J/70
J/Boats · designed by Alan Johnstone · 2012
keelboatFractional rigged sloopUnited States
The J/70 is a 23-foot fractional rigged sloop sailboat designed by Alan Johnstone and built by J/Boats, first launched in 2012.
General
| Builder | J/Boats |
|---|---|
| Designer | Alan Johnstone |
| Years built | 2012 |
| Hull type | keelboat |
| Rig type | Fractional rigged sloop |
| Construction | fiberglass |
| Origin | United States |
Dimensions
| LOA | 22.74 ft6.93 m |
|---|---|
| LWL | 20.47 ft6.24 m |
| Beam | 7.38 ft2.25 m |
| Draft (max) | 4.92 ft1.50 m |
| Displacement | 1,790 lb812 kg |
| Ballast | 628 lb285 kg |
| Sail Area | 226 ft²21.0 m² |
Design ratios
Computed from the specs above using the standard formulas. Try the sailboat calculators with your own numbers.
SA / Displacement 24.53 Performance / racer — powered up
Ballast / Displacement 35.1 % Higher = stiffer / more sail-carrying power
Displacement / Length 93 Ultralight
Comfort Ratio 9.1 Racing / light coastal
Capsize Screening 2.43 Better suited to coastal use (> 2.0)
Hull Speed 6.1 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
$23,000 typical range $18,500 – $27,500
⚠ 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.
