The Westerly Typhoon 37 Sailboat
Specs & Key Performance Indicators

The Westerly Typhoon 37, an aft-cockpit fractional sloop, was designed by Ed Dubois and built in the UK by Westerly Marine Construction Co Ltd.

A Westerly Typhoon 37

Published Specification for the Westerly Typhoon 37

Underwater Profile: Fin keel & spade rudder

Hull Material: GRP (Fibreglass)

Length Overall: 37'4" (11.4m)

Waterline Length: 31'11" (9.7m)

Beam: 12'4" (3.8m)

Draft: 6'0" (1.8m)

Rig Type: Fractional sloop

Displacement: 16,470lb (7,471kg)

Designer: Ed Dubois

Builder: Westerly Marine Construction Co Ltd (UK)

Year First Built: 1990

Year Last Built: 1993

Number Built: 40

Published Design Ratios for the Westerly Typhoon 37

1. Sail Area/Displacement Ratio: 21.3

Less than 16 would be considered under-powered;
16 to 20 would indicate reasonably good performance;
Over 20 suggests relatively high performance.

2. Ballast/Displacement Ratio: 36.7

Under 40: less stiff, less powerful
Over 40: stiffer, more powerful

3. Displacement/Length Ratio: 226

Under 100: Ultralight
100 to 200: Light
200 to 275: Moderate
275 to 350: Heavy
Over 350: Ultraheavy

4. Comfort Ratio: 26.7

Under 20 indicates a lightweight racing boat
20 to 30 indicates a coastal cruiser
30 to 40 indicates a moderate offshore cruising boat
40 to 50 indicates a heavy offshore boat
Over 50 indicates an extremely heavy offshore boat

5. Capsize Screening Formula: 1.9

Under 2.0 (the lower the better): Better suited for ocean passages
Over 2.0: Less suited for ocean passages

Summary Analysis of the Design Ratios for the Westerly Typhoon 37

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1. A Sail Area/Displacement Ratio of 21.3 suggests that, in the right hands, the Westerly Typhoon 37 will have enough performance to leave most other sailboats of similar waterline length well astern.

2. A Ballast/Displacement Ratio of 36.7 means that a sailboat like the Westerly Typhoon 37 (which doesn't have a stiffness-enhancing bulb keel), is likely to benefit from being reefed early to keep her sailing upright in a moderate breeze.

3. A Displacement/Length Ratio of 226 tells us the Westerly Typhoon 37 is a moderate displacement cruiser, which means she'll carry all your cruising gear without it having a dramatic effect on her performance. Most of today's sailboats intended for offshore cruising fall into this displacement category.

4. Ted Brewer's Comfort Ratio of 26.7 suggests that crew comfort of a Westerly Typhoon 37 in a seaway is similar to what you would associate with the motion of a coastal cruiser with moderate stability, which is not encouraging news for anyone prone to seasickness.

5. The Capsize Screening Formula (CSF) of 1.9 indicates that a Westerly Typhoon 37 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0.