In Brief

Gemini 105M Sail Plan

After a 2008 Pacific crossing, the owner of a Gemini exclaimed, “the catamaran hull performs flawlessly in open blue water as well as the light winds of the Kona coast … the forward stateroom is queen sized .. the main cabin seats six … plenty of height in the full head with shower.” Great sailing and lots of living space – what’s not to like?

The Gemini is the most popular cruising catamaran in the world with more than 1000 hulls manufactured over nearly 30 years. While most of those hulls are in service as coastal cruisers, many have crossed the oceans. In 2001 the owner, designer and builder of the Gemini catamaran series, Tony Smith, sailed a new Gemini 105Mc across the Atlantic Ocean for a delivery to Southampton, England topping out at 18 knots of speed (surfing down the face of heavy seas). Many more of these adventures are chronicled in the Gemini Gems magazine (print and electronic versions) or the very active Gemini Yahoo forum.

A large cockpit with wheel steering and plenty of room for an afternoon picnic greats the sailor ascending the aft stairs. A generous, hard foredeck is surrounded by a stainless pulpit for the entire bow and lifelines running along the somewhat narrow side decks. With only about 8000 pounds of displacement, anchor chain and rode need not be overly heavy. Sailing a boat with such light displacement across the ocean requires careful consideration of heeling angles and reefing. Anything above seven degrees of heel means it’s time to reduce sail.

Returning to the cockpit allows the sailor access to the interior. Starting at the same level as the cockpit sole, immediately one is greeted by a salon table that comfortably seats four and even eight in a squeeze. Descending a few steps to the left and moving forward is found the head and shower. Hot water is provided by a propane driven instant heater, like an RV or many European homes. The big advantage is that if you have water in the two 35 gallon fresh water tanks, then you can have hot water.

Gemini 105M Layout In the aft part of both hulls are two births. The master cabin is in the starboard hull forward, featuring a queen sized bed. There is a tremendous amount of storage for dry goods in the galley and a propane driven refrigerator (using the ammonia cycle instead of a compressor).

The Gemini is mainly driven by the roller furled genoa and somewhat small main, though many sailors add screechers, asymmetrical spinnakers and jibs to their sail lockers. Each hull has a cable driven, hand-cranked centerboard that can be completely tucked into a trunk in the hull, reducing the draft (assuming the rudders are likewise raised), or dropped three feet into the water, dramatically improving upwind performance. While most sailing and motoring can be accomplished with both boards let half-way down, the ability to adjust the boards to wind, current, sailing or anchoring conditions is one of the Gem’s great strengths.

The 105 and 105MC are driven by a 27 HP Westerbeke diesel engine driving a Sillette tilting saildrive. The saildrive is often a source of concern and maintenance is critical on the bellows.

History

There are three models of the Gemini, the classic (1981-1990), the 3200 and 3400 (1990-1996) and the most popular, the 105M and 105MC (1996-2012). This article focuses on the most popular model, 105M and 105MC, which differ only in details of the interior construction. The classic, 3200 and 3400 were all manufactured in Annapolis, Maryland. Recently, Performance Cruising has partnered with Hunter Marine to manufacture the 105Mc in Alacua, Florida. There are nearly always pre-owned examples of all three types on the market.

The model most likely to be used in blue water is the 105M or 105MC discussed here. For this model, the hull lines were redrawn moving the maximum beam further aft to reduce wave drag. These new hulls have a 9:1 length:beam ratio. The new hulls also have a somewhat higher static stability. The newer hull design is stiffer, increasing seaworthiness for trans-ocean cruising.

The hull is solid GRP, laminated from woven roving and mat with isophthalic polyester resin. An outer layer of polyester resin and gel coat protects against osmosis. The decks and cockpit sole are GRP sandwich with balsa wood core.

Specifications

These specifications are for the 105M
LOA: 33′ 6″
Beam: 14′ 0″
LWL: 31′ 9″
Draft, Minimum: 1′ 6″
Draft, Maximum: 5′ 6″
Displacement: 8600 lbs.
Bridge Clearance: 46′ 0″

Engines: 1, 27 HP Westerbeke with Sillette saildrive

Water: 60 US Gal.
Fuel: 36 US Gal.
Holding: 18 US Gal.

Designer: Tony Smith
Builder: Performance Cruising
Year Introduced: 1982
Year Ended: still in production
Total Built: 1100+

Similar Boats

Gemini 3000
Gemini 3200
Gemini 3400
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Iroquois MK11
TomCat 9.7
EndeavourCat 36

Link, References, and Further Reading

» A review of the Gemini 105M by John Kretschmer, Sailing Magazine, Aug 1999
» Chesapeake Bay Magazine’s review of the Gemini 105Mc

Credits

Original article submitted by Robert Malkin.

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2 Responses to “Gemini 105M”

  1. Juan Carlos says:

    Interested in second hand sailing catamaran

  2. […] first time cat sailor BlueWaterBoats website just added a review of the Gemini 105m: The Gemini 105M Sailboat : Bluewaterboats.org __________________ Zen Again Catalina 25 #2818 Tide goes in, tide goes out. Never a […]

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