The Gunfleet 58 Sailboat
Specs & Key Performance Indicators

The Gunfleet 58, a centre-cockpit sloop, was designed by Tony Castro and built in the UK by Gunfleet Marine Ltd.

'Andiamo', a Solent-rigged Gunfleet 58 Sloop at anchor in Falmouth Harbour, AntiguaThe Gunfleet 58

Published Specification for the Gunfleet 58

  • Underwater Configuration: Bulb keel with centreboard & twin spade rudders
  • Hull Material: GRP (Fibreglass)
  • Length Overall: 59'10" (18.3m)
  • Waterline Length: 53'8" (16.4m)
  • Beam: 17'1" (5.2m)
  • Draft: 11'10" (3.6m) centreboard down, 5'9" (1.7m) centreboard up
  • Rig Type: Masthead Sloop with Solent Rig
  • Displacement: 68,343lb (31,000kg)
  • Designer: Tony Castro
  • Builder: Gunfleet Marine (UK)
  • Year First Built: 2013

Published Design Ratios for the Gunfleet 58

1. Sail Area/Displacement Ratio: 18.1

  • 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: 30.3

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

3. Displacement/Length Ratio: 197

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

4. Comfort Ratio: 43.5

  • 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 Gunfleet 58

1. A Sail Area/Displacement Ratio of 18.1 suggests that the Gunfleet 58 will, in the right conditions, approach her maximum hull speed readily and satisfy the sailing performance expectations of most cruising sailors.

2. A Ballast/Displacement Ratio of 30.3 would usually mean that the Gunfleet 58 would have a tendency to heel uncomfortably in a gust, and need to be reefed early to keep her sailing upright in a moderate breeze.

However, as she has much of her ballast in a bulb at the foot of her keel, she's likely to be considerably stiffer than her published Ballast/Displacement Ratio might suggest.

3. A Displacement/Length Ratio of 197, tells us the Gunfleet 58 is a light-to-moderate displacement sailboat. If she's loaded with too much heavy cruising gear her performance will suffer to a degree.

4. Ted Brewer's Comfort Ratio of 43.5 suggests that crew comfort of a Gunfleet 58 in a seaway is similar to what you would associate with the motion of a heavy bluewater cruising boat. Pitching and rolling will be well damped - your cup of coffee on the salon table stands a reasonable chance of staying there in most conditions.

5. The Capsize Screening Formula (CSF) of 1.7 tells us that a Gunfleet 58 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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