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Seadog 30
Designer: Reg Freeman  ·  Builder: Glascade Grp Ltd./Reg Freeman Yachts Ltd. (Uk)  ·  First built: 1966
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About the Seadog 30

Designed by Reg Freeman and built in the UK from 1966 to 1974, this distinctive 30-footer represents British yacht design philosophy of the era with its practical approach to cruising. The triple keel configuration makes the Seadog 30 particularly appealing to sailors who frequent shallow waters or prefer the convenience of drying out upright in tidal harbors—a significant advantage for coastal exploration around the British Isles and similar environments. The masthead ketch rig provides excellent sail handling flexibility, allowing crew to easily balance the boat in varying conditions while reducing individual sail sizes for more manageable handling. With a displacement of 12,765 pounds and substantial ballast ratio, this fiberglass cruiser offers the stability and sea-keeping qualities valued in offshore-capable vessels, though the triple keel design makes it particularly well-suited for coastal and inland cruising. Freeman's design emphasizes seaworthiness over speed, evident in the boat's robust construction and conservative proportions. The Seadog 30's reputation centers on its practical nature and ability to access shallow cruising grounds that would challenge deeper-draft vessels. With only 140 built during its eight-year production run, these boats represent a specialized segment of British yacht design focused on practical cruising versatility.

Core Dimensions
LOA (Length Overall) 30.00 ft / 9.14 m
LWL (Waterline Length) 24.00 ft / 7.32 m
Beam 9.50 ft / 2.90 m
Max Draft 3.50 ft / 1.07 m
Displacement 12,765.00 lb / 5,790 kg
Ballast 4,145.00 lb / 1,880 kg
Sail Area (Reported) 399.00 ft² / 37.07 m²
Headroom 6.00 ft / 1.83 m
Design & Construction
Hull Type Triple Keel
Rigging Type Masthead Ketch
Construction FG
Designer Reg Freeman
Builder Glascade GRP Ltd./Reg Freeman Yachts Ltd. (UK)
First Built 1966
Last Built 1974
Number Built 140
Associations SeaDog Owners Association (UK)
Owner Reviews

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Performance Ratios
SA/Displacement Sail Area to Displacement ratio measures how much sail power a boat has relative to its weight. Higher values mean more performance and speed.
Under 14 — Heavy cruiser, slow14–18 — Cruising sailboat18–22 — Cruiser/racerOver 22 — Performance racer
11.73
Ballast/Displacement Ballast to Displacement ratio shows what percentage of the boat's total weight is ballast. Higher values generally mean better initial stability and stiffer sail carrying.
30–35% — Typical cruiser35–45% — Stiff performance boatOver 45% — Racing oriented
32.47
Displacement/Length Displacement to Length ratio measures how heavy a boat is relative to its waterline length. Lower values mean a lighter, faster boat.
Under 100 — Ultralight racer100–200 — Light cruiser/racer200–300 — Moderate cruiser300–400 — Heavy cruiserOver 400 — Very heavy
412.23
Comfort Ratio Ted Brewer's Comfort Ratio predicts how comfortable a boat will feel in offshore conditions. Higher values mean a steadier, more comfortable motion in a seaway.
Under 20 — Uncomfortably rough20–30 — Acceptable coastal30–40 — Good offshore comfortOver 40 — Very comfortable offshore
38.12
Capsize Screening Formula The USHS Capsize Screening Formula estimates offshore capsize risk. Lower is safer — values under 2.0 are considered acceptable for offshore sailing.
Under 2.0 — Safe for offshore2.0–2.2 — Borderline offshoreOver 2.2 — Coastal use recommended
1.63
Hull Speed Hull Speed is the theoretical maximum speed of a displacement hull, calculated from waterline length. Most cruising sailboats reach this speed in moderate conditions. 6.56 kn
Pounds/Inch Immersion Pounds per Inch Immersion (PPI) tells you how much weight is needed to sink the boat one inch. Useful for calculating how additional gear and stores affect waterline. 814.67 pounds/inch
Engine & Accommodations
Engine Make Perkins
Engine Model 4/107
Engine Type Diesel
Horsepower 36
Fuel Capacity 52 gals / 197 L
Water Capacity 46 gals / 174 L
How It Compares

vs. Arpege 30 Dufour, Clansman 30, Contest 30

This boat Similar boats
Dimensions
LOA
Seadog 30 ★
30.0 ft
Arpege 30 Dufour
30.0 ft
Clansman 30
30.0 ft
Contest 30
30.0 ft
LWL
Seadog 30 ★
24.0 ft
Arpege 30 Dufour
22.0 ft
Clansman 30
21.5 ft
Contest 30
24.9 ft
Beam
Seadog 30 ★
9.5 ft
Arpege 30 Dufour
9.9 ft
Clansman 30
8.0 ft
Contest 30
9.0 ft
Displacement
Seadog 30 ★
12 lbs
Arpege 30 Dufour
7 lbs
Clansman 30
9 lbs
Contest 30
8 lbs
Ballast
Seadog 30 ★
4 lbs
Arpege 30 Dufour
3 lbs
Clansman 30
3 lbs
Contest 30
4 lbs
Sail Area
Seadog 30 ★
399 sq ft
Arpege 30 Dufour
382 sq ft
Clansman 30
375 sq ft
Contest 30
362 sq ft
Performance
SA / Displacement (higher = more powerful)
Seadog 30 ★
11.7
Arpege 30 Dufour
15.7
Clansman 30
13.9
Contest 30
13.6
Ballast / Disp (higher = stiffer)
Seadog 30 ★
32.5 %
Arpege 30 Dufour
Clansman 30
37.3 %
Contest 30
45.4 %
Comfort Ratio (higher = more comfortable offshore)
Seadog 30 ★
38.1
Arpege 30 Dufour
23.0
Clansman 30
36.3
Contest 30
27.6
Capsize Screening (lower = safer)
Seadog 30 ★
1.63
Arpege 30 Dufour
2.01
Clansman 30
1.54
Contest 30
1.75
Displacement / Length (lower = lighter)
Seadog 30 ★
412
Arpege 30 Dufour
Clansman 30
405
Contest 30
254
Hull Speed
Seadog 30 ★
6.6 kts
Arpege 30 Dufour
6.3 kts
Clansman 30
6.2 kts
Contest 30
6.7 kts
Speed Number (higher = faster)
Seadog 30 ★
Arpege 30 Dufour
1.5
Clansman 30
Contest 30
1.8
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