Stuart Knockabout
Edey & Duff/Ballentines's Boat Shop · designed by Lewis Francis Herreshoff · 1932
modified long keel and centerboardBermuda rigUnited States
The Stuart Knockabout is a 28-foot bermuda rig sailboat designed by Lewis Francis Herreshoff and built by Edey & Duff/Ballentines's Boat Shop, first launched in 1932.
General
| Builder | Edey & Duff/Ballentines's Boat Shop |
|---|---|
| Designer | Lewis Francis Herreshoff |
| Years built | 1932 |
| Hull type | modified long keel and centerboard |
| Rig type | Bermuda rig |
| Construction | fiberglass |
| Origin | United States |
Dimensions
| LOA | 28.00 ft8.53 m |
|---|---|
| LWL | 22.83 ft6.96 m |
| Beam | 6.92 ft2.11 m |
| Draft (max) | 5.50 ft1.68 m |
| Displacement | 4,000 lb1,814 kg |
| Ballast | 2,400 lb1,089 kg |
| Sail Area | 291 ft²27.0 m² |
Design ratios
Computed from the specs above using the standard formulas. Try the sailboat calculators with your own numbers.
SA / Displacement 18.48 Cruiser — good all-round performance
Ballast / Displacement 60.0 % Higher = stiffer / more sail-carrying power
Displacement / Length 150 Light
Comfort Ratio 19.3 Racing / light coastal
Capsize Screening 1.74 Suited to offshore passages (≤ 2.0)
Hull Speed 6.4 kn Theoretical max displacement speed
How these numbers are calculated
- SA / Displacement
SA ÷ (Disp ÷ 64)^(2/3)— Power-to-weight. < 16 under-canvassed, 16–20 cruiser, > 20 racer.- Ballast / Displacement
Ballast ÷ Disp × 100— Stability/stiffness. Higher carries sail better.- Displacement / Length
Disp(lt) ÷ (0.01 · LWL)³— < 100 ultralight, 100–200 light, 200–300 moderate, > 300 heavy.- Comfort Ratio (Brewer)
Disp ÷ (0.65 · (0.7·LWL + 0.3·LOA) · Beam^1.33)— Motion in a seaway. Higher = more comfortable offshore.- Capsize Screening
Beam ÷ (Disp ÷ 64)^(1/3)— ≤ 2.0 favored for offshore; > 2.0 better for coastal use.- Hull Speed
1.34 · √LWL— Theoretical max displacement speed in knots.
Estimated price
$18,500 typical range $15,000 – $22,000
⚠ Rough estimate only — not market data. Derived from a simple model based on length and hull age; actual asking prices vary widely with condition, equipment, engine hours and location.
