cans of gas and water lashed to the life lines, etc.. Your numbers just changed big time.The formulas are "no brainers" but one needs to use a lot of judgment when using them.They make a good starting point for discussion, though, if you know what is behind them but don't treat them as gospel.  

Rough Numbers As John indicated, the MCR & CR don't consider all the numbers & variables, and should only be used for a very rough preliminary consideration of very similar boats.For instance (I'm paraphrasing Jeff_H from another forum):An extreme example: You could move a significant weight from a boat's deep keel to it's masthead, without affecting the formulaic outcome (very different boat realities, but same resulting ratios).Regards,Gord  

Richard A. Marble

Is there a better formula out there? I couldn't agree more. I wonder if there is a formula that takes the draft and keel weight into consideration. If there isn't why does'nt someone come up with one? It would be much better I would think.  

Isn't the CR really a righting ratio Richard, I am going to go off and confirm this info, but wasn't the capsize ratio developed by Ted Brewer to be an indication of a boats ability to recover from a capsize (the 180 position) and not specifically to be an indication of its initial stability? The factor favours less beamy boats which have less initial stability when upright, but when turned turtle the lack of beam means they can be uprighted more easily. And of course the greater and deeper the ballast the easier the righting process.I seem to recall Ted pointing out that today's modern beamy boats may not be able to right themseleves when inverted due to their wide beam.Kevin  

Laura Bertran

I've seen different numbers... ...right on this site. The capsize factor for a Hunter 31 is 2.13.  

The capsize screening formula is useful because wide light boats don't roll back up as quickly as narrow heavy boats. There are other numbers that can be calculated to give the range of positive stablity. It is odd that boat manufacturers almost never include this data. But for the few boats that I've compared if the CSF is low the boat is generally considered seaworthy. But even the range of positive stability may not be a better indication in that capsizing is a dynamic event and the RPS is a static measure. The CSF came about by looking at boats that survived the Fastnet?? disaster as opposed to those that didn't. It is an empirical observation rather than a theoretical calculation.  BTW I have a book that has a photo of a beamy fin keeler in the turtle position with the crew standing on the hull. Yes the keel is still attached!! Once that mast is underwater with sails it would take a lot to bring it back upright.  

newly anonymous

does not compute That capsize screening formula is almost universally criticised for being overly simplistic. It does not take into consideration the all-important ballast/displacement ratio, nor does it factor ballast/draft. If my boat displaces 20,000 pounds, it makes a tremendous difference whether 6,000 of those pounds are in ballast or 8,000 are. My H410, which displaces 20,000 pounds, has a bulb keel of 7,500. Surely this bulb keel gives it superior capsize stability than a fin keel would, but the formula doesn't take that into consideration. Neither does it factor whether I have the deep keel version or shoal draft. To simply factor beam verses displacement is ludicrous.  

Please give me an example of a cruising boat generally recognised as a seaworthy blue water cruiser that has a CSF greater than 2!!!!Check out allied seawind,Pacific seacraft,swans,cape dorys, etc etc I haven't done an extensive survey but every one that I have looked at had a CSF of 1.8 or less.  

Jeff M21319

IMHO, the calculation is so simplified... that it is useless. From an engineering viewpoint, so many relevant variables have been left out that any conclusions drawn using the formula presented are essentially false. While beam and displacement are important numbers, they certainly aren't the only ones that need to be considered and given a place in such a complex analysis. Kind of reminds me of the old 'skid charts' the police would use to determine the speed of a vehicle immediately prior to a colision. They would take the length of a skid mark, determine the type of road surface and then look it up on a little chart to get the estimated speed. No accounting for such things as vehicle weight, tread width, condition of tread, inflation pressure, etc. was done.  While I'm certainly not a naval architect, it would seem that determining a boats inherent ability to self-right after going inverted would require complex computer modeling, tank testing and perhaps other sophisticated methodology to get anywhere near a correct answer. Even then, one would have to look at variables such as type and size of sails aloft during the event, actions taken by the crew immediately prior to and after the event and a myriad of others. Sorry, but I just can't buy into a calculation so inherently flawed. P.S. Has anyone ever heard of or contemplated something along the lines of an auto-inflating PFD that would be mounted at the top of the mast and deploy after being submerged? I wonder what (if any) effect this would have, given a few hundred pounds of positive bouancy, on initiating a self-righting action? Perhaps I'm crazy (although it's never been proven in court!) but would something along the lines of a 4' diameter inflatable mooring ball tied to the top (bottom) of an inverted mast do much to get a 10 ton boat headed back onto her feet? What if it also had, via some mechanical means, the ability to 'blow' the main and jib halyards to remove the resistance of the sails to the righting movement? Just wondering.  

Just asked Bob Perry on cruising world's BB He didn't put much value on the CSF in and of itself. He said that bigger is better in that a longer boat is less likely to capsize. He also said that for cruisers that if you stay away from radical designs and have a moderate beam and displacement/length or 220 or better you'll probably be alright. But if you think about it a heavier boat D/L>220 and a moderate beam will probably give you a CSF of less than 2.0.Bob Perry please forgive me if I misquoted. My only attraction to the CSF is that it is a readily available number to compare boats. If you look at SA/Displ,Disp/wll, motion comfort ratio beam/length,PHRF etc you get an idea of what the boat is like. Of course all of these numbers are indications of how the boat probably will perform. Ideally you would have the time and money to hire an expert designer to evaluate the boat. But for some boats this would cost more than the boat!!!!!!  

So the verdict is According to what I’m reading, This capsize formula is pretty much worthless to really determine if your boat will capsize or if it will right itself. That said, generally speaking a boat with a higher number is probably less capable of staying upright than one that has a lower number. So when someone is looking at boats, I guess, use this formula but keep in mind that the lower the keel and the heavier the keel the better. Also you should keep in mind mast height and how much freeboard there is above the water line.Now why doesn’t someone come up with a better formula? While it may not be perfect I’m sure it could be better than this one.  

henkmeuzelaar

Uncomfortable truths about "comfort factors"..... What is the point of even discussing the value of such dimensionless empirical numbers when one is unlikely to find two sailors who completely agree on what "comfort" (or rather: "comfortable motion") at sea really is? Just try to start a rational discussion on this topic between avowed mono- and multi-hullers and you will soon see the futility of such an exercise.Perhaps we should all remember one other fact as well: there is currently no model (i.e. quantifiable level of understanding) that even begins to describe the dynamic behavior of a sailing vessel at sea. If that sounds like a bit of an exaggeration, just consider the fact that current models for boat speed at different points of sail and wind strengths are only valid for flat water! In other words, no one is even able to fully describe what the effects of seastate on something as straightforward as BOAT SPEED are...... IMHO, anyone who accepts the claim that some magical formula can predict the effect of seastate on something as complex as "comfortable motion in a seastate", while at the same time acknowledging that our current level of understanding is insufficient to predict something as comparatively simple as the effect of seastate on boat speed, would appear to have some issues to deal with that fall well outside the scope of this board.Have fun!Flying Dutchman  

You're Right Richard - Take With A Grain of Salt By jove I think you've got it! These formulas make a good starting point for discussion purposes.If nothing else, if your post got you thinking about what's going on that's good. You've started asking questions - that's good. Not taking everything hook-line-and sinker, that's good.I'm thinking about my own boat which is much the same as the Hunter 35.5 and has an aluminum toe rail. The Toe rail is bolted onto a flange on the hull and deck and sticks out about 2 or 3 inches. The beam is the width to the outside of the toe rail. So, do you plug in the manufacturers published number for the beam or use the beam measured to the outside of the hull? At 2" x 2 that's 1/3 of a foot, 0.333. At 3" x 2 that's 0.500 feet. Hey! That's significant!Then there are the other things that don't even fit "The Formula", like how one loads the boat, things one can do to rectify a bad situation (creative flotation devices were mentioned). So the point is there are a lot of variables that aren't in the formula. I guess if a point can be made that this MAY true with all the other formulas too so take the formulas with a grain of salt. The PHRF formula isn't exact either and it incudes many more variables but for speed on a race course, as a rule, it gets pretty darn close. There are exceptions, though, such as the handicap factor for a fixed-blade prop.Not only should one think about and question the forumulas, one should always be thinking when you're on the boat. Things happen and you have to be creative with ways to work your way out of a bad situation. Whether it's a squashed pinkiy up the inside passage (this happened to the Pardey's), getting a boat up-righted, or just getting between those two boats coming toward you in a narrow channel. We are really on our own out there, some times more than others, and you can't necessarily just call 911 to be taken care of.Bottom line - use the info with a grain of salt and think for yourself. And .... if your boat isn't reasonably water tight the best number in the world won't mean a thing.Now go out there and have fun.  

Henk Is your boat an FD=12?Dennis  

Nah, HL43. Tell us about your Windship, though! Flying Dutchman is just the nickname my crew gave me (probably because I am such a nice guy ;D). For the past decade, or so, I have been using this handle faithfully in order not to give anyone a chance to change it into Captain Bligh......The name of our Hunter Legend 43 (hull #1) is Rivendel II. Just type "Rivendel" under Search as far back as Phil's archives go these days and you will get a pretty good idea about what she's been up to.Have fun!Flying Dutchman  

Fred Ficarra

CSF I still believe in formulas that are used with caution. Take my chick screening formula as an example.weight X height in inches/ageX150. Usually women with a CSF of 2.2-1.8 are acceptable. If the number gets too high she is too fat or young. If the number gets too low she is too old ,short or skinny. If I throw in a couple of qualifying limits the results are better. Say older thatn 18 and younger than 35. But then you might get a perfect number and the girl be unacceptable for other reasons such as she doesn't like old farts!!!!Example a 62" woman weighing 120#s and 25 years old = 1.98 if she is 55 that number changes to =0.90 which is clearly an unacceptable number. Maybe I should factor in red hair and a large bank account???? But heck it's hard enough to get a woman to devulge her weight and age!!!!!!! Maybe a beer factor where .25 is added or subtracted for each beer consumed in the last hour????  

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Sailboat Specifications 101: Explained For Beginners

As a newbie to sailing, the sailboat specifics can be overwhelming. Taking time to familiarize yourself with the measurements and vocabulary associated with boats will allow you to be more informed about boats and know which type is right for which activity. You’ll be a better sailor and boater with this knowledge.

Table of Contents

LOA – Length Overall

Length Overall (LOA) is the most common measurement used to describe the size of a sailboat. It refers to the total length of the vessel, from the tip of the bow (front) to the aft end of the stern (back).

LOA is typically measured in feet or meters. This measurement can be useful when comparing boats of similar types, as it gives you an idea of the overall size.

LOD-length on deck

LOD, or Length on Deck, is the measurement of the boat from the tip of the bow to the stern along the deck.

This length does not include any spars, bowsprits, antennas, etc. that are mounted above the main deck.

The difference between LOD and LOA (length overall) is that LOA takes into account any protrusions such as spars and bowsprits. LOD may be shorter than LOA sometimes.

LWL – Load Waterline Length

The LWL or Load Waterline Length is the measurement of the length of a boat at the point where it touches the water.

It is the length of the boat that makes contact with the water and is often shorter than the overall length (LOA) due to the curvature of the hull.

The LWL plays an important role in determining the performance of a sailboat; for example, a longer LWL can help increase stability and reduce drag, allowing the boat to move more efficiently through the water.

The LWL also affects the size of the sail area needed to power the boat. As such, boats with a longer LWL will require larger sails to generate adequate power, while boats with a shorter LWL may need smaller sails.

Beam – The width of the boat

The beam of a sailboat is the maximum width of the hull and is an important measurement for sailing performance.

A wider beam provides more stability on the water and increases the overall sail area. Having a larger sail area will help to increase speed and maneuverability in windy conditions.

It’s important to consider the beam of the boat when deciding what type of sails to use. A boat with a wider beam will require bigger sails, while a boat with a narrower beam will require smaller sails.

Draft – The depth of the boat in the water

Draft measures the distance from the waterline to the lowest point of the boat’s hull when it is fully loaded.

This is important because it affects the boat’s maneuverability, stability, and performance in different sea conditions.

It also affects the sail area of the boat, since a greater draft can provide more stability and lift, allowing for larger sails to be used. Shallow draft boats tend to be able to get into shallower waters than those with deeper drafts.

Full keel vs. modified keel vs. fin keel

The three main types of keels are full, modified, and fin keels.

Full keels are the oldest and most traditional type of keel. They are typically found on heavier displacement boats such as cruisers and larger sailboats.

Full keels provide more stability due to their size and weight, but also create more drag, which can slow down the boat.

Modified keels are a hybrid between full and fin keels. They are often used on boats with moderate displacement, meaning they have a moderate amount of weight.

Modified keels provide a good balance of stability and speed due to their shape and size.

Finally, fin keels are usually found on lighter displacement boats such as racing and performance sailboats.

Fin keels have the least amount of drag, allowing the boat to move faster, but they are not as stable as full or modified keels.

Displacement – The weight of the boat

The displacement of a boat refers to the total weight of the boat, including all of the materials used to construct it. It is usually measured in either metric tonnes or long tons.

The type of displacement your boat has will depend on its size and purpose, with light displacement boats usually being used for day sailing and racing, while moderate and heavy displacement boats are better suited for coastal and ocean cruising.

Light displacement boats are typically quite lightweight, with a hull weight of around 2 tonnes and a total weight of 4 tonnes or less.

These boats are often very fast and agile but can have limited load-carrying capacity due to their light construction.

Moderate displacement boats typically weigh between 4 and 10 tonnes, with a hull weight ranging from 3 to 8 tonnes.

These boats are best suited for coastal cruising and are usually made from heavier materials than light displacement boats. This makes them able to carry a greater load and handle rougher seas with more confidence.

Heavy displacement boats weigh more than 10 tonnes, with a hull weight of up to 15 tonnes.

These boats are built for long-distance ocean cruising and are designed to be sturdy and reliable even in heavy weather. As such, they are usually made from stronger materials than other types of boats and have a much larger load-carrying capacity.

D/L or DLR ratio- Displacement to length ratio

Displacement to length ratio (DLR) is a calculation used to measure the size of a sailboat.

It is determined by dividing the displacement (the weight of the boat) by the waterline length (the length of the boat that is in contact with the water when it is afloat).

The result of this calculation, also known as the DLR, can be used to compare different types of boats or to determine which type of sailboat is most suitable for specific conditions.

The formula for calculating the displacement-to-length ratio is: DLR = (Displacement/2240)/(0.01xLWL)^3 Displacement in pounds, LWL is Waterline Length in feet

Generally, sailboats with higher DLRs tend to have a more rounded hull shape and are better suited to deep-water sailing in heavy weather conditions.

Sailboats with lower DLRs tend to have a more slender hull shape and are better suited to shallow water sailing in light weather conditions.

Ballast is the weight of the boat that is not part of the boat’s structure. This weight can come from a lead, water, or other materials, and it is located in the bottom of the boat to help keep it stable in the water.

The amount of ballast affects the sail area, as more ballast will lower the sail area while decreasing ballast will increase the sail area.

This is because when there is more ballast in the boat, it will be pushed down into the water which reduces the area that a sail can reach. On the other hand, decreasing ballast will allow a sail to extend further.

Ballast is also important for maneuverability and stability; too much ballast and the boat will be sluggish and difficult to turn, while too little ballast could cause the boat to be unstable and even capsize.

Balancing the amount of ballast is key to achieving optimal performance for any type of sailboat.

CSF-Capsize screening formula

The capsize screening formula is a calculation that provides a good indication of the stability of a sailboat. It is the ratio of a boat’s displacement (weight) to its Beam (width).

Capsize ratio formula: Beam / ((Displacement/64.2)1/3) The beam is in feet. Displacement is in pounds

A good capsize ratio is generally considered to be between 1.33 and 2.0, although this can vary depending on the type of boat and its purpose.

A lower capsize ratio indicates that the boat is more stable, as it will be less likely to tip over in strong winds or waves. A higher capsize ratio indicates that the boat is more prone to capsizing.

Motion comfort ratio

Motion comfort ratio (also referred to as “Ted Brewer” ratio) is a measure of the overall stability of a sailboat.

Generally, a boat with a motion comfort ratio greater than 40 is considered stable and a boat with a motion comfort ratio less than 30 is considered unstable.

A boat with a motion comfort ratio between 30-40 is considered moderately stable. The higher the motion comfort ratio, the more comfortable the boat will be in rough waters.

Ted Brewer’s CR formula is: Displacement in pounds/ (.65 x (.7 LWL + .3 LOA) x Beam 1.333 ).

For instance, a boat with an LWL of 35 ft and a displacement of 10,000 lbs would have a motion comfort ratio of 37.5. This would indicate that the boat is moderately stable and should provide an adequate level of comfort in rough waters.

The motion comfort ratio was developed by Ted Brewer and has been used for many years as an indication of a boat’s stability.

It is important to keep in mind, however, that this ratio alone cannot give an accurate picture of how stable a boat is. Other factors such as hull type and keel type should also be taken into account when assessing a boat’s stability.

Ballast to displacement ratio

The ballast-to-displacement ratio is a measure of how much ballast is needed in relation to the weight of the boat.

The higher the ballast-to-displacement ratio, the more stable the boat will be and the less likely it will be to capsize.

the ballast-to-displacement ratio is important for ensuring the boat is adequately balanced and has good performance when sailing.

It is especially important for boats that have large sail areas, as larger sail areas require more ballast to keep the boat steady.

When considering a boat’s ballast-to-displacement ratio, keep in mind that a ratio of 40-50% is generally considered to be optimal. Any higher than that may be too much, while any lower may not be enough.

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Numbers geek specifically capsize formulas

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As I go about searching for my "ideal" boat I look at their various performance numbers and the one I gravitate to most is the capsize screening formula. The boats I am most drawn to such as a Tayana 37 and a Nicholson 32 have a 1.63, and a 1.61, respectively. I was reading a book about offshore boats and one of the recommended boats was an Oceanis 430 which has a 2.05 capsize number. Do these numbers really matter? Is the boat with a number slightly over 2 really going to go belly up faster than one well below 2?  

Quit looking at numbers. I’ve never heard of a 430 rolling over, but I’ve heard of a few that lost the rudder/ post and were abandoned and/ or sank. don’t know the capsize ratio of the Catalina 30, but you’re more likely to lose the mast or rudder first, which would then are more of a concern- and would change the capsize ratio. what’s the capsize ratio of the R Class boats? Probably not scary, they have tons of lead and a narrow hull. But if you’re in waves that will capsize an R Class, the fact that it’s a U boat, barely above the water, is the concern. Best bet is to read here and see what real life experienced sailors say.  

Ratios and numerical specs are one way to look at boats, but they will never tell you the whole picture. Put another way, a boat is more than the sum of its specs. I wouldn’t get too fixated with any of these specs. And that’s coming from someone who owns a boat with a 1.6 capsize ratio.  

The numbers cannot be used to determine anything about an offshore boat, because they do not take into account that they are controlled by humans, and the sea state and wind will create conditions no formula can factor in. Much more important, IMO, is the live-ability and comfort of your new home on the water, at sea, on the pick or on a mooring. For instance; if you are headed to the tropics will the boat have better than adequate ventilation, storage for tools, spare parts, sails, and your personal gear? That stuff is far more important when I go looking for a live aboard cruising boat. How close a boat can point to the wind should hardly be of importance to a cruiser, who should be much more interested in how comfortable she is for the crew. Racers are a different story, of course. I would also strongly suggest that you do not become emotionally involved with a boat before you own it, especially if you are going cruising. If you let your eyes choose your boat for you, it is more likely than not that you will find yourself regretting it in a rolly anchorage or other conditions which make being aboard unpleasant. I don't think anyone who has spent some time in Prickly Bay, Grenada would disagree. Always remember, you are searching for your home on the water, where you might live for an extended period. So, think comfort first and foremost, after you have a well found boat in sight.  

While many of the calculated numbers do matter (SA/D. D/L, DWL/LOA, BAL ratio, LBS/IMERS.Inch, etc.), within the yacht science and yacht design community, the Capsize screen Formula and Motion Comfort Index formulas have largely been deemed to provide no useful information. This is the case because these surrogate formulas do not include most of the critical factors that actually impact motion comfort or the likelihood of capsize (such as damping, horizontal and vertical buoyancy and weight distribution, waterline plane, the extent to which the beam of the boat is carried fore and aft, and roll and pitch moments of inertia and so on) and in the case of the impact of beam, both have beam as a negative while the current science suggests that beam is helpful in resisting capsize and that waterline beam rather than the beam measured at the deck is more critical for motion comfort. The net result is that these formulas tell almost nothing about the reality of a boat's likelihood of capsize or its motion comfort. In fact they provide so little indication of a boat's behavior that to rely on them in any way borders on the dangerous. To further explain, both of these formulas were developed at a time when boats were a lot more similar to each other than they are today. The formulas were intended to provide quick and easy to calculate rules of thumbs based on the hull forms, weight distributions and rig proportions of the day. The half century old Motion Comfort Index and the 40 plus year old Capsize Index preceded the many decades of research and the resultant scientific understanding that has occurred since they were penned. As a result, at best, these formulas have limited utility in comparing boats other than those which are very similar in weight and buoyancy distribution to each other. The reason that it is useless to apply these formulas to compare boats with differing hull forms is that both formulas over emphasize displacement, which turns out to play a minor role in either motion or capsize likelihood. And both treat beam overly simply, and in the case of the capsize screening formula has beam as a negative rather than a positive it is now understood to be. Neither formula contains almost any of the real factors that control motion comfort, the likelihood of capsize, or seaworthiness. Neither formula contains such factors as the vertical center of gravity or buoyancy, neither contains weight or buoyancy distribution (of the hull both below and above the waterline), the extent to which the beam of the boat is carried fore and aft, and neither contains any data on dampening, all of which really are the major factors that control motion comfort or the likelihood of capsize. The disconnect between these formulas and real life in large part results from the way that they were derived. The data used to create these formulas were based on the hull forms that existed at the time, which mainly were traditional heavy displacement for their length cruisers, CCA era race rule beaters, and IOR race rule beaters. The inventors of the formulas tried to boil down the easily measured characteristics of these three hull forms, noting that the traditional heavy displacement for their length cruisers had the smallest chance of capsize and the most comfortable motions, and IOR boats the worst behavior with CCA era boats somewhere in between. They interpolated the results of a few easily measure factors and that became the formulas. In the days before computer simulations and real life documentation, that approach made sense as a stop gap. It no longer does. I typically give this example to explain just how useless and dangerously misleading these formulas can be. If we had two boats that were virtually identical except that one had a 500 pound weight at the top of the mast. (Yes, I know that no one would install a 500 lb. weight at the top of the mast.) The boat with the weight up its mast would appear to be less prone to capsize under the capsize screen formula, and would appear to be more comfortable under the Motion Comfort ratio. Nothing would be further than the truth. The added weight would of course reduce positive stability and would therefore make a capsize more likely. Similarly, the weight at the top of the mast would cause the boat to roll and pitch through greater roll and pitch angles, and the added inertia would cause the boat to get out of sync with the wave train and so have greater impacts with each wave. And while masthead 500 lb. weight example would clearly appear to be so extreme as to be worthy of dismissal, in reality, it may not be that for off. For example, if you compared two boats. The first has a very heavy interior, shoal draft, its beam carried towards the ends of the boat near the deck line, a heavy deck and cabin structure, perhaps with traditional teak decks and bulwarks, a heavy rig, heavy deck hardware, a hard bottomed dingy stored on its cabin top or in a davit, and the resultant comparatively small ballast ratio made up of lower density ballast. And if we compare that to a boat that is lighter overall, but it has a deep draft keel, with a higher ballast ratio, the bulk of the ballast carried in a bulb, its maximum beam carried to a single point in the deck so that there was less deck area near the maximum beam, a narrower waterline beam, a lighter weight hull, deck and interior as well as a lighter, but taller rig, it would be easy to see that the second boat would potentially have less of a likelihood of being capsized, and it is likely that the second boat would roll and pitch through a smaller angle, and would probably have better dampening and so roll and pitch at a similar rate to the heavier boat. In other words the lighter boat would offer a better motion comfort....And yet, under the Capsize Screen Formula and the Motion Comfort Index it would appear that the first boat would be less prone to capsize and have a better motion when obviously this would not be the case. There are some better indicators of a vessel’s likelihood of capsize. The EU developed their own stability index called STIX, a series of formulas which considered a wide range of factors and provides a reasonable sense of how a boat might perform in extreme conditions. Unfortunately meaningful results require a lot more information than most folks have access to for any specific design. (you may be able to find the STIX values for some modern European boats). The Offshore Committee of US Sailing developed the following simplified formula for estimating the Angle of Vanishing Stability (Sometimes referred to as the ‘AVS’, ‘limit of positive stability’, ‘LPS’, or ‘Latent Stability Angle’ ): Screening Stability Value ( SSV ) = ( Beam 2 ) / ( BR * HD * DV 1/3 ) Where; BR: Ballast Ratio ( Keel Weight / Total Weight ) HD: Hull Draft DV: The Displacement Volume in cubic meters. DV is entered as pounds of displacement on the webpage and converted to cubic meters by the formula: Displacement Volume in Cubic Meters = ( Weight in Pounds / 64 )*0.0283168 The Beam and Hull Draft in this formula are in meters. The Angle of Vanishing Stability approximately equals 110 + ( 400 / (SSV-10) ) It should be noted that this formula only provides a very loose approximation and the AVS is only one indicator in evaluating the likelihood of capsize, meaning it only predicts the point at which the vessel wants to turn turtle. It does not predict the amount of force that would be required to heel the vessel to that limit, nor does it predict how the shape of the boat might encourage wave action to roll the boat closer to the angle at which it no longer wants to return. It also does not include the impact of the freeboard of the boat, the change in pitch and buoyancy distribution due to heel or pitch, the positive and negative buoyancy due to the cabin structure or the cockpit. Those characteristics require a much more nuanced calculation based on the specific design boat in question, but that more detailed analysis is what it takes to produce truly accurate and meaningful results. Jeff  

If you asked 10 sailors in a bar what the capsize ratio was for their boat, at least 9, myself included, would shrug.  

Not the guy with the Sunfish. His capsize ratio is about 95%, especially if he's 15, with three friends, and it's 95F.  

And if he's in the bar at 15, he's well accustomed to tipping over on land or on the water...  

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Capsize – how it happens

Posted by John Vigor | Sailing Tips

Planning for an unplanned inversion

Capsize: how it happens, and what you can do to survive it.

When Isabelle Autissier’s 60-foot racer capsized in the Southern Ocean, it sent a chill of fear through the sailing community. Sailors don’t like to think of capsize. But here was a big, well-found boat, a Finot-designed Open 60 Class flier, wallowing upside down in huge frigid swells, with her long thin keel jutting toward heaven. It was a bizarre and frightening sight.

Autissier was lucky. She was taking part in the Around Alone race, so her million-dollar boat was equipped with emergency satellite transmitters, position recorders, and lots of other equipment that no normal cruiser is likely to be able to afford or fit on board. She was eventually rescued in a wonderful feat of seamanship by Giovanni Soldini, a fellow competitor.

So what went wrong? And could it happen to you? It depends where you sail, but if you sail out of sight of land, whether at sea or on a lake, the answer is yes, it could. And you should always be prepared for it to happen. The good news is that most yachts of classic proportions will survive a capsize. Unlike Autissier’s extreme design, they will right themselves, although some might take longer than others.

You can form a crude idea of what went wrong with Autissier’s boat by imagining a long plank floating in the water. It doesn’t care which side is up. It’s happy floating either way up. That’s Autissier’s boat. Now imagine a plank with a heavy weight attached along one side, so the plank floats on edge. If you turn it upside down, the ballast quickly pulls it back again. That’s your normal yacht design. Autissier’s racer was shaped too much like a wide plank – too beamy and too light to recover from an inverted position, despite the long heavy keel. It’s one of the paradoxes of naval architecture that an excessively beamy boat, while hard to capsize in the first place, is unseaworthy if she is inverted.

Furthermore, a light, shallow, beamy boat capsizes more easily than a narrow, deep, heavy boat because she offers the seas more leverage to do their work, and because she is quicker to respond to the upward surge of a large swell.

Planing hulls

Designers create racing boats like Autissier’s because that shape gives them the ability to plane at high speeds. In other words, they deliberately sacrifice seaworthiness on the altar of speed, and the boats rely on the skill of their crews to keep them upright. Unfortunately, singlehanders have to sleep now and then, so they can’t be on watch all the time.

While it’s true that a good big boat is less likely to capsize than a good small boat, there is no guarantee that even the largest yachts are immune from capsize. It’s not the wind that’s the problem. It’s the waves.

Tests carried out at Southampton University in England have shown that almost any boat can be turned turtle by a breaking wave with a height equal to 55 percent of the boat’s overall length. Even if you don’t like to think about it, you know in your heart that it’s a reasonable finding. It means your 35-footer could be capsized through 180 degrees by a 20-foot wave. Even a 12-foot breaking wave would roll her 130 degrees from upright – from which position she may turn turtle anyhow.

And if you imagine you’re never going to encounter a 20-foot wave, think again. Waves of that size can be generated in open water by a 40-knot wind blowing for 40 hours. And a 12-foot wave is the result of a 24-knot wind blowing for 24 hours. Plenty of those around.

Large waves are formed in other ways, too. A current flowing against the wind will create seas that are much larger and steeper than normal. And the old stories about every seventh wave being bigger than the rest have a basis of truth, although it’s not necessarily the seventh wave. It could be the fifth or the ninth. The point is that wave trains occasionally fall in step with each other at random intervals, literally riding on one another’s backs, to form an exceptionally high wave. We call that a freak wave, but it’s actually more normal than we care to admit.

Bigger waves

Scientists calculate that one wave in every 23 is more than twice as high as the average. One in 1,175 is three times bigger. And one in 300,000 is four times the average height. They may be far apart, but they’re out there, and many big ships have been lost to them.

John Lacey, a British naval architect, put forward an interesting proposition after the 1979 Fastnet Race, in which 63 yachts experienced at least one knock-down that went farther than 90 degrees and remained upside down for significant periods.

He explained that the old International Offshore Rule for racers had radically changed the shape of yacht hulls by greatly increasing the proportion of beam to length, which gave them more power to carry sail without the need for additional ballast. It also gave them more room below, of course.

But the flatiron shape of the hull made it very stable when it was inverted. To bring the boat upright again would require about half the energy needed to capsize the yacht in the first place, Lacey calculated.

“Since the initial capsize may have been caused by a once-in-a-lifetime freak wave, one could be waiting a long time for a wave big enough to overcome this inverted stability,” he commented. Autissier’s experience bore out that prophetic statement. Her boat was still upside down when she abandoned it.

Lacey did some more sums and figured that a narrower cruising hull with a lower center of gravity than a typical IOR boat would require only one-tenth of the capsize energy to recover from a 180-degree capsize.

“It therefore seems, in my opinion, that we should tackle the problem from the other end, and design yachts for minimum stability when upside down,” he concluded.

Deep-vee cabin

His recommendation is not likely to be taken too seriously, but he certainly does have a point. You could make an inverted yacht unstable with narrow beam, a very deep keel with a lot of weight at the very end of it for righting leverage, and a deep-vee cabintop, or at least one that was narrow on top and broad at deck level. For the same reason, flush-decked yachts should be avoided, because they’re likely to be much more stable upside down.

But as in everything to do with sailboats, there are compromises to be made. Deep narrow hulls might recover quickly from inversion, but as sailors discovered a century ago when they were all the rage, they’re lacking in buoyancy. They’re also wet, and they have very little accommodation.

Two basic design features probably govern the probability of capsize more than any others. The first is inertia and the second is the shape of the keel.

Inertia is not generally well understood, but it’s the first line of defense against a wave impact. In simple terms, inertia is resistance to change. The inertia of a moving boat works to keep her moving on course, even though other forces are trying to halt or divert her. The inertia of a boat at rest resists any sudden attempt to start her moving.

Obviously, because inertia varies with mass, a heavy boat has more inertia than a light boat, so a wave hitting her from the side is going to get a slower response. Light-displacement boats are more likely than heavy boats to be picked up and hurled over by a plunging breaker.

Narrow beam is a help, too, because the force of a breaking wave is concentrated nearer the centerline of the yacht, where it has less overturning leverage.

Spreading weight

The way weight is distributed on a boat also affects its inertia. A wide boat with a light mast and a shallow keel will respond very quickly to every wave with a lively, jerky motion. A boat with a heavier mast and a deeper keel has its weight spread out over a greater span, and it’s more difficult to change its speed or direction, so the force of a breaking wave may be dissipated before it has a chance to overturn the boat. Inertia, incidentally, is what keeps a tightrope walker aloft. It’s contained in that long stick. If you push down on one side of it suddenly to regain your balance, it almost bounces back at you. It will subsequently move slowly away, but you can recover it with a long gentle pull as you lean the other way.

A long, old-fashioned keel resists sudden rolling simply because it’s difficult to move anything that big sideways through the water. A fin keel, with its meager surface area, is much more easily moved when it’s stalled; thus, the boat to which it’s attached is more easily overturned. But a fin keel that’s moving through the water acquires much more stability, which is why fin keelers should be kept moving in heavy weather.

Capsize screening formula

The maximum beam divided by the cube root of the displacement in cubic feet, or Maximum beam (feet) = less than 2 3÷Displ/64 The displacement in cubic feet can be found by dividing the displacement in pounds by 64. The boat is suitable for offshore passages if the result of the calculation is 2.0 or less, but the lower the better.

Although there are design factors that improve seaworthiness (usually at the expense of speed and accommodation), and although there are tactics you can use in a storm to minimize the chances of overturning, no boat is totally capsize-proof. That is not to say that every boat is going to capsize, of course, even the ones most likely to. After all, hundreds of yachts cross oceans every year without mishap. But prudent sailors keep the possibility in mind and do what they can to forestall any problems and to lessen any damage resulting from an inversion.

Large forces

If you have never given any thought to inversion, the results of a capsize can be devastating, not only on deck but down below as well. Not many people realize what large forces are involved in a capsize, especially the head-over-heels capsize called a pitchpole. It’s not just a gentle rolling motion. The contents of lockers and drawers can be flung long distances in the saloon, and you could easily find yourself standing in a state of disorientation on the overhead in a seething mess of battery acid, salt water, clothing, ketchup, mayonnaise, diesel fuel, paint thinner, knives, forks, and shards of broken glass. There will be no fresh air entering the cabin to dissipate the fumes. And it will be dark because your ports will be under water.

So, first things first: presuming you haven’t been injured by flying objects, can you lay hands on flashlights? Were they stored safely in a special place that you can reach without having to shift a wodge of soaked bunk mattresses? Is there one for every member of the crew? Are the batteries fresh? You may not stay upside down for long. But if you’re unlucky, like Isabelle Autissier, you will find you need a flashlight more than anything else on earth.

There are some other things you should think about before you ever set sail. And there are some precautions you can take.

Avoiding capsize

• Avoid heavy weather. “The most dangerous thing on a boat is an inflexible schedule.” Thanks to Tony Ouwehand for this observation.
• Avoid taking large waves abeam, particularly breaking waves.

Heave to. Run (down wave) using a drogue to keep speed down to 3 to 5 knots. Use a sea anchor from the bow or a series drogue from the stern. (Practice rigging and deploying these in moderate conditions.)

• Is your rig as strong as possible? Will it withstand the tremendous forces of a capsize?
• Do you have a plan to free a toppled mast from alongside, where it can batter holes in your hull? Have you ever thought how difficult it would be to cut the rigging, even with a decent pair of bolt cutters, on a slippery deck that’s suddenly rolling viciously?
• Do you have material on board for a jury rig? Have you thought about how you would use it?
• Will your radio transmitter’s antenna come down with the rig? Do you have a spare?
• Will your EPIRB start working automatically because it’s been under water – whether you want it to or not?

The cockpit

• Are your cockpit lockers waterproof? Can you imagine how quickly you’d sink if one of them was open at the time of capsize?
• Do your companionway hatchboards lock in position? Have you ever thought how much water would get below if one or more fell out as you turned over?
• What have you done about waterproofing the cowl vents for the engine? Those are huge holes in what would become the bottom of the boat. (The same goes for Dorade boxes, incidentally. Each one is a potential three- or four-inch hole in the bottom. Fit them with deck plates for sea work, on deck and down below.)
• If you’re in the cockpit when the boat capsizes, will you be attached by a harness? Will you be able to free yourself if you’re trapped under water and the boat stays inverted for some time?

The anchor locker

• If the anchors and chain are not fastened down securely they could bash their way through the locker lid and cause all kinds of havoc.
• Is your self-draining deck anchor locker waterproof? Many aren’t completely sealed at the top, where wires for pulpit-mounted running lights come though, and would let in water.

The engine room

• Is your engine mounted securely enough to withstand a capsize? I know of one boat in which the engine was hurled from its mounts during a pitchpole, causing great destruction.
• What if the engine’s running during a capsize? Could you switch it off quickly, with everything upside down? Would the oil run out? Would the fuel drip out of the tanks? Are your breathers inside or outside?
• Are the batteries fastened down firmly enough? Can you imagine what damage they could do if they got loose? And will they drip acid if they’re upside down? (Newer batteries – gel cells and AGMs will not spill acid when inverted. -Ed.)
• Can you turn the stove off? If there’s a smell of gas, can you deal with it? Have you made sure the galley cupboards can’t fly open during a capsize and turn the saloon into a sea of broken glass and chip dip?
• Can you lay hands on a fire extinguisher quickly? It could save your life.
• Have you figured out a way to keep all those loose tops in place in the saloon – the boards that cover access to storage under bunks, the bilge boards, and so on? Some boats have inside ballast, and many have heavy objects, such as storm anchors, stowed in the bilges. Make sure they stay there, because if they get loose they can come crashing through the overhead (your new “floor”) and sink the boat very quickly.
• Make sure your bunk mattresses will stay in place, too, otherwise they will greatly hamper your attempts to get around.
• Have you figured out a way to pump bilge water out of an inverted boat? Think about it. It’s not easy.
• Most books could escape from their racks during a capsize and become potentially harmful flying objects. Have you solved that problem?

Important documents

• The ship’s papers and your own personal documents should be in a watertight container in a secure locker, one that is not too high up in the boat because that’s where the water will be when you capsize.

There are many other systems and pieces of gear on a boat that could be affected by a capsize. When you use them, think inverted. Imagine what would happen if they got loose. Invent ways to keep things in their places during an unplanned inversion. Don’t ever imagine it’s wasted work. It’s one of the unspoken rules of the sea that if you’re prepared, the worst is not likely to happen. If you’re not, you’re bound to attract trouble.

More on the subject

Tami Ashcraft wrote a compelling story of the realities of inversion and its aftermath in her book, Red Sky in Mourning: The True Story of a Woman’s Courage and Survival at Sea , reviewed in our May 2000 issue. John Vigor goes into more depth about preparation for capsize in his book, The Seaworthy Offshore Sailboat .

Article from Good Old Boat magazine, November/December 2000.

About The Author

John Vigor is a retired journalist and the author of 12 books about small boats, among them Things I Wish I’d Known Before I Started Sailing, which won the prestigious John Southam Award, and Small Boat to Freedom. A former editorial writer for the San Diego Union-Tribune, he’s also the former editor of Sea magazine and a former copy editor of Good Old Boat. A national sailing dinghy champion in South Africa’s International Mirror Class, he now lives in Bellingham, Washington. Find him at johnvigor.com.

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• December 16, 2016
• By Mariners Insurance

Safe Sailing: How to Choose A Safe Sailboat

There are certain non-negotiables every boat owner should have. These include a comprehensive Boat Insurance policy, an in-depth knowledge of nautical terms and boating procedures, and a safe boat. If your vessel of choice is a sailboat, skill and safety are especially important because sailboats require a higher degree of dexterity to operate and are more fastidious than motor boats.

Safety Features to Look for When You’re Sailboat Shopping

Sailboats are highly technical and assessing their safety level may seem like a daunting challenge if you’re not familiar with boat design. A great starting point for assessing safety are the following conclusions from the Cruising Club of America report on boat safety:

• Larger boats are generally safer than smaller boats.
• A sailboat without its mast is less safe than one carrying its full rig.
• Every boat has an “inherent stability range” that can be calculated based on the boat’s lines and specifications. Anything under 120 degrees is unsafe, because in the event of a capsize, those boats may remain inverted for up to 2 minutes – trapping occupants. When shopping for sailboats, ask the sales person what the boat’s stability range is. Or, contact USSailing , which has these measurements for many mass-produced boats.

Need to Know Number: Capsize Screening Formula

One of the biggest dangers of sailboat cruising is that the boat could capsize. According to Boats.Com , before you buy a boat, you should plug its numbers into the following formula:

Capsize Screening Rating = Boat’s Maximum Beam (feet)/Cube Root (Gross Displacement/64)

In other words, divide the boat’s gross displacement (in pounds) by 64, then determine the cube root of that quotient. Next, divide the cube root into the boat’s maximum beam (in feet). The answer you get is known as the boat’s Capsize Screening Number. If that number is two or less, the boat passes this important safety test. In general, anything over 2 is a failing score and indicates the boat’s stability is questionable. In rough sailing conditions, a boat with a failing capsize screening rating is at heightened risk of capsizing. If you’re serious about safety, you should probably move on and look for another boat.

About Mariners Insurance

Mariners Insurance was founded in 1959 to protect boat owners and marine business clients. We are marine insurance experts, and insure boats worldwide – in every ocean on the planet. Marine insurance is critical if you own a boat or nautical business. Trust the professionals – trust Mariners Insurance. Call us, 888-402-5018, any time you have questions or concerns about insurance for your vessel or marine business.

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• boat insurance , buying a sailboat , capsize screening number , safe boating , sailboat safety

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> > Please support our sponsors and let them know you heard about their products on Cruisers Forums. 14-03-2012, 15:37   Boat: Grew up sailing Blue Jays then Lightnings, Ensign 22, Hunter 33 sailed the PNW and loved it! Ratios? Are they really important and have any real meaning? I ask this question because after reviewing 27 foot sailboats, I have noticed they vary greatly. Example: the 27 varied from 1.79 to 2.1... The Norsea 27 seemed to have the best ratio of 1.59. I did not see a relationship between beam or type (perhaps I missed it). The 26M was 1.9 while the 26S was 2.24... A Tartan 27 is 1.77 where as my Dana 24 is 1.72. A Cheory Lee 26 is 2.14.. The website I obtained these numbers states under 2.0 is considered safe in rough conditions- then states the ratio is controversial LOL.. Just wondering how valid this ratio is and why it varies so greatly? Thanks 14-03-2012, 16:06   Boat: Under construction 35' ketch (and +3 smaller) formula for seaworthiness and such. BR Teddy 14-03-2012, 16:32   Boat: Grew up sailing Blue Jays then Lightnings, Ensign 22, Hunter 33 sailed the PNW and loved it! 14-03-2012, 16:51   Boat: Sundeer 64' ketch ratios look at Steve Dashew's 'Cruising Encyclopedia'. Go to setsail.com to see all and dvd's 15-03-2012, 19:26   Boat: Wauquiez Centurion 32 . You can find it for any you know these numbers for here To describe how useless it is if you take any and add 1000 lbs on , or high up the for instance, the number gets lower! A much more useful discussion of stability can be found here 15-03-2012, 22:10   Boat: Pearson 365 Sloop and 9' Fatty Knees. 15-03-2012, 22:26   blows hard, your boat will lean over away from the . if it's only the wind you will be ok because the wind at best will push you about 87 degrees away from it's direction. If your boat design is (and i only speak about mono hulls here) faulty you will drown, the boat will sink and someone on this forum will talk about how much worse it could/would have been if you were in a cat or tri.... If on the other hand you stuffed too much crap down below OR your boat has 'issues' with heeling then you will go swimming. cheers. bluetriguy. 15-03-2012, 22:28   for a couple of weeks. really, cheers 15-03-2012, 22:30   16-03-2012, 04:33   Boat: Mainship Pilot 34 boats">blue boats have about 140 degrees of stability: Pacific Seacrafts, Cabo Ricos, etc. Coastal cruising are in the 120 degree range. David 16-03-2012, 05:20   Boat: Gib sea 43 university tank model test, where they tested various cats up /down, various beams, various monos and they found all that was really important was lenght and beam, also could trip cats when abeam to the swell. having a boat with a good positive stability will not stop you being rolled by breaking waves , but you will spend a lot less time upside down in one and take on much less water. If the pen is mightier than the sword, then my keyboard must be a nuclear missile! 17-03-2012, 15:56   Boat: Cal 20 and weight together as a proxy for roll moment of inertia. Stevensuf's statement that 'bigger is always better' in regards to length and beam is incorrect. Consider a Westsail 32 vs a 37, the SC is longer and wider, but which is more likely to roll over in a storm? Or a WS32 and an SC40? Or a Triton 28 and a Kiwi 35? Mitiempo tries to use an absurdity to try to make his point. The formula is intended to be used on a normally ballasted in sailing condition. An extra 1000lb up the of most less than 45'-50' would roll them over at the , that's hardly sailing condition. This would be akin to saying a Toyota MR2 sportscar is bad car because it doesn't have the ground clearance to go off-roading. In reality it is a fine car for going fast on paved roads. Likewise if you use the formula in a manner outside what was intended you get bogus answers. By way of comparison, consider the alternative: remove the mast. The of that weight would increase the peak righting moment of the boat and increase the angle of vanishing stability. Physical testing has shown that boats without their masts are more likely to capsize in breaking waves contrary to the intuitive expectation. So then the question becomes what is the appropriate amount of weight aloft for capsize resistance? 1000lb is obviously absurd, but no weight aloft is not that good either. The answer is complex and involves tradeoffs between capsize resistance and ability to carry sail. I have read that in centuries gone by hoisting small to moderate weights into the was a way to prevent capsize and calm the motions of boats. I do not where I read this, I do not know if this is apocryphal. The only mention I can find currently is in Richard Henderson's book on handing where he indicates on pg 166 that Voss and Waller used anchors hoisted aloft to ease their boats' motions. Once again, the CSF should be used as a pointer as to whether more in investigation is in order, not as a be all and end all evaluation of capsize resistance. Generally the best way to use the formula for the lightship weight with and aboard but no water, or other . This should give you the most conservative number. Generally as you load the boat you will keep the weight low so roll moment of inertia increases with little or no decrease in general stability. If you are not loading the boat this way, you should give some thought to doing so. I would not expect the CSF to with the Macgregor boats, they rely on water ballast and the assumptions about ballast location and roll moment of interia that went into the CSF do not apply. There are actually 2 distinct 27' hulls, the Cat27 and the Cat270. The 270 is wider and lighter which would give a higher CSF number. A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it. 17-03-2012, 17:39   Boat: Bristol 38.8 is sticking stright up in the air. That's why cats become expensive life rafts when inverted, and why those modern monohulls with big fat (and flat) arses scare me. 17-03-2012, 18:01   Boat: Wauquiez Centurion 32 (1.68)with 30 (1.67) for example. It doesn't take into account where the weight of the ballast is located, nor any other weights for that matter. Nor does it take into account ballast ratio. A heavily built boat with a low ballast/disp ratio could well have a better (lower) number than a strongly built but not overweight boat with a higher ballast/disp ratio. For many of the lighter boats with bulb keels we see today it is entirely useless. For example the Pogo 10.50 has a CSFormula of 2.57 but is Category A and has self righting ability well beyond many boats with a CSF or less than 2. Any formula that only looks at beam and displacement is very limited in usefulness. As far as 1000lbs high up a mast yes an exaggeration. But if you take a boat with a CSF that is considered good, say 1.8, and load it up with on or anywhere above the waterline for that matter its CSF would, if weighed again be better than before it was wrongly loaded. An actual righting curve showing the angle of vanishing stability is a lot more meaningful. But while that shows the ability to recover from a wave induced capsize it has no real bearing on capsize from a breaking wave in the first place if the wave is large enough. And size does make a difference. From US Sailing:     17-03-2012, 21:56   Boat: Cal 20 (1.68)with 30 (1.67) for example. It doesn't take into account where the weight of the ballast is located, nor any other weights for that matter. Nor does it take into account ballast ratio. A heavily built boat with a low ballast/disp ratio could well have a better (lower) number than a strongly built but not overweight boat with a higher ballast/disp ratio. For many of the lighter boats with bulb keels we see today it is entirely useless. For example the Pogo 10.50 has a CSFormula of 2.57 but is Category A and has self righting ability well beyond many boats with a CSF or less than 2. Any formula that only looks at beam and displacement is very limited in usefulness. As far as 1000lbs high up a mast yes an exaggeration. But if you take a boat with a CSF that is considered good, say 1.8, and load it up with gear on deck or anywhere above the waterline for that matter its CSF would, if weighed again be better than before it was wrongly loaded. An actual righting curve showing the angle of vanishing stability is a lot more meaningful. But while that shows the ability to recover from a wave induced capsize it has no real bearing on capsize from a breaking wave in the first place if the wave is large enough. And size does make a difference. 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Order Reprints Print Article The British-flagged luxury yacht The Bayesian capsized early Monday off the coast of southern Sicily with 22 people aboard. Here's what is known about the 12 passengers and 10 crew members, believed to have hailed from Canada, France, Ireland, Myanmar, New Zealand, Sri Lanka, the UK and the United States. British tech tycoon Mike Lynch and his 18-year-old daughter Hannah Lynch are among those unaccounted for, according to Italy's Civil Protection Agency. Lynch, once dubbed the British "Bill Gates", founded software firm Autonomy in the 1990s but its $11 billion sale to Hewlett-Packard in 2011 saw him face fraud charges in the United States. A jury in San Francisco acquitted the 59-year-old and a co-defendant of all charges in June. It is understood he organised the yacht trip as a post-trial celebration for family, as well as some of his lawyers and employees. His missing daughter was set to study English at Oxford University after finishing school this year, The Times reported. Jonathan Bloomer, the 70-year-old British chairman of Morgan Stanley International, and his wife Judy, a charity trustee, are also among those missing, UK insurer Hiscox said Tuesday. American lawyer Chris Morvillo -- a partner at the high-profile Clifford Chance law firm, who worked on Lynch's recent US fraud trial -- is also missing along with his wife Neda. Confirming the pair were not accounted for in a statement Tuesday, a Clifford Chance spokesperson said: "We are in shock and deeply saddened by this tragic incident." The body of one man was found in the sea a few hours after the disaster unfolded off Porticello, east of Palermo. Officials have said he was the yacht's chef, with different media outlets naming him as either Ricardo or Recaldo Thomas. He is reportedly Canadian-born, and had been living in Antigua. Lynch's 57-year-old wife, Angela Bacares, who is also Hannah's mother, was among the survivors, officials have confirmed. She was seen in a wheelchair after suffering abrasions on her feet, according to the Italian newspaper La Repubblica. The paper reported she had been taken to a regional hospital, where she told doctors the boat began to tilt at around 4:00 am local time, waking Bacares and her husband. She had then climbed up to the deck to assess the situation when the vessel suddenly started to capsize, the paper said. Briton Charlotte Golunski, 35 -- a partner at Lynch's investment firm Invoke Capital who previously worked at Autonomy -- her partner James Emslie, and her one-year-old daughter also survived. Golunski told La Repubblica they made it out alive because they were on deck when the yacht sank, describing in dramatic detail holding her baby above the surface of the sea to save her. She said a lifeboat then inflated and 11 people eventually climbed in, with all three family members unharmed. Ayla Ronald, 36, a London-based lawyer for Clifford Chance originally from New Zealand who also worked on Lynch's fraud case, "thankfully survived the incident", the law firm confirmed. It noted her partner, believed to be named Matthew Fletcher, also made it out alive. Her father Lin Ronald told various media outlets that she had texted him that they were "very shocked at the moment". Other media reports have said another New Zealander, James Caulfield, 51, survived. Meanwhile Irish citizen Sasha Murray, 29, injured her right foot in the tragedy, according to the Irish Times. Frenchman Matthew Griffith, 22, is also said to have survived. The boat's crew are believed to include Sri Lankans, as well as a citizen of Myanmar named as 39-year-old Myin Htun Kyaw, according to reports. An error has occurred, please try again later. 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The British-flagged luxury yacht The Bayesian capsized early Monday off the coast of southern Sicily with 22 people aboard. Here's what is known about the 12 passengers and 10 crew members, believed to have hailed from Canada, France, Ireland, Myanmar, New Zealand, Sri Lanka, the UK and the United States. - Missing - British tech tycoon Mike Lynch and his 18-year-old daughter Hannah Lynch are among those unaccounted for, according to Italy's Civil Protection Agency. Lynch, once dubbed the British "Bill Gates", founded software firm Autonomy in the 1990s but its $11 billion sale to Hewlett-Packard in 2011 saw him face fraud charges in the United States. A jury in San Francisco acquitted the 59-year-old and a co-defendant of all charges in June. It is understood he organised the yacht trip as a post-trial celebration for family, as well as some of his lawyers and employees. His missing daughter was set to study English at Oxford University after finishing school this year, The Times reported. Jonathan Bloomer, the 70-year-old British chairman of Morgan Stanley International, and his wife Judy, a charity trustee, are also among those missing, UK insurer Hiscox said Tuesday. American lawyer Chris Morvillo -- a partner at the high-profile Clifford Chance law firm, who worked on Lynch's recent US fraud trial -- is also missing along with his wife Neda. Confirming the pair were not accounted for in a statement Tuesday, a Clifford Chance spokesperson said: "We are in shock and deeply saddened by this tragic incident." The body of one man was found in the sea a few hours after the disaster unfolded off Porticello, east of Palermo. Officials have said he was the yacht's chef, with different media outlets naming him as either Ricardo or Recaldo Thomas. He is reportedly Canadian-born, and had been living in Antigua. - Survivors - Lynch's 57-year-old wife, Angela Bacares, who is also Hannah's mother, was among the survivors, officials have confirmed. She was seen in a wheelchair after suffering abrasions on her feet, according to the Italian newspaper La Repubblica. The paper reported she had been taken to a regional hospital, where she told doctors the boat began to tilt at around 4:00 am local time, waking Bacares and her husband. She had then climbed up to the deck to assess the situation when the vessel suddenly started to capsize, the paper said. Briton Charlotte Golunski, 35 -- a partner at Lynch's investment firm Invoke Capital who previously worked at Autonomy -- her partner James Emslie, and her one-year-old daughter also survived. Golunski told La Repubblica they made it out alive because they were on deck when the yacht sank, describing in dramatic detail holding her baby above the surface of the sea to save her. She said a lifeboat then inflated and 11 people eventually climbed in, with all three family members unharmed. Ayla Ronald, 36, a London-based lawyer for Clifford Chance originally from New Zealand who also worked on Lynch's fraud case, "thankfully survived the incident", the law firm confirmed. It noted her partner, believed to be named Matthew Fletcher, also made it out alive. Her father Lin Ronald told various media outlets that she had texted him that they were "very shocked at the moment". Other media reports have said another New Zealander, James Caulfield, 51, survived. Meanwhile Irish citizen Sasha Murray, 29, injured her right foot in the tragedy, according to the Irish Times. Frenchman Matthew Griffith, 22, is also said to have survived. The boat's crew are believed to include Sri Lankans, as well as a citizen of Myanmar named as 39-year-old Myin Htun Kyaw, according to reports. Recommended Stories Mike lynch, recently acquitted in hp-autonomy fraud case, is missing after yacht capsized off sicily (updated). Original article continues below. Mike Lynch, the investor and high-profile founder of U.K. tech firm Autonomy, has been declared missing at sea after the yacht he was on, the Bayesian, capsized in a storm off the coast of Sicily early Monday morning. Lynch's wife, Angela Bacares, is one of the 15 who have been rescued. Taylor Swift, Beyonce, Dolly Parton and more artists featured during DNC Roll Call From Taylor Swift to Sabrina Carpenter, the DNC ceremonial roll call featured hit tracks from several artists. Fire breaks out at Cowboys training camp hotel in California, with no reported injuries The fire broke out in a condominium as the Cowboys conducted a training-camp walk-through. 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Waymo director says the company's cars won't honk at each other anymore Waymo's self-driving cars have finally stopped honking at each other in the middle of the night. Latest News Emergencies Environment Ask the Law Visa+Immigration Phone+Internet Reader Queries Safety+Security Banking & Insurance Corporate Tax Travel & Tourism Corporate News Electronics Home and Kitchen Consumables Saving and Investment Budget Living Expert Columns Community Tips Cryptocurrency Cooking and Cuisines Guide to Cooking Art & People Friday Partner Daily Crossword Word Search Philippines Australia-New Zealand Corrections Special Reports Pregnancy & Baby Learning & Play Child Health For Mums & Dads UAE Success Stories Photos & Videos Course Reviews Learn to Play Schedule | Medal Tally South Indian Health+Fitness Best Of Bollywood Entertainment Special Features Gratuity Calculator Notifications Prayer Times What is fate of 22 people aboard capsized yacht? World europe. British ‘Bill Gates’, Morgan Stanley boss among missing LONDON: The British-flagged luxury yacht The Bayesian capsized early Monday off the coast of southern Sicily with 22 people aboard. Here’s what is known about the 12 passengers and 10 crew members, believed to have hailed from Canada, France, Ireland, Myanmar, New Zealand, Sri Lanka, the UK and the United States. Get exclusive content with Gulf News WhatsApp channel British tech tycoon Mike Lynch and his 18-year-old daughter Hannah Lynch are among those unaccounted for, according to Italy’s Civil Protection Agency. Lynch, once dubbed the British “Bill Gates”, founded software firm Autonomy in the 1990s but its $11 billion sale to Hewlett-Packard in 2011 saw him face fraud charges in the United States. UK tech tycoon Mike Lynch missing after yacht sinks off Sicily Search continues for two missing footballers in northern Morocco Morgan Stanley boss, his wife among missing in yacht disaster as fresh search for 6 launched A jury in San Francisco acquitted the 59-year-old and a co-defendant of all charges in June. It is understood he organised the yacht trip as a post-trial celebration for family, as well as some of his lawyers and employees. His missing daughter was set to study English at Oxford University after finishing school this year, The Times reported. Jonathan Bloomer, the 70-year-old British chairman of Morgan Stanley International, and his wife Judy, a charity trustee, are also among those missing, UK insurer Hiscox said Tuesday. American lawyer Chris Morvillo — a partner at the high-profile Clifford Chance law firm, who worked on Lynch’s recent US fraud trial — is also missing along with his wife Neda. Confirming the pair were not accounted for in a statement Tuesday, a Clifford Chance spokesperson said: “We are in shock and deeply saddened by this tragic incident.” The body of one man was found in the sea a few hours after the disaster unfolded off Porticello, east of Palermo. Officials have said he was the yacht’s chef, with different media outlets naming him as either Ricardo or Recaldo Thomas. He is reportedly Canadian-born, and had been living in Antigua. Lynch’s 57-year-old wife, Angela Bacares, who is also Hannah’s mother, was among the survivors, officials have confirmed. She was seen in a wheelchair after suffering abrasions on her feet, according to the Italian newspaper La Repubblica. The paper reported she had been taken to a regional hospital, where she told doctors the boat began to tilt at around 4:00 am local time, waking Bacares and her husband. She had then climbed up to the deck to assess the situation when the vessel suddenly started to capsize, the paper said. Briton Charlotte Golunski, 35 - a partner at Lynch’s investment firm Invoke Capital who previously worked at Autonomy - her partner James Emslie, and her one-year-old daughter also survived. Golunski told La Repubblica they made it out alive because they were on deck when the yacht sank, describing in dramatic detail holding her baby above the surface of the sea to save her. She said a lifeboat then inflated and 11 people eventually climbed in, with all three family members unharmed. Ayla Ronald, 36, a London-based lawyer for Clifford Chance originally from New Zealand who also worked on Lynch’s fraud case, “thankfully survived the incident”, the law firm confirmed. It noted her partner, believed to be named Matthew Fletcher, also made it out alive. Her father Lin Ronald told various media outlets that she had texted him that they were “very shocked at the moment”. Other media reports have said another New Zealander, James Caulfield, 51, survived. Meanwhile Irish citizen Sasha Murray, 29, injured her right foot in the tragedy, according to the Irish Times. Frenchman Matthew Griffith, 22, is also said to have survived. The boat’s crew are believed to include Sri Lankans, as well as a citizen of Myanmar named as 39-year-old Myin Htun Kyaw, according to reports. More From Europe King Charles III meets survivors of child stabbings Alain Delon's pet dog saved from euthanasia Yacht capsized: Lynch, Morgan Stanley boss feared dead Mpox ‘not the new COVID’, says WHO Flexible work hours to ease peak traffic in Kuwait 70,000 jobs on new Saudi unified employment platform Biometric fingerprinting nets hundreds of outlaws Sharjah inmates’ children receive school bags,supplies Back-to-school uae: suppliers warned against price hike, iran: bus carrying pakistan pilgrims crashes, 28 killed, freelancers have more time for tax registrations, dnc 2024: obama says us ready for a harris presidency. Get Breaking News Alerts From Gulf News We’ll send you latest news updates through the day. You can manage them any time by clicking on the notification icon. 126 IMAGES Capsize Transverse stability: sailing yachts at sea, wave impacts, knock-downs What Is Capsize Ratio And How Is It Calculated? Understanding Sailboat Design Ratios Capsize Screening Formula for Boats and How to Measure It What is a Sailboat Capsize Ratio and how to measure it COMMENTS What is a Sailboat Capsize Ratio and how to measure it Here is a summary of what a sailboat capsize ratio is. A sailboat capsizes ratio is a parameter used to show whether a boat can recover from an inverted, capsized position or not. This term was mainly developed after the Fastnet race disaster. This was a 1979 race where a storm destroyed several yachts during the last day of the race, also ... What Is Capsize Ratio And How Is It Calculated? Capsize ratio is a term used to describe the likelihood of a sailboat recovering after it has capsized. It gives an indicator as to whether or not the boat will right itself after being fully inverted. This term was developed after the tragic Fastnet race disaster in 1979, where a storm destroyed several yachts and caused 19 deaths at sea on ... Capsize Screening Formula for Boats and How to Measure It If the ratio exceeds 2.0, the boat may have reduced stability and a higher risk of capsizing. Interpreting the Result: GM/B ≤ 2.0: The boat is considered to have adequate stability based on the capsize screening formula. ... Knowing a boat's capsize screening number raises awareness of its stability limits. Boaters can avoid overloading the ... What is Capsize Screening Formula (CSF)? The Capsize Screening Formula is an attempt to validate if a given yacht is suitable to participate in an ocean race. Such validation became obvious after the Fastnet race in England in 1979 was hit by a storm that shredded the race fleet. Of 303 yachts, 85 finished, 75 capsized, and five sank. 15 yachtsmen died. Understanding Sailboat Design Ratios D/L Ratio = D/(0.01L) 3. Where D is the boat displacement in tons (1 ton = 2,240lb), and L is the waterline length in feet. The Sail Area/Displacement Ratio ... BR = (B/D) x 100. Where B is ballast in lbs, and D is displacement in lbs. The Capsize Screening Formula. CSF = 3 √(Bm/D) Where Bm is the maximum beam in feet, and D is displacement ... Sailboat Guide Ballast / Displacement Ratio. A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize. Sailboat Calculator PART 3: RATIO RESULTS BOX. Results: This area displays the parameters of the boat selected. Do not enter values here. Click on any of the Derived Quantities boxes for an explanation of the box ... Capsize Screening Formula: S#: Hull Speed: Pounds/Inch Immersion: RIG MEASUREMENTS: SA Fore: SA Main: SA Total: (100% Fore and Main triangles) How to Choose a Safe Cruising Sailboat Capsize Screening # = Boat's Max. Beam (feet) / Cube Root (Gross Displacement / 64) In English: take the boat's gross displacement in pounds, divide it by 64 and then take the cube root of the quotient. Now, divide the boat's maximum beam in feet by the cube root figure. The resulting number should be 2 or less. Capsize screening formula The capsize screening formula (CSF) is a controversial method of establishing the ability of boats to resist capsizing. It is defined for sailboats as: Beam / ((Displacement/64.2) 1/3), with Displacement measured in pounds, and Beam in feet.A lower figure supposedly indicates greater stability, however the calculation does not consider factors such as hull shape or ballast. Comfort, Capsizing, and SailCalc The comfort ratio formula is as follows: Displacement in pounds / (.65 x (0.7 LWL + 0.3 LOA) x B^1.333). Brewer says ratios vary from 5.0 for a light displacement daysailer to the high 60.0's for a super heavy ocean cruiser. Next, let's define the "Capsize Screening Formula" (CSF), a sometimes controversial mathematical equation that is suppose ... Capsizing Seawise University capsized after being gutted by fire in 1972. Capsizing or keeling over occurs when a boat or ship is rolled on its side or further by wave action, instability or wind force beyond the angle of positive static stability or it is upside down in the water. The act of recovering a vessel from a capsize is called righting.Capsize may result from broaching, knockdown, loss of ... Comparing capsize and comfort rates of boats For example: Capsize Ratio = Beam / (Displacement / 64)**0.333 Notice the only factors involved are Beam and Displacement. This means that, for the same displacement, a boat with a light-weight construction and a deep fin keel will have the same number as boat with heavy construction and a shoal-draft keel. Capsize Ratio formula is the maximum beam divided by the cube root of the. displacement in cubic feet: Capsize Ratio = Beam/Displacement.333. The displacement in cubic feet can be found by dividing the. displacement in pounds by 64. The boat is acceptable if the result of the calculation is 2.0. Sailboat Specifications 101: Explained For Beginners It is the ratio of a boat's displacement (weight) to its Beam (width). Capsize ratio formula: Beam / ( (Displacement/64.2)1/3) The beam is in feet. Displacement is in pounds. A good capsize ratio is generally considered to be between 1.33 and 2.0, although this can vary depending on the type of boat and its purpose. Numbers geek specifically capsize formulas don't know the capsize ratio of the Catalina 30, but you're more likely to lose the mast or rudder first, which would then are more of a concern- and would change the capsize ratio. ... If you asked 10 sailors in a bar what the capsize ratio was for their boat, at least 9, myself included, would shrug. "Just call me TB" Save Share. Like ... Capsize Capsize screening formula. The maximum beam divided by the cube root of the displacement in cubic feet, or Maximum beam (feet) = less than 2 3÷Displ/64 The displacement in cubic feet can be found by dividing the displacement in pounds by 64. Safe Sailing: How to Choose A Safe Sailboat The answer you get is known as the boat's Capsize Screening Number. If that number is two or less, the boat passes this important safety test. In general, anything over 2 is a failing score and indicates the boat's stability is questionable. In rough sailing conditions, a boat with a failing capsize screening rating is at heightened risk of ... Capsize screening formula It is one of many factors I consider. As I add for-sale boats to my comparison spreadsheet, higher comfort and lower capsize numbers improve the calculated overall rating. The boat ranked 4th right now is a Beneteau 381, which has the worst comfort (22.2) and capsize (2.1) ratings of the top 10 on my list. Its age, price and location helped boost its overall rating. Capsize Ratio's Re: Capsize Ratio's. The Capsize Screening Formula is a quick and dirty formula for indicating whether a naval architect should do more analysis of a boat's capsize resistance. The more involved analysis looks at the roll moment of inertia of a boat to determine its susceptibility to capsize due to wave action. What Is Fate Of 22 People Aboard Capsized Yacht? The British-flagged luxury yacht The Bayesian capsized early Monday off the coast of southern Sicily with 22 people aboard. Here's what is known about the 12 passengers and 10 crew members ... What is fate of 22 people aboard capsized yacht? The British-flagged luxury yacht The Bayesian capsized early Monday off the coast of southern Sicily with 22 people aboard.Frenchman Matthew Griffith, 22, is also said to have survived. What is fate of 22 people aboard capsized yacht? Morgan Stanley boss, his wife among missing in yacht disaster as fresh search for 6 launched A jury in San Francisco acquitted the 59-year-old and a co-defendant of all charges in June. catamaran gulet motorboat riverboat sailboat trimaran yacht