Catamaran

Overview

A cruising sailing catamaran carries its accommodation on a bridgedeck that spans two slender hulls. Wind in the sails is the main driver, and a pair of small auxiliary diesels handle harbours and calms. The wide stance between the hulls resists heeling, so the boat sails close to upright and stays level at anchor, and the fine waterline of each hull keeps drag low. Draft is shallow because there is no deep ballast keel, which lets the boat reach anchorages a monohull of the same length cannot.

The two Demi-Hull mouldings are tied together by the Bridgedeck & Nacelle, which carries the saloon, the forward trampoline and the mast step. Drive comes from the Rig and Sail Wardrobe, trimmed through the Running Rigging & Deck Hardware. A Saildrive Unit in each hull provides auxiliary power, the Steering links twin rudders to two wheels, and the Electrical System, Navigation Electronics and Accommodation systems make the boat able to cruise for weeks off the grid.

Hulls and bridgedeck

Each demi-hull is a foam-cored GRP laminate, light and stiff, subdivided by bonded watertight bulkheads so that damage to one compartment cannot sink the boat. Longitudinal stringers stiffen the shell against rig and slamming loads. A lifting daggerboard in each hull drops below the canoe body to resist leeway when sailing upwind, then retracts into its case for shallow water and downwind legs, which is why the quoted draft is taken with the boards up.

The bridgedeck nacelle sets the saloon sole well above the water so that waves pass under the boat instead of pounding the underwing. An aluminium forebeam ties the two bows together and anchors the forestay, and the mesh trampoline forward of it lets crew work the anchor and bow while spilling green water. The saloon glazing is bonded tempered glass, and the coachroof carries the hardtop and the solar mounts.

Rig and sails

The boat carries a fractional aluminium Mast stepped on the coachroof, stayed by a forestay, cap shrouds led over two pairs of swept spreaders, and diagonal stays, all tensioned through turnbuckles into bonded chainplates. Sweeping the spreaders aft lets the rig stand without a backstay, which leaves room for a large square-top mainsail. The mainsail is fully battened with full-length battens holding its roach, and it drops into a lazy bag on the boom.

The working headsail is a self-tacking jib on a curved track, so the crew can tack without handling sheets. For light airs a furling gennaker sets from the bow on a removable bowsprit. The jib rolls away on a foil-and-drum Jib Furler turning around the forestay, which lets the crew reduce headsail area from the cockpit.

Deck hardware

Lines lead aft from the mast through rope clutches to four self-tailing winches at the helm stations, so sails can be trimmed and reefed without leaving the wheel. The mainsheet runs as a multi-part purchase to a traveller car on an athwartships track, which sets both mainsail angle and twist. Halyards, blocks and cam cleats route the running rigging, and an electric windlass on the forebeam handles the bow anchor and chain.

Propulsion

Each hull has an auxiliary diesel on a saildrive leg ending in a folding propeller that closes up under sail to cut drag. The legs pass through the hull on a rubber diaphragm seal. Splitting drive between the hulls lets the helm turn the boat within its own length by running one engine ahead and the other astern, useful in tight marinas where a single-screw boat would need spring lines. The diesels also drive the alternators that charge the house bank.

Systems

A lithium iron phosphate house bank feeds an inverter/charger for domestic AC and is topped up by the engine alternators, by a coachroof solar array through an MPPT controller, and by shore power. A battery monitor tracks state of charge. The navigation suite puts wind, depth and speed instruments, a chartplotter, an autopilot and a VHF with AIS on one network, and the autopilot drives a ram on the rudder tie bar to hold a course offshore.

Accommodation

Cabins sit down in the hulls, clear of the saloon, with double berths and standing headroom. The galley is at saloon level beside the cockpit so the cook stays with the crew, and a head with a holding tank is fitted in each hull. Fresh water and diesel are split between the hulls to keep the boat in trim.