Design and Construction
Phil Southwell laid out a hull with a displacement of roughly 15,200 pounds — substantial for a 36-foot catamaran, and a figure that points toward volume and load-carrying rather than raw speed. The design is genuinely spacious, with beam used to create interior volume that gives liveaboards and extended cruisers real breathing room. The capsize ratio of 3.57 and a comfort ratio just over 10 reflect a boat that was engineered for offshore practicality rather than racing measurement rules. Twin keels keep the draft manageable, an asset in shallow anchorages and when hauling the boat. The displacement-to-length ratio of nearly 149 confirms this is a moderate to heavy-displacement catamaran — one that will carry provisions, cruising gear, and passengers without complaint, though it will not win any passage-making speed records against lighter contemporaries.
Rig and Sailing Character
The sail area-to-displacement ratio of 23.66 sits in the middle of the cruising catamaran range, suggesting a boat that moves adequately in decent breeze without being overpowered or requiring reefing anxiety whenever conditions build. The Island Spirit 37 offers the cruising and sailing experience you expect from a boat of its era — dependable upwind and off-wind performance calibrated for passage-making rather than racing. The platform's mass works in its favor in a seaway, dampening the hobby-horsing that can make lighter production cats uncomfortable in short chop. Fortuna paired the hull with a Yanmar 30 hp diesel — a conservative power choice well matched to the displacement and adequate for marina maneuvering, inlet transits, and light-air motoring passages.
Accommodations
Interior volume is where the Island Spirit 37 makes its strongest argument. The wide beam translates into real saloon and cabin space, and the twin-hull layout gives the interior a natural separation between living and sleeping areas. The design includes the creature comforts a cruising couple or family would want, and many examples have been upgraded over the years with solar, watermakers, and modern electronics as technology evolved.
Known Considerations
A boat designed around simplicity will have straightforward systems, and that is largely a virtue for the owner who handles most maintenance themselves. The Yanmar engine is among the most widely supported marine diesels, making parts and service accessible in most cruising grounds. The conservative sail plan means that in light air — under about eight knots true — the Island Spirit 37 will need its iron sail, as it lacks the power-to-weight ratio of a lighter performance cat to ghost along in marginal conditions. The heavy displacement also means that overloading, a chronic problem on liveaboard cats, degrades performance more noticeably than on a lighter platform. Owners intending to carry the full complement of cruising gear, dinghy, outboard, dive equipment, and provisions will want to be disciplined about weight management.
Refit and Ownership
A production run ending in 2005 means the youngest examples are now well into their second decade, and buyers should expect to budget for systems refreshes appropriate to the age of any given boat. The straightforward construction and conventional layout work in an owner's favor at refit time: systems are not exotic, and the wide beam makes working inside both hulls less contorted than on narrower monohulls.
The Verdict
The Island Spirit 37 is a boat that delivers honestly on a clear promise: a spacious, practical, and straightforward cruising catamaran for sailors who want to go places rather than impress onlookers. Phil Southwell's design by way of Fortuna Catamaran prioritized real-world usability — volume, load-carrying, manageable systems — over the light-air performance numbers that dominate modern catamaran marketing. For a couple or small family looking for an affordable entry into bluewater-capable catamaran cruising, it remains a credible platform.
Pros
- Genuine interior volume for its length, suited to extended liveaboard use
- Simple, conventional systems that are easy to maintain and service globally
- Conservative displacement and Yanmar diesel support reliable long-range passages
- Phil Southwell's design brief favors practical cruising utility over complexity
Cons
- Heavy displacement limits light-air sailing performance; motoring in calm conditions is common
- Capsize and comfort ratios reflect a cruiser, not a performer — not a boat for sailors chasing passage speed
- Production ended 2005; all examples require age-appropriate systems budgeting at purchase
- Overloading degrades performance more noticeably than on lighter modern platforms
