Design and Construction
The 105M’s defining structural choice is a one-piece molded hull and deck that together form a rigid bridgedeck, joined on a flange and through-bolted every four inches with a PVC rubbing strake masking the seam. Smith rejected cored hulls outright, building the hand-laid fiberglass hull solid for strength and simplicity, while shielding it with a barrier coat and vinylester resin against osmotic blistering. The deck alone is cored with half-inch end-grain balsa on horizontal surfaces. Below, the bridgedeck clearance tapers from 39 inches at the bow to 24 at the maststep and 15 under the helm before rising toward the engine, a profile that keeps the cabin volume high without a wider footprint. The boat’s length-to-beam ratio sits near 9 to 1, and the narrow hulls with retractable centerboards draw just 18 inches boards-up.
Rig and Handling
The 105M carries a double-spreader masthead rig with a 45-foot air draft, a long aft mainsheet traveler for end-boom sheeting, and genoa tracks running the cabintrunk. Two self-tailing winches sit at the aft end of the trunkhouse, halyards are led aft, and the standard main is slab-reefed rather than full-battened. Steering runs through Teleflex push-pull cables to a pair of kick-up rudders, with the wheel on the starboard bulkhead. Test sailors found her quick: under full main and a small genoa in 15 knots she zipped along at better than 8 knots, held 7.5 knots at 50 degrees apparent and 7 at 45, then reached 10 to 11 knots on a beam reach and touched 12 in a gust. She tacked easily and accelerated fast, though boat speed fell off sharply when pinned below 40 degrees. Smith claimed the hull shape all but eliminates a bow wave, aiding that efficiency. One handling caveat: the helmsman cannot reach the mainsheet or genoa winches from the wheel.
Accommodations
Smith laid out the 105M for a couple to live aboard, with berths for six when needed, centering the bright saloon on a U-shaped dinette and a stand-alone refrigerator that runs on propane under way because the hull never heels beyond 5 degrees. Gray-tinted Lexan saloon ports resist leaking and crazing, and the large aft windows slide open like household sash. The centerline master stateroom looks forward; the port hull holds the molded head-and-shower forward, a large nav station amidships, and a double cabin aft, while the starboard hull mirrors with a double aft and an amidships galley with a two-burner propane stove and double sinks. Two 30-gallon water tanks sit under each aft berth. Molded cabin soles carry teak-and-holly inserts, hulls are foam-backed vinyl, and the headliner mixes molded glass with foam fabric. Side decks are narrow by necessity, and the cockpit wears a hard dodger stretching more than four feet aft with molded swim steps on each hull.
Known Issues
The only operational shortfall from sea trials is the helmsman’s inability to reach the sheet winches from the steering position, meaning crew must handle trim from the trunkhouse rather than the wheel.
The Verdict
The Gemini 105M is a thoughtful cruiser’s catamaran: narrow enough to berth cheaply yet stable and quick, built solid where it counts and laid out for real liveaboard use. Its compromises are few and specific.
Pros
- Fits conventional marina slips at 14-foot beam and 18-inch boards-up draft
- Solid hand-laid hull with blister-resistant resin system
- 15-percent stability gain from redesigned hull without beam penalty
- Lively performance: 8+ knots upwind, double digits reaching
- Propane reefer viable due to minimal heel
Cons
- Helmsman cannot reach sheet winches from wheel
- Poor close-winded speed below 40 degrees apparent
- Narrow side decks limit working room
