The Biscay 36 Sailboat
Specs & Key Performance Indicators

The Biscay 36, a heavy displacement aft-cockpit cruising yacht, was designed by Alan Hill and built in the UK by Robert Ives Ltd together with Falmouth Boat Construction Ltd.

A Biscay 36 sailboat at anchorA Biscay 36

Published Specification for the Biscay 36

Underwater Profile: Long keel

Hull Material: GRP (Fibreglass)

Length Overall: 35'11" (11.0m)

Waterline Length: 27'0" (8.2m)

Beam: 10'9" (3.3m)

Draft: 5'9" (1.8m)

Rig Type: Masthead sloop*

Displacement: 15,680lb (7,112kg)

Designer: Alan Hill

Builder: Robert Ives Ltd together with Falmouth Boat Construction Ltd. (UK)**

Year First Built: 1974

Number Built: 29

* Also available as a ketch

** Robert Ives Ltd created the deck & hull mouldings, fitting out and completion by Falmouth Boat Construction Ltd.


Published Design Ratios for the Biscay 36

1. Sail Area/Displacement Ratio: 14.6

  • 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: 42.2

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

3. Displacement/Length Ratio: 356

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

4. Comfort Ratio: 34.3

  • 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: 1.7

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

read more about these Key Performance Indicators...


Summary Analysis of the Design Ratios for the Biscay 36

1. A Sail Area/Displacement Ratio of just 14.6 suggests that the Biscay 36 will need a stiff breeze to get her going. In light conditions, unless you've got plenty of time on your hands, motor-sailing may be the way to go.

2. A Ballast/Displacement Ratio of 42.2 means that a sailboat like the Biscay 36 (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 356, tells us the Biscay 36 creeps into the ultra-heavy displacement category. Load her up as much as you like and her performance will be hardly affected, not that it was ever startling. Few if any sailboats are built to this displacement category these days - but they remain popular with some long-distance sailors.

4. Ted Brewer's Comfort Ratio of 34.3 suggests that crew comfort of a Biscay 36 in a seaway is similar to what you would associate with the motion of a moderate bluewater cruising boat - a predictable and acceptable motion for most seasoned sailors.

5. The Capsize Screening Formula (CSF) of 1.7 indicates that a Biscay 36 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0. 


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