The Trapper 501 Sailboat

The Trapper 501, a masthead sloop, was designed by Rob Ball and built in the UK by Trapper Yachts Ltd. 

A Trapper 501 sailing in the River Tamar in Devon, UKA Trapper 501 sailing in the River Tamar, Devon, UK

Both the Trapper 500 and the 501 were based on the C&C 37. The 501 differed from the 500 by a different coach roof and interior mouldings

Published Specification for the Trapper 501

Underwater Configuration:  Fin with spade rudder

Hull Material:  GRP (fibreglass)

Length Overall: 27' 4" / 8.33m

Waterline Length: 22' 2" / 6.76m

Beam: 9' 2" / 2.80m

Draft: 4' 3" / 1.30m

Rig Type: Masthead Sloop

Displacement: 5,180lb / 2,350kg

Designer: Rob Ball (Camper & Nicholson)

Builder: Trapper Yachts Ltd (UK)

Year First Built: 1977

Year Last Built: 1987

Number Built: 600

Owners Association: Trapper Owners Association

Published Design Ratios for the Trapper 501

1. Sail Area/Displacement Ratio: 18.4

  • 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: 48.5

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

3. Displacement/Length Ratio: 212

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

4. Comfort Ratio: 17.6

  • 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: 2.1

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

read more about these all-revealing numbers...

Summary Analysis of Published Design Ratios for the Trapper 501

A Sail Area/Displacement Ratio of 18.4 suggests that she'll approach her maximum hull speed readily and satisfy the sailing performance expectations of most cruising sailors.

A Ballast/Displacement Ratio of 48.5 means that she'll stand up well to her canvas in a blow, enabling her to power through the waves.

A Displacement/Length Ratio of 212, tells us she's 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.

Ted Brewer's Comfort Ratio of 17.6 suggests that crew comfort in a seaway is similar to what you would associate with the motion of a lightweight racing boat. Upwind she'll slam enough to shake your fillings out with a motion that cruising sailors have no desire to get used to.

Her Capsize Screening Formula of 2.1 tells us that she would not be a good choice of sailboat for ocean passage-making.


Sailboats in the Trapper range include:

  • Trapper 28
  • Trapper 300
  • Trapper 400
  • Trapper 42
  • Trapper 500/501
  • Trapper 950
  • Trapper T250
  • Trapper T250s
  • Trapper TS240

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