LISO 39′ Alloy Cruising Cutter – Design # 043


One of our more recent designs is this elegant, fast cruising cutter, intended for offshore passagemaking by a lifelong sailor planning his second single-handed circumnavigation. Primary objectives were higher average speed, more interior space, less maintenance and greater structural integrity than the 32′ GRP cutter in which he had previously cruised. Specific design constraints included the need for a furling mainsail, a cutter rig, a draft no greater than 5’6″ and a permanent (hard) dodger with removeable side and front windows. Apart from these issues we were given free reign to produce a boat according to our own taste. I believe this to be a good-looking boat which will turn heads despite the purposeful appearance of the unpainted aluminium topsides. There is a nice spring to the sheer which always looks graceful and balances the largish coachroof (average headroom is 6′ 3″ throughout as the client is definitely not “vertically challenged”). The overhangs are moderate, resulting in a longish waterline, in keeping with the need to ensure decent average daily runs.

The hull shape is a modified radius chine. Looking at the body plan one would assume this to be a round bilged hull. We have taken extreme care to avoid the usual flat spots in the topside and bottom panels by introducing a slight amount of transverse camber and as a result the tangency with the radius chine panel is unnoticeable. The hull lines are nicely balanced partly due to not needing extreme beam for unrealistic accommodation volume requirements. I believe she will drive easily through the water and with a waterline length of almost 35 feet average daily runs of over 150 nautical miles will be achievable.

Construction is of marine grade aluminium alloy, either 5083 H116 or 5086 H112. The scantlings specified are well in excess of the requirements of the various classification societies so this boat will quite adequately stand up to the rigours of offshore voyaging. As previously mentioned she will be unpainted above the waterline completing the low maintenance requirement. A full set of CNC cutfiles and assembly drawings have resulted in an efficient and high quality fabrication of the metal structure. The attached pictures bear testimony to this.

The spacious interior contains no real surprises and what is not really evident is the elbowroom all round. All berths are over 2050mm (6′ 8″) in length. With such a small crew there is no need to fit a second head into the boat. Neither is a second quarterberth needed to port, aft of the galley. Instead we have a large lazarrette which is accessible from the port cockpit seat. It is our intention, however, to develop an alternative layout for the boat which could suit a larger crew. On shorter cruises.

The cockpit is one area which reflects some of the owner’s previous experience as well as his intention to sail shorthanded. All lines lead aft to the winches on top of the coachroof, within the hard dodger. All sails are furling, including the main which furls in the Selden mast (F265 section). At the aft end of the cockpit is a pedestal on centreline which serves at least 3 functions ie. housing the twin (20 lb) propane cylinders and a stern anchor/rode. In addition the WindPilot “Pacific” self-steering vane is mounted on the aft face. The rudder stock emerges from the top of this pedestal bringing the tiller to a comfortable level. Alongside this pedestal are twin walkthrough passages to the boarding platform. The intention is to fit very stout washboards in these openings to prevent boarding waves from inundating the cockpit. Those with a keen eye will have noted that the cockpit seats are too short for sleeping outdoors in tropical anchorages! This is not an oversight as we have planned for one or both of the transom “washboards” to be deployed in dedicated channels to extend the seats to a similar length as the berths inside the cabin. Notice also the deck storage lockers housing the liferaft to port and sundries (jerrycans etc.) to starboard.
Overall this is a conservative, no-nonsense, rugged and seaworthy cruising boat which, in my opinion, can be sailed to almost anywhere after which she will then be ready to go again!

LOA 11.92m (39’ 1.5”)
LOD 11.75m (38’ 6.5”)
DWL 10.56m (34’ 8”)
Beam 3.75m (12’ 3.5”)
Draught 1.675m (5’ 6”)
Sail Area 68.4 m² (736 sq. feet)
Wetted Surface 29.8 m² (320.9 sq. feet)
Power Yanmar 3JH3E (40hp)
Displacement 9100 kg (20 062 lbs)
Ballast 3120 kg (6878 lbs)
Immersion Rate 235 kg/cm (1314 lbs/inch)
Fuel Capacity 285 litres (75 U.S. Gallons)
Water Capacity 265 litres (70 U.S. Gallons)
Dynamic Stability Factor 74 (40 = lower limit recommended for ocean voyaging)
Prismatic Coefficient 0.56
Displacement/Length Ratio 215
Sail Area/Displacement Ratio 16
Sail Area/Wetted Surface Area Ratio 2.29