BoatsThai MK IV

Thai MK IV

Catamaran, twin centreboards · Frac. Sloop (Rotating Spar) · First built 1958

A Rod Macalpine-Downie designed catamaran featuring a rotating spar and an ultra-light displacement for high-speed racing

Designed by Rod Macalpine-Downie, built by Sailcraft.

LOA
Beam
Draft (max)
Displacement
Hull type
Catamaran Twin Cbrd.

The record

Full specifications

The complete reference set — tap any figure to switch between metric and imperial.

Dimensions
Weights
Rig & sail area
Rig
Frac. Sloop (Rotating Spar)
Ratios
SA / displacement
88.8
Hull
Hull type
Catamaran Twin Cbrd.
Construction
Wood
Production
Years built
First built 1958
Designer
Rod Macalpine-Downie
Builder
Sailcraft

Boats like this, on the water

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Supercat 154.65 mSame hull family0.5 m shorterA high-performance beach catamaran with a rotating spar and an exceptional sail-area-to-displacement ratio
Why St. John Feels Nothing Like St. Thomas E38116:38from Wildly Intrepid Sailing
Hobie 165.05 mSame hull familyNear-identical lengthThe most popular sailing catamaran ever built, featuring a rotating spar and boardless hull for high-speed beach sailing
Hobie Cat 16 Sailing - 5 days & 400kmfrom Igor Stropnik
Hobie FX One5.18 mSame hull familyNear-identical lengthA 5.18-meter single-handed catamaran featuring a rotating fractional rig and an exceptional 56.56 sail area-to-displacement ratio
Hobie Cat, 15 days & 1200km2:47from Igor Stropnik
Hobie Tiger 185.51 mSame hull family0.3 m longerDesigned to the Formula 18 rule, this 5.5-meter catamaran features twin daggerboards and a high power-to-weight ratio
4 day solo passage to the Greek town of Vasiliki 🇬🇷 & sailing cats with ​⁠@JOYRIDER TV26:10from Sam Holmes Sailing

The family

Related models

The designs closest to hers — usually the rest of the builder's range, sometimes the same hull sold under another name.

Paper TigerA Ron Given-designed catamaran with a rotating cat rig, built for amateur plywood construction and still actively racedMaricat 4.3A versatile Australian beach catamaran with a long production run and three distinct racing classes for all skill levelsTiger CatThe first one-design catamaran class in the US, derived from the 1959 One of a Kind Regatta-winning prototypeThom Cat 15A Menger-designed gaff-rigged daysailer with a high sail-area-to-displacement ratio for spirited performanceTopcat K4XA 115kg catamaran with a rotating fractional rig, available in Active or Touring versions with flat-top sail optionsTaipan 4.9A lightweight 4.95-metre catamaran with a rotating fractional rig that remains competitive in Formula 18 racing

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