Crowther Twiggy 31 Information, Review, Specs

Sailing Performance & Handling

The Twiggy 31 is defined by its exceptional power-to-weight ratio. With a displacement that often hovers around 1,500 to 2,000 kg depending on the build material, the boat achieves a Sail Area/Displacement ratio that rivals modern racing yachts. On the water, this translates to a vessel that is exceptionally sensitive to light airs but capable of sustained speeds exceeding 20 knots in the right conditions.

Handling is characterized by the boat's "needle-like" main hull and high-buoyancy floats (amas). Unlike modern wide-beamed cruising trimarans that rely on massive initial stability, the Twiggy 31 requires active sail trimming. Editorial archives from Multihulls World highlight the design's transition from early Crowther "V" hulls to more rounded, sophisticated sections that improved sea-kindliness in offshore chop. However, the boat is known for a relatively wet ride; the low freeboard and narrow beams mean that spray is a constant companion at high speeds. Tracking is generally excellent due to a deep daggerboard, though the boat can feel "flighty" if the rig is not depowered appropriately as the wind builds.

Interior Comfort & Variations

Living aboard a Twiggy 31 is often described as "sophisticated camping." Because the main hull is extremely narrow to minimize drag, the interior volume is severely restricted. The cabin typically features a minimalist galley and two longitudinal settee berths in the main saloon, with an additional "pipe cot" or small V-berth forward. Headroom is limited, usually requiring a "crouch-walk" for most adults, though some versions featured a "pop-top" or a slightly raised coachroof to alleviate this.

There are two primary variations of the design: the original Mk I and the subsequent Mk II. The Mk II version featured slightly more volume in the floats and refined hull lines to improve load-carrying capacity, though the interior remained largely Spartan. Some custom builds utilized the "Spindrift" style of cabin, which offered a slightly wider "winged" deck area to increase internal floor space, but these are rare. Materials range from marine-grade plywood (common in early home-built examples) to sophisticated foam-core composites, which significantly impact the interior finish and aesthetic.

Popular Mentions & Media

The Twiggy 31 gained international fame through the exploits of Lock Crowther himself and several high-profile racers. The prototype, Twiggy, was a standout performer in the 1978 Round Britain Race and the OSTAR, proving that a 31-foot multihull could reliably cross oceans at speeds that left much larger monohulls behind. The design is frequently cited in historical retrospectives of the "Crowther Design" legacy at the Australian National Maritime Museum, which holds many of the designer's original plans and serves as a primary repository for his contribution to naval architecture.

Known Issues & Buyer’s Checklist

Prospective buyers must approach the Twiggy 31 with a focus on structural integrity, as many were amateur-built from plans.

• Beam Connections (Akas): The critical stress points where the beams join the hulls must be inspected for stress cracking or "working." In plywood models, these joints are susceptible to rot if the fiberglass sheathing has been compromised.
• Core Integrity: For foam-sandwich builds, delamination is a significant concern, especially in areas of high slamming loads under the bows. A moisture meter and percussion "tap" test are essential.
• Daggerboard Trunk: The trunk is a common site for leaks and structural fatigue. Ensure the trunk is reinforced and that there is no evidence of "weeping" where it meets the hull.
• Rigging Loads: Because the Twiggy 31 is a high-performance boat, the chainplates and mast step undergo immense loads. Inspect for any deformation in the deck or bulkheads around these areas.

Community & Resources

The legacy of the Twiggy 31 is maintained by a dedicated community of multihull enthusiasts. Technical data and historical discussions are most frequently found through the Multihull Yacht Club Queensland (MYCQ) and the Australian Multihull Series, organizations that Lock Crowther was intimately involved with. Owners also tend to congregate in specialized multihull technical groups, sharing modifications for modernizing the rig or converting the boat for "fast cruising."

The Verdict

The Crowther Twiggy 31 is a "sailor’s sailboat," designed for those who prioritize the thrill of speed and the elegance of classic multihull design over the comforts of a floating apartment.

Pros:

• Exceptional speed and light-air performance.
• Proven offshore pedigree with several successful ocean crossings.
• Beautiful, iconic aesthetic that remains a "head-turner" in any marina.

Cons:

• Extremely cramped interior with limited headroom and storage.
• Requires a high level of sailing skill and attention in heavy weather.
• Construction quality varies wildly due to the prevalence of home-built examples.