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nero : KD860 catamaran by K-Designs

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Saw this design and thought it was interesting from the ease of construction but wasn't sure if the flat bottom was a shot in the foot when it came to performance. What are your thoughts on the KD860 catamaran design and why did you go with building something different? Great hull by the way in your pics with the tractor.

I came across this design and the designer a few years after I did my own design. As the result of my efforts, I think/thought I needed a longer waterline to circumnavigate with. Strip planked hulls have many advantages. Speed of construction vs. pannel construction is not one of them. My project is still alive, but building has slowed a bit. My work days are a bit shorter and other responsibilities have complicated the straight forward days at the start of my project. At present, one hull is strip planked and glassed on the inside. Everything is in place to bond the two halves together. (ran out of warm weather) The pieces match up! I still have one half of one hull to strip plank. Before this can be done I have to bond the above halfs and glass part of the outside. And there is the keelson to add in also. I have three months to wait of the cold weather. Will start working on the bridge deck engineering before then.

• Category: Sailboats - Multihull Uploaded By: nero Date: Feb 10, 2006 View Count: 18,042 Comment Count: 2
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Gemini 105 Review

• Post author By River B
• Post date October 24, 2020
• 3 Comments on Gemini 105 Review

No catamaran discussion would be complete without a nod to the 34’ Gemini 105M and 105 MC line of catamarans, created by designer Tony Smith. From modest beginnings in 1996, the Gemini 105 has become one of the most popular domestic-built catamarans in the United States, with over 1200 hulls splashed.

Gemini Catamaran History

Originally built in Maryland, the Gemini 105 model began with the 105M (meaning 10.5 meters) in 1995 and then a design change in 2004 to the 105MC, some notable differences being the extended cockpit cover to allow for a full enclosure and a slightly taller mast (while still remaining ICW-friendly). In fact, the “C” in the 105MC stands for “convertible,” likening the cockpit to that of a sports car.

Gemini production moved to FL in 2009 after the 2008 financial meltdown. In 2011, Gemini offered the Limited-Edition Design Touch TM models, whose upgrades included cherry veneer finishes, Corian countertops, and ducted air conditioning. In a partnership with Hunter Marine and a generous buyout from The Catamaran Company, Gemini was able to live on under the direction of Smith’s daughter, Laura building the 105 until 2012. Catalina on the west coast for Florida took over production of the Legacy 35 in 2015, which is still in production today.

While the Gemini 105 hasn’t won any official awards, according to SAIL Magazine, “[i]f there ever was a sub-40ft cat that should be included in an imaginary ’Catamaran Hall of Fame,’ it would have to be the Gemini 105.”

The Gemini 105s were designed to be affordable, compact, relatively easy vessels for sailors new to catamarans. In the performance – comfort — cost trifecta, there is a definite favor towards cost, which can equate to quality issues. However, Gemini owners swear by their performance and aspects of comfort.

Let’s see what they highlight.

• Narrow Beam. With a beam of 14’, the Gemini can tuck into a standard slip, lowering the cost of ownership and reducing haulout hassles that other catamaran owners sometimes face.
• Shallow Draft. With kick-up centerboards and rudders, and outboards (or drive legs) that can raise up, Gemini owners can anchor in as little as 2’ of water. Crowded beach anchorages are seldom an issue for these vessels, which can tuck in well away from other deeper-draft cats and monohulls alike.
• Livability . The 3-cabin layout provides both comfort and privacy and the wet head is huge for a small boat. The C-shaped settee converts into a large bed for passages or extra guests. The large, propane-powered refrigerator provides ample space for food and beverages without draining batteries. With 6’ of headroom inside and up to 6’7” of headroom in the cockpit, guests can enjoy the panoramic windows without stooping.
• Speed . While the Gemini 105 won’t be breaking any circumnavigation records, for her size, she’s fast—able to achieve 40-50% of wind speeds and the ability to point at about 50 degrees (apparent) to wind. According to Mark Baummer, on SV Argo, the Gemini 105 can easily hit speeds of 8 knots and he regularly logs double-digit speeds. More on why that may be in a moment.
• Engine Accessibility. Whether equipped with an outboard or the Westerbeke 30b3 diesel, accessibility is far and above that of most other smaller (and even some larger) catamarans on the market.

Gemini 105 Hull Construction

The Gemini 105 generally took about 5-7 days to produce, utilizing vinylester resins to bond a barrier coat of 1.5-ounce mat. Next comes two layers of 18 x 15 Cofab mat. The foredeck and cabin top are cored with 1/2″ end-grain balsa, as are cockpit areas in which there are no deck fittings.

The hull-deck joint is a shoebox design bonded with something the designer calls “black poly putty, which cures fast, using a chemical process, rather than an air-dry process. The deck is then secured with stainless steel fasteners on 5″ centers. The joint is covered by a gunwale guard.

Performance Factors

Catamaran designers utilize a broad number of theories in their attempts to achieve performance. For Gemini, this means a 9:1 length to width ratio, with a shallow and fat tear-drop shape intended to increase both speed and load-carrying capacity. Although, with only 18” of bridgedeck clearance, you’ll want to utilize that space sparingly, or risk losing any performance benefits you may have.

Centerboards and sail plan contribute to the cat’s ability to sail closer to the wind than most production catamarans out there.

Is the Gemini 105 a Serious Ocean Cruiser?

Tony Smith and his son Neil took a Gemini 105 through the northern Atlantic passage from Florida to England on a 23-day trip where they encountered 45-knot winds and 35-foot waves . Neither felt unsafe, but they also swore they would never make the trip again!

SV Tere Hau Nui was a 2003 Gemini 105MC that was sailed across the Pacific to Fiji. Again she was sold via our for sale by owner services in 2012. The new owner sailed her to Australia where she unfortunately dragged onto a rocky shore . The new owner, Brian, bought her back from the insurance company and has fixed her up. He splashed her again in 2020.

SV Slapdash is a 2004 Gemini 105Mc that circumnavigated, albeit with reported frequent stops to perform repairs and modifications. The owner sold by advertising on this website in 2012.

Cruising “celebrity” Carolyn Shearlock (of The Boat Galley fame), owner of SV Barefoot Gal, a Gemini 105M, cruises Florida and the Bahamas, but says she wouldn’t take the vessel offshore.

Mark Baummer, owner of SV Argo , sails his 1999 Gemini 105M in the Chesapeake Bay and offshore to New England, says he would feel comfortable taking the Gemini offshore. He confirms the boat is noisy when underway, saying, “it’s annoying, but you get used to it.” He also noted a great deal of flexibility in the hulls and the main bulkhead pieces working against each other. After a conversation with the designer, he was assured that this is “normal and helps to relieve racking stress on the boat.”

Gemini 105 owner John Grossenbacher says he crossed the Gulf Stream with 18-20 kt NE winds and 4-6′ seas. He reports sailing at 8-9 kts while cooking dinner with a glass of wine sitting on countertop—the classic catamaran marketing brochure image, right?

Like any vessel, it’s really a matter of personal preference, seamanship capability, and the stomach to put up with the chaos that the ocean can throw at you. For my money, I’d stick to coastal cruising on the Gemini. But that’s just me.

The Wish List

Gemini 105 owners love their boats, but there are always things that they wish were different or done better. Here’s what they have to say about that:

• The Gelcoat – gelcoat crazing is common on the Gemini 105
• Soft, leaky decks – as you’ll recall, the decks are balsa-cored, so water intrusion can take its toll on these vessels, so be proactive about re-bedding deck hardware, particularly around hatches and stays.
• Close – quarter maneuverability – while Carolyn Shearlock finds the Gemini 105M to perform better in close quarters than her Tayana 47, many find the Gemini, with its single engine, to be a bit squirrely in tight situations.
• Slightly Under-canvassed – under light winds, the Gemini has trouble, but over 10 knots and she sails beautifully.
• Forward Visibility – from the cockpit, the view forward is slightly challenging.
• Centerboard Rot – the original centerboards are prone to rot and worms. Baummer’s centerboards both fractured while on an offshore passage (the boat was fine, but didn’t point as well, as to be expected).
• Westerbeke 30b3 – this diesel gets mixed reviews and the company that services the drive leg have gone out of business and there is no clear source for parts.Many owners opt to replace the diesel with an outboard.
• Slamming – there may be no clear answer to this issue given the overall design, but some wish for a wave diverter under the bridgedeck to break up the waves.
• Inaccessible Wiring and Plumbing – with wiring looms attached to the liner prior to attachment of the liner to the hull, it’s virtually impossible to access without some level of destruction.

As these boats are not being produced anymore, these are some things to think about if you plan a refit. Many owners like that the boat is easy to work on (perhaps save the wiring), and at the size of the vessel, those who are handy can do a refit on the (relative) cheap.

The Bottom Line

Described by its designer as “the couple’s catamaran,” the Gemini 105 models are designed to be an introductory catamaran for former mono-hullers. Those who are looking for a coastal-cruising catamaran on a monohull budget might want to give the Gemini 105 some consideration.

• Tags Catamaran Interviews , Catamaran Reviews

River is a licensed USCG Captain with a lifetime of experience on the water. From the San Francisco Bay to the South Pacific, blue water to clear water, he’s sailed a wide variety of catamarans and crawled around in the bilges of more than he can count. You can follow his misadventures at www.tilted.life.

3 replies on “Gemini 105 Review”

I need an owners manual for this boat. Specifically the page that lists all the line lengths and guages.

The boat is in Panamá.

These are from the Gemini Owners Group .

Gemini 105 M Owners Manual Gemini 105 MC Owners Manual

I’d like to replace my sails, what are the sail dimensions for a Gemini M105?

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Unveiling the Ultimate Luxury: A 105-Foot Custom Catamaran with an Unforgettable Pool Nestled Between its Twin Hulls

Granocean’s new flagship X-32M utilizes the abundant space offered by multihulls, providing both superior space above and below deck compared to monohulls. The Australian outfit’s largest custom power catamaran to date, a magnificent 105-footer is set to impress with a multitude of luxurious amenities, ensuring an entertaining and enjoyable experience for seafarers.

Currently being constructed at Granocean’s Chinese facility on the Pearl River Delta, the X-32M is commissioned by a returning client who has a passion for global cruising. This versatile vessel is designed to excel in terms of both power and seakeeping capabilities, allowing it to navigate various waters with ease.

The X-32M will be equipped with two Caterpillar engines, offering a cruising speed of 11 knots and a remarkable top speed of 17 knots. While specific details about its range have not been disclosed by the yard, this powerful propulsion system ensures efficient and reliable performance on the water.

Under the leadership of Eric So, the in-house design team at Granocean has skillfully crafted the exterior and interior of the X-32M. The exterior design showcases sleek lines, prominent twin hulls, and a stylish all-white color scheme, creating a visually striking appearance. On the inside, the light and airy atmosphere is accentuated by the presence of expansive windows, allowing ample natural light to illuminate the contemporary furnishings and design elements. Catamaran

Boasting an impressive 39-foot beam, the X-32M offers a spacious layout that includes a generous main salon, along with adjoining dining and relaxation areas. When it comes to accommodation, this luxury yacht features a vast owner’s suite complete with an office, lounge, and outdoor deck, in addition to two VIP suites and three staterooms. With these arrangements, the X-32M can comfortably accommodate up to 12 overnight guests. The yacht also provides crew cabins located in the hulls, ensuring a comfortable and convenient space for the onboard staff.

In addition to its remarkable features, the X-32M includes garages located towards the aft of each hull, providing ample space to store various water toys and tenders. Adding to its allure, a stunning swimming pool is situated on the foredeck, positioned transversely between the two hulls. This captivating yacht further boasts a cinema for onboard entertainment and a fully equipped gym for fitness enthusiasts. These exceptional amenities contribute to an unforgettable experience aboard the X-32M.

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Privilege Series 5

Description

The Privilege Series 5, which has been rebranded the 510, is a luxury long distance cruiser that has made a name for itself thanks to its quality build and finish. These boats are a real step up from other cruising catamarans which is why we have included them in our Luxury Catamarans sections. There is an associated jump in price of course.

This boat has been well thought out with wide, easy-to-navigate side decks and plenty of hand holds. and you can tell very quickly that she was designed for long passages. The helm, engine controls, instruments and electric sheet winches are all around the raised helm station that should make her easy to sail with a short-handed crew. Visibility is good all around from the elevated helm position on the port side.

The hulls, deck, cabin top and bimini are foam-cored and resin-infused, and to reduce weight, furniture and bulkheads are made with foam-cored maple laminates. The quality of the joinery finish is a real step up from less expensive boats, as you would expect.

The Privilège Series 5 has rounded hulls, with chines above the waterline for decent living space down below and buoyancy at sea. She feels like a very solid boat under power or motor and is very quiet below. On a reach, you should comfortable hit 9 or 10 knots in a decent breeze.

There’s a full main and genoa, and an inner stay-sail, also with a furler, plus options on light wind and down wind sails off the bowsprit. The new angular lines of the updated Marc Lombard design look like they will cut through a sea- she’s an impressive looking catamaran.

Cruising speed under power is around 8 knots

It’s probably the interiors that Privilege are so well known for and it was Franck Darnet who had his hand in designing this one. These are semi-custom boats so owners have a great deal of input into the configuration of individual boats. The signature feature is the huge master stateroom in the nacelle forward- it’s probably the biggest owners cabin in its class and many lead onto a big ensuite bathroom in the starboard hull (I can’t quite call it a head).

Privilege was started in the 80s by Philippe Jeantot, and launched as a safe family cruising and offshore catamaran. The Privilège Serie 5 ticks all of these boxes. If you are looking for a solid, safe long distance cruiser with the space and ability to soak up all of the toys, then the Privilege Series 5 is your boat.

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• Sailboat Reviews

Gemini 105Mc

This is the third version of an already thoughtful design that tony smith has been tweaking for years. it's a spacious, stable platform for a fast-cruising couple..

Tony Smith’s most recent design is the third iteration of a 34-foot catamaran that his company, Performance Cruising, Inc., of Annapolis, first introduced to the American market in the 1990s. The result of Smith’s continued tinkering, the 105Mc, is, he says faster than the original. Since this is our first review of the Gemini cat in any version, we can’t compare. But we can report that this boat is fast for a cruising catamaran. It’s also evidence that when a builder is willing to incorporate new and sometimes expensive ideas in design development, the results can be worth the investment.

Company History Tony Smith is a British expatriate who, with wife Susan, formed Performance Cruising in 1980. Following graduation from the University of East Anglia with a degree in engineering, he studied the mechanics of boat performance while participating in singlehanded races, including the first 2,100-mile Round Britain race, in which he finished fourth.

He began his boatbuilding career by constructing a 24-foot Piver trimaran in a shed in England. Then, in 1969, he developed a method of integrating foam coring with fiberglass, and produced the Telstar, a 26-foot, folding trimaran. During a 10-year run, 300 of the boats were sold worldwide. Along the way, he also was involved in the construction of 30- to 70-foot custom yachts.

Eventually emigrating to the US, he introduced the Telstar to the US market. Following the loss of the molds in a fire in 1981, he re-emerged on the scene with the design for a new catamaran, appropriately called the Phoenix, the first Gemini.

In 1993, the company launched the Gemini 3400, the first catamaran with a lifting underhung rudder system. It was eventually modified and reintroduced as the 105M, and the 105Mc is the most recent upgrade.

With 800 boats on the water, the company claims to be the best-selling catamaran manufacturer in the US. In 2002 the company’s 20 employees built and sold 54 boats, valued at $8 million, in a 16,000-square-foot factory. An additional 25,000 square feet of production space are currently under construction.

Six dealers are located in Florida, Maryland, California and Washington. Though the company also sells directly to customers, there’s no price advantage, and a connection to a local dealer would be an advantage if warranty issues arise.

A prototype for a new Telstar trimaran is undergoing sea trials, and can be seen on the Performance Cruising website.

Appearance/Design Smith’s perspective on sailing and yacht design fits the definition of a multihull advocate. From his standpoint, sailing is about speed, comfort, and stability.

From an aesthetic standpoint, comparisons of a 35-foot catamaran to a cruising monohull are usually akin to comparing a coupe to a delivery van. Though both may be designed to accomplish the same purposes, the execution varies greatly. Many cruising multihulls present a slab-sided appearance, and boxlike profiles with cabins extending high above deck level.

The 105Mc does not. When viewed from the quarter, the Mc has a relatively sporty appearance, even with the addition of a cockpit canopy that raises the boat’s profile. Viewed on the centerline, there’s no question she’s a cat, though the unsightly strakes of the 3400 version have been eliminated.

Smith says Gemini catamarans are designed for “serious ocean cruising,” adding that “a 23-day passage with son Neil across the North Atlantic opened my eyes to her capabilities.”

During the passage, he says, the pair encountered 45-knot winds and 35-foot waves, but never felt they were in harm’s way, and were comfortably ensconced in the cockpit wearing layers of fleece.

As most readers know, voyaging in multihulls offshore demands some different sailing techniques and priorities than sailing ballasted monohulls. The high initial stability of a multihull works both ways: the boat will mightily resist capsizing, but if it does go over and invert, it will be virtually impossible to right again without the assistance of a large ship with a cargo crane. Assuming the essential integrity of the hulls, the platform will be stable, and the crew will live in an inverted world pending rescue. However, very few owners of cruising multihulls have the occasion to take their boats into conditions that seriously challenge their initial stability, and (North Atlantic deliveries by designers notwithstanding) this Mc will usually be sailed in coastal or near-coastal waters.

The Mc has the same basic dimensions as the 3400. Note that the weights published in the company’s sales literature and on its website are at odds with each other. Dimensions in this article are accurate, Smith says: “The 105M and the Mc are the same weight—9,600 pounds. We realized after our trans-Atlantic trip that the weights we had given for the 105M were too low. We finally bought a pair of scales!

“The mast on the Mc is a foot taller than the 105M, and has a 1′ crane.” The mainsail now carries a large roach and full battens, increasing mainsail area from 260 to 340 square feet, a hefty jump. The 150% genoa carries 350 square feet.

A new option is a flat-cut overlapping genoa known in the multihull world as a “screecher.” This 490-square-foot sail produces spinnaker performance without adding a pole and guys.

The furling drum for the screecher tack can move athwartships on a curved track that is mounted at the prows of both hulls and across the bowsprit/anchor platform, forward of where the anchor is dropped through. This movable tack allows more flexibility with sheeting angles, especially when attempting to work to weather.

The cut of the sail allows it to be sailed to within 50 degrees of the apparent wind, and the tack arrangement doesn’t get in the way of the ground tackle.

Smith describes the hull shapes, introduced in 1995 on the 105M model, as “revolutionary in the multihull industry.” They have a 9:1 length to width ratio.

“They closely resemble a racing monohull,” Smith says. “They are shallow and fat, with a teardrop shape to produce more speed and increase load-carrying capacity. Compared to the 3400, narrower shapes allow hulls to be moved outward to produce stability without increasing beam.”

The foredeck has 39″ of clearance at the bow. (Note that the builders refer to the deck area forward of the cabin as the “bridge deck,” but we’ll use “foredeck” as we don’t want to confuse it with the bit of decking often found between the cockpit and the companionway.)

Asymmetric centerboards were designed to reduce turbulent drag and increase lift. Constructed of a combination of fiberglass mat and Kevlar surrounding closed cell foam, they pivot upward to allow shallow-water anchoring. Located in cavities on the hulls, they are raised from inside the main saloon, a convenient arrangement that does not interfere with galley or navigational chores. Smith says the combination of hull and centerboard redesigns produced a boat requiring “25% less energy to push it the same speed.”

The cockpit sole has been lowered slightly to increase headroom to 6′ 7″. However, the modification does not impair the helmsman’s view forward through a large Lexan window that spans the deck. The wheel was moved outboard, allowing the helmsman to steer from the rail. Mainsail controls are now located on a thicker transom that provides more comfortable seating for crew, and the stern has been modified to allow access from swim ladders.

Smith’s personality is that of a consummate tinkerer. However, unlike industry giants, he enjoys the luxury of being able to continually focus his attention on one product with an eye toward evolutionary improvements.

Deck One early impression while sailing this boat is that the cockpit doesn’t resemble a spaghetti factory, though the boat is as well-equipped with name-brand equipment as a similar-sized monohull.

Halyards are led to winches on the mast rather than sheetstoppers on the cabintop because, Smith says, “you’re operating on a stable platform, even in a blow,” so moving forward is not as treacherous.

The mast carries straight double spreaders and is stepped on deck atop the main bulkhead. The headstay is opposed by a split backstay with tensioner. Halyards are internal. Shrouds are dead-ended on chainplates at the main bulkhead. The chainplates are bolted through steel strapping bonded into the foredeck area.

The mast is rigged with permanent checkstays angled 20 degrees aft. These are supported through the deck by a stainless steel rod married to a steel plate mounted horizontally in the hull. The powerful sailplan is well supported.

As is true on most catamarans, movement forward is relatively effortless. The combination of 14″ wide steps, a handhold on the canopy, a stainless steel handrail recessed in the cabintop, and 10″ wide decks, allowed us to move forward safely in blustery conditions we encountered on a test sail.

The large sundeck and plastic seats attached to the forward rail provide passengers comfortable lounging spaces forward of the mast when underway. Unlike a lightweight monohull, the cat’s performance is relatively unaffected by weight on the foredeck. Storage compartments are located in each hull.

The helmsman steers seated on a 27″ wide x 16″ deep seat that affords unrestricted views forward. We sailed with three passengers under the canopy without interfering with the skipper. Though the saloon may be enclosed in stinky weather, clear windows on the top half of the cockpit bulkhead slide open to allow the driver to commiserate with passengers.

The mainsheet is attached to the end of the boom and a section of track mounted on the stern rail that affords excellent sail control. However, the task becomes difficult when the cockpit is enclosed by a clear vinyl cover.

Lockers for storage of propane tanks and an optional generator are also located in the cockpit.

Belowdecks Step over an 11″ doorframe into the saloon and there’s no comparing the open spaces of the Mc’s 14-foot beam to the view along the saloon of a typical 34-foot monohull. That impression is augmented by a portlight array that provides 360-degree visibility, and four Bowmar hatches that allow light and air to flow in from overhead.

Fiberglass surfaces are light and shiny, and veneers nicely finished. The fit of most cabinetry is above average.

The centerpiece of the saloon is a C -shaped dining area surrounded by cushions that, with the table removed, serves as a conversation pit. When lowered, the table converts to a double berth.

The space to port, amidships along the hull, is dedicated to the navigator. The master stateroom is forward amidships and to starboard, with the bunk set at a slight angle. The head is forward to port. There’s an elongated galley on the starboard side, matched by a navigator’s station along the port side, and twin staterooms aft.

The boat has enough bunks for 6-8 adults, but Smith rightly calls it “a couple’s boat.” This is a refreshing contrast to builders who overstate the livability of their products.

In addition to its spaciousness, the minimum headroom, even in the head, is more than 6′, so most passengers will be able to stand upright.

Though the interior is not dramatically different than typical production boats, several touches contribute to a favorable impression. The dining table is solid teak. Leaves increase the surface of the table to feed 6-8 adults, and it rotates 90 degrees to fit the crowd.

Part of the navigator’s 89″ long work surface is elevated and shaped so a chart kit fits securely.

Aft staterooms have a 28″ x 28″ area in which to change clothes without banging the hull. Both have double berths and opening ports. Propane sensors and fume detectors are standard equipment in the staterooms, as are audible alarms.

The size of the galley on the Mc was increased by locating countertops on the inboard and outboard sides of the passageway, and the addition of drawers and cabinets. Similarly, room for a built-in microwave was added. The space is filled with a Voyager 2000 two-burner stove with oven and broiler, and two-section stainless steel sink. A solar vent is located overhead. The four-cubic-foot refrigerator is a Dometic American.

Skipper’s quarters are filled with light by a port spanning the hulls that presents views through black Lexan. The queen-sized berth sits on an island with nothing below it but water. Storage is forward in the hull, and in bins to starboard. The aft bulkhead of the compartment is enclosed by smoked glass that slides out of the way to provide a view corridor for the helmsman.

The head compartment on the Mc is big, bright, and well-ventilated. A good touch is a siphon arrangement that allows fresh water to be pumped through the toilet after every use, helping to eliminate odors.

Throughout the catamaran, spaces are well-organized and proportioned, so crews will rest, eat, and sleep in comfort. The skipper’s quarters are large enough to help compensate for the monthly mortgage payment and slip fees.

Construction The Gemini plant is a model of efficiency, with no wasted space, as we learned during an afternoon tour. Boats typically require 5-7 days to proceed past six stations to a forklift waiting to launch them into a creek behind the facility.

Hulls, decks, and interior liners that provide reinforcement of the structure and a base for furniture are solid fiberglass. Liners are glassed and tabbed into the hull prior to installation of the deck.

The lamination schedule calls for vinylester resins bonding a barrier coat of 1.5-oz mat followed by two layers of 18 x 15 Cofab mat. The only coring is 1/2″ end-grain balsa across the foredeck and cabintop, and in cockpit areas in which there are no deck fittings.

The hull-deck joint is a shoebox design bonded with something Smith calls “black poly putty,” produced by Cook’s. Most builders prefer 3M5200 but Smith has used the putty for 20 years because “it has an 8- hour setup time that allows workers to be more precise in the placement of the two sections. It makes a phenomenal bond that is not brittle because it is chemically cured, a better alternative than air-cured products.”

Once installed, the deck is secured with stainless steel fasteners on 5″ centers and the joint is covered by a gunwale guard.

Following his trans-Atlantic trip, Smith decided that the boat needed to undergo a weight loss program. When constructed, most boats are heavier than designed, and the Mc was no exception. Smith estimates the boat was 1,000 pounds too heavy.

“It was not a matter of speed, but of comfort,” he said. “I felt that by reducing the boat’s weight I could increase its buoyancy and produce a more comfortable ride.”

To that end, he replaced drawers in the forward stateroom with bins, substituted 1/2″ plywood for 3/4″ in some areas, and lightened the lamination in some nonload-bearing areas.

The boat’s Achilles heel could be the solving of wiring or plumbing problems, should they occur. Wiring looms are attached to the liner prior to the installation of the liner to the hull, and are virtually inaccessible. Of the arrangement, Smith says “our looms are foolproof. Remember, we’ve been doing this for 20 years and the process is evolutionary, not revolutionary.” Spare hoses are installed during construction to ease retrofitting appliances, and 12-volt wires are run through PVC to avoid heat and chafe. Wires exit the mast into the forward stateroom, and can be accessed in a panel between the deck and liner. Still, we wouldn’t want to perform subcutaneous surgery on this boat.

Performance We sailed the 105Mc on the day after the Annapolis Boat Show ended, when multihull manufacturers congregate to offer rides to interested sailors. A northeaster arrived that morning, bringing winds that built to 25-35 knots and produced a 3-4 foot chop. We were the only multi hull on the water.

With the wind abeam when we slipped dock lines, once we were underway she motored well despite her windage. On the bay, the boat sailed with little heel, and fast, under a reefed mainsail and a flat, 90% jib. Nearby, the three-person crew aboard a 30-foot monohull struggled to keep their boat on her feet.

Sailing closed-hauled, speed fluctuated between 6.5 and 7 knots. The short chop produced a bumpy ride and water over the bow, but we stayed on course with very little leeway. When we cracked off, speed fluctuated between 7 and 12 knots in wind speeds ranging from 17 to 25 knots. She was easy to steer, and responsive when we made sudden maneuvers to avoid crab pots.

The canopy protects crew from the elements, but may provide a false sense of security, as we learned when we moved forward from its protection and stepped into a chilly breeze and seaspray. Handrails are well located, and the nonskid was effective on the wet deck.

The boat is propelled under power by a single Westerbeke diesel, using an outdrive leg than can be lifted clear of the water. The current standard engine is 27-hp, up from the 20-hp engine previously installed.

Conclusions This third generation of Gemini cat is an improvement over her predecessors. She sails as well to windward as can be expected of a cruising catamaran (better than many) and shows good speed and stability off the wind. She’s easy to operate, and well-built. Spaces belowdecks are comfortable and larger than those on similar-sized monohulls, though the lack of a second head will be an inconvenience for skippers overnighting with large crews. With the 27-hp engine, a 150% genoa and furler, and electronics, the tab for the 105Mc is $129,500. Add a screecher for another $5,400.

Contact – Performance Cruising, Inc., 410/626-2720, www.geminicatamarans.com

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Where is the production site, and can a tour of the facility be arranged?

The boat is no longer in production. Tony retired and sold the company. I think during the 2005 market crash everything fell apart. The outdrive and engine aren’t made anymore. The new owners redesigned the boat and ruined the original idea. They tried to design a boat for the single handed rental market in the Caribbean with a deeper draft and fixed keels. It didn’t sell well.

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Hello Chuck

It is some time ago that I wrote to you. As a keen reader of your unique magazine I admire the enthusiasm of your writer/readers a lot.

In the meantime I finished the design of the KD 860. A 28 ft long cruising catamaran. Again in the plywood/glass/epoxy system. I believe I found, with this design, a good compromise between creature comfort and efficient sailing behavior. Through the low silhouette of the boat, she will also sail well when reefed down. With a draft of only 0,4 m (rudders up) the boat can enter harbours and coves a lot of boats with the same length can not enter. But the boat will go to windward like any good mono hull.

This is our smallest offshore cruiser. A seaworthy fast cruising catamaran for a family of four. The performance of this boat will be exceptional on all courses to the wind. To make sure of this, the boat is light and has a low streamlined profile for windward performance. The study plans include diagrams for speed prediction and dynamic stability, so you can see for yourself.

The hulls have the proven trapezoid cross section of the PELICAN . For windward performance the boat has anti-vortex panels. These work a lot better as low aspect ratio keels and are not as prone to damage as boards. Besides, why spoil one of the best advantages of a multihull, low draft, to enter coves etc a keel boat never can enter? For an explanation how these work go to this article .

The boat is, like all our boats, of (ply)wood/glass/epoxy composite construction. Any handy amateur can build this boat without difficulties or surprises. Construction time will be around 1200 hours.

Designing a catamaran in this size is a challenge if you don't want to end up with a floating caravan.

I used our practical experience with our Pelican to design this boat. The maximum height in the central cabin is 1.48 m. I found the solution for reasonable ergonomics by using 3 entrances. To step in the hulls, the port or starboard entrance is used. The central entrance is very convenient to step in the central seating area. As shown in the drawing below, there is ample seat height in the central cabin. There is standing height (1,95m) in the hulls.

The trapezoid shaped hulls have a fine entrance. The length to beam ratio of the hulls is 1:11. This will guarantee a fast boat.

The boat is relatively low with good aerodynamic properties. Even with shortened sails the boat will go to windward. A factor often forgotten. There is sufficient room for four persons for extended voyages.

CONSTRUCTION

The boat is designed in a way that even first time boat builders can build the boat without difficulties. All 32 CAD drawings are to a scale of (1:1). A 32 page description will aid you building the boat. All our 26 years of experience designing boats for amateurs is flowing into this design. We chose again plywood as basic material for availability world wide and cost efficiency.

1 - floor 2 - bridge deck stringer 3 - door 4 - chard table /navigation 5 - book/instruments shelf’s 6 - deck stringers 7 - hatch 450x380 mm 8 - vertical mast bulkhead 12 mm plywood 9 - lockers 10 - two persons bunk 11 - pantry 12 - U settee for up to 6

Plans are delivered as E-book, 32 pages description and 32 1:1 CAD drawings - $320

Study plans consist of 16 pages and include 10 pictures, a short construction description table of contents of the plans and the list of materials - available for $15

https://www.ikarus342000.com/P86page2.htm

Blue Coast 105 Sailing Catamaran

The super yacht catamaran yacht BLUE COAST 105 " Allures " with a timeless elegant design by Jean-Jacques Coste for a sophisticated, fast performance luxury full-custom catamaran.

Description

This BLUE COAST 105 combines luxurious comfort on board with seaworthiness and life at sea with its tremendous performance under sail with 729sqm total sail area and engines of 2 x 440 Ps.

With long waterlines and a very efficient sail plan, the BLUE COAST 105 can reach speeds of over 20 knots in complete safety and comfort. Even under power, the top speed of 16 knots allows fast cruising to the destination.

The large interior volume allows the saloon deck and cabins to be freely arranged according to the owner's wishes.

The flybridge is a very comfortable outdoor area. A whirlpool, large sunbathing areas, a dinner table for 10 people and the wet bar with grill offer plenty of comfort. Forward on both sides a steering position and the winches for sail handling.

On the main deck, in the forward area, a dinner table for 10 people and a lounge area with 180-degree views of the sea, the bay or the marina. In the middle area of the main deck, another very spacious lounge and bar.

To starboard, a luxurious owner's suite with private luxury bathroom with double vanity and whirlpool bath, accessed via stairs.

The spacious aft cockpit is connected to the saloon by a wide-opening sliding door, creating an enormously large open space. Here too, a dinner table for 10 guests and two lounge sofas. The main deck and flybridge are the best places to relax and enjoy with friends and family.

On the lower deck to starboard 2 spacious VIP cabins with en suite facilities and forward crew quarters.  To port is the professional kitchen, where the chef's creativity knows no bounds. In front of it, two more luxurious double cabins and another crew quarter in front.

The interior can be designed according to your style.

The bow tips can be designed as a negative stem to extend the waterline and allow for wave piercing: When waves come from the front, the catamaran is not lifted, it does not lean and therefore does not lose speed.

Available with traditional diesel engines or with the innovative electric hybrid system "Green ECO Power" with electric motors.

Design according to your preferences

Alternatively, the design of this BLUE COAST 105 can be customised to your requirements in terms of number and layout of cabins, interior fittings and furnishings.

Manufacturing your Yacht

Under the constant supervision of Catamaris ®  and Jean-Jacques Coste, your BLUE COAST 105 catamaran will be built in a certified shipyard in Europe with many years of experience in successfully manufacturing numerous luxury yachts and multihulls.

Technical Specifications

Layouts of blue coast 105.

Every BLUE COAST YACHTS catamaran is unique and among the best full-custom catamarans in the market because of their creative designs and highest build quality. Jean-Jacques Coste's signature has made his designs timeless and elegant while maximising performance, comfort and luxury.

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KD 650 Plans

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Description

Additional information.

The KD 650 is an other approach for an affordable trailer catamaran for amateur construction. The boat is designed for coastal sailing and will have a good turn of speed with its efficient Gunter rig.

The boat is easy to build with plywood/glass/Epoxy construction. The first time DIY boat builder will have no problem building the boat. With the asymmetrical hulls, no dagger boards are necessary to go as well to windward as any very good mono hull.

To avoid the high costs for the rig, i.e. mast and rigging, the boat sports a modified Gunter rig. I "modernized" the rig so that only one halyard is necessary. The yard is fixed to the mast. The mast is free rotating. The result a semi wing sail. The plan shows how to build the mast from an Aluminum tube and some hardware. The gaff is made from clear fir, UD- carbon and glass cloth.

This Gunter rigged boat is a J class boat from Germany. This class is very old but still active. The Gunter rig main sail resembles a wing.

The beams are made from readily available Aluminum tubes. Besides cutting them to length, there is nothing to do. This will shorten the construction time by about 40% compared to boats where wooden beams have to be built.

The set up time, once at your favored sailing ground, is short. To make sure of this, I designed a quick beam fastening system. Only four nuts have to be fastened to fix the beams. The mast is only 4.3 m long and weights a mere 9 kg. Setting up the boat will take 2 people no more than an hour. This will be no different on a beach or in a port.

This picture is from a customer in Poland The boat is almost ready to go.

MAIN FEATURES

• Modern Gunter rig. Easy to build by your self and very efficient.
• The beams are fastened with a unique quick fastening system and four nuts. Easy to transport on a trailer.
• Trailing width 2m.
• The weight of a hull will be under 90 kgs.
• In each hull is enough space to sleep 2 persons.
• In one of the hulls there is space for a toilet.
• Good height for comfortable sitting.
• A small pantry can be added.
• The hulls are a-symmetrical to avoid dagger boards.
• The a-symmetry is 1/3 to 2/3.
• For easy of construction AL. tubes for the beams are used.
• Construction is ply wood/glass/Epoxy composite.
• Construction time will be around 500 hours

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