The Seadog 30 Sailboat

The Seadog 30, a heavy displacement ketch, was designed by Reg Freeman and built in UK by Reg Freeman Yachts Ltd.

'Wagtail', a Seadog 30 Ketch, at anchor in the mangroves at English Harbour, Antigua'Wagtail', a Seadog 30 Ketch, at anchor in the mangroves at English Harbour, Antigua

Published Specification for the Seadog 30

Underwater Profile: Triple keel

Hull Material: GRP

Length Overall: 30'0" / 9.14m

Waterline Length: 24'0" / 7.32m

Beam: 9'6" / 2.9m

Draft: 3'6"/ 1.1m

Rig Type: Ketch

Displacement: 12,880lb / 5,842kg

Designer: Reg Freeman

Builder: Reg Freeman Yachts (UK)

Year First Built: 1966

Year Last Built: 1974

Number Built: 130

Owners Association: SeaDog Owners Association


Published Design Ratios for the Seadog 30

1. Sail Area/Displacement Ratio: 14.9

  • 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: 30.4

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

3. Displacement/Length Ratio: 416

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

4. Comfort Ratio: 38.5

  • 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: 1.6

  • 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 the Design Ratios for the Seadog 30

1. A Sail Area/Displacement Ratio of just 14.9 suggests that the Seadog 30 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 30.4 means that unless the bulk of the ballast is concentrated in a bulb at the foot of her keel, the Seadog 30 will have a tendency to heel excessively in a gust, and she'll need to be reefed early to keep her sailing upright in a moderate breeze. 

3. A Displacement/Length Ratio of 416, tells us the Seadog 30 is firmly in 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 38.5 suggests that crew comfort of a Seadog 30 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 1.6 tells us that a Seadog 30 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0. 

Recent Articles

  1. A Van de Stadt Caribbean 40 Sailboat for Sale

    Jul 04, 22 10:29 AM

    'Stormalong', a steel-hulled go-anywhere Van de Stadt Caribbean 40 sailboat is for sale

    Read More

  2. The Tartan 34 Sailboat

    Jul 01, 22 03:18 AM

    Interested in the Tartan 34 sailboat? Here are the pics, specs and performance predictions you're looking for...

    Read More

  3. A Tartan 34C for Sale

    Jun 29, 22 02:45 PM

    'Endeavour' is a very special Tartan 34C, as you will see from the cutter rig modification, Ratcliffe wind vane auxiliary rudder self-steering, SSB radio, radar, and more.

    Read More