Sonar
Seidelmann Yachts · designed by Bruce Kirby · 1980
keelboatBermuda rig
The Sonar is a 23-foot bermuda rig sailboat designed by Bruce Kirby and built by Seidelmann Yachts, first launched in 1980.
General
| Builder | Seidelmann Yachts |
|---|---|
| Designer | Bruce Kirby |
| Years built | 1980 |
| Hull type | keelboat |
| Rig type | Bermuda rig |
| Construction | — |
| Origin | — |
Dimensions
| LOA | 22.97 ft7.00 m |
|---|---|
| LWL | 19.92 ft6.07 m |
| Beam | 7.87 ft2.40 m |
| Draft (max) | 3.92 ft1.19 m |
| Displacement | 2,100 lb953 kg |
| Ballast | 930 lb422 kg |
| Sail Area | 265 ft²24.6 m² |
Design ratios
Computed from the specs above using the standard formulas. Try the sailboat calculators with your own numbers.
SA / Displacement 25.86 Performance / racer — powered up
Ballast / Displacement 44.3 % Higher = stiffer / more sail-carrying power
Displacement / Length 119 Light
Comfort Ratio 10.0 Racing / light coastal
Capsize Screening 2.46 Better suited to coastal use (> 2.0)
Hull Speed 6.0 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
$15,000 typical range $12,000 – $18,000
⚠ 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.
