Naiad 18
Luna Yachts · designed by Mark Ellis · 1984
centreboardCat rigCanada
The Naiad 18 is a 18-foot cat rig sailboat designed by Mark Ellis and built by Luna Yachts, first launched in 1984.
General
| Builder | Luna Yachts |
|---|---|
| Designer | Mark Ellis |
| Years built | 1984 |
| Hull type | centreboard |
| Rig type | Cat rig |
| Construction | fiberglass |
| Origin | Canada |
Dimensions
| LOA | 18.25 ft5.56 m |
|---|---|
| LWL | 17.50 ft5.33 m |
| Beam | 6.00 ft1.83 m |
| Draft (max) | 3.67 ft1.12 m |
| Displacement | 1,100 lb499 kg |
| Ballast | 550 lb249 kg |
| Sail Area | 144 ft²13.4 m² |
Design ratios
Computed from the specs above using the standard formulas. Try the sailboat calculators with your own numbers.
SA / Displacement 21.62 Performance / racer — powered up
Ballast / Displacement 50.0 % Higher = stiffer / more sail-carrying power
Displacement / Length 92 Ultralight
Comfort Ratio 8.8 Racing / light coastal
Capsize Screening 2.32 Better suited to coastal use (> 2.0)
Hull Speed 5.6 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
$9,500 typical range $7,500 – $11,500
⚠ 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.
