The Bunyip 20 is aggressively canvassed for its weight, with a quick, snappy motion best suited to day sailing.
Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 18.6′, the Bunyip 20 tops out around 5.8 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √18.6′ LWL = 5.8 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
SA / Displacement
46.1
Performance-oriented — carries a lot of canvas for its weight.
Displacement / Length
49
Ultralight — responsive and fast, but carries less stores.
Comfort Ratio
2.3
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
4.96
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
4lbs
Weight needed to sink the hull one inch — loading sensitivity.
Motion & Offshore Suitability
Two ratios that matter most when you're planning passages — how the boat feels in a seaway, and whether the hull geometry is suitable for open ocean.
Comfort Ratio
2.3
Quick, snappy motion — better for day sails and racing than long passages.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
4.96
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
Estimated Speed by Wind
Rough boat speed estimates at different true wind speeds and points of sail — derived from hull speed, SA/D, and displacement, not measured polars.
| Point of Sail |
6 kts TWS |
10 kts TWS |
15 kts TWS |
20 kts TWS |
| Close-hauled40–50° |
2.7 |
3.4 |
3.8 |
4.0 |
| Close Reach60° |
3.3 |
4.2 |
4.7 |
4.8 |
| Beam Reach90° |
4.0 |
5.1 |
5.7 |
6.2 |
| Broad Reach120–135° |
3.7 |
4.7 |
5.3 |
5.7 |
| Run150–180° |
3.0 |
3.8 |
4.2 |
4.4 |
These are simplified estimates based on hull speed (5.8 kts),
SA/D (46.1), and empirical efficiency curves — not instrument-measured
polars. Real-world speed varies with sea state, bottom condition, sail trim, and current.
Speeds in gold approach hull speed;
bold gold means near or at hull speed.
Wind Range & Comfort Envelope
Estimated wind ranges for comfortable sailing on the Bunyip 20 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–5 kts
5–16 kts
16–24 kts
24+ kts
Ghosting
0–5 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
5–16 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
16–24 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
24+ kts
Storm conditions. Storm jib or bare poles. Seek shelter if coastal.
How It Compares
Side-by-side with the boats most often cross-shopped against the Bunyip 20.
|
Bunyip 20 |
Astus 201 |
Hobie Fox |
Nacra 20 |
Shark Catamaran |
Tornado Catamaran |
| Dimensions |
| LOA |
20.0 |
20.0 |
20.0 |
20.0 |
20.0 |
20.0 |
| LWL |
18.6 |
19.2 |
— |
— |
17.0 |
— |
| Beam |
11.0 |
12.7 |
8.5 |
8.5 |
10.0 |
10.0 |
| Displacement |
700 |
838 |
419 |
390 |
300 |
300 |
| Sail Area |
227 |
— |
146 |
— |
235 |
235 |
| Performance |
| SA/Disp |
46.1 |
58.2 |
41.8 |
— |
84.0 |
— |
| Comfort |
2.3 |
2.2 |
2.1 |
1.9 |
— |
1.2 |
| Capsize |
4.96 |
5.41 |
4.55 |
4.66 |
— |
5.98 |
| Hull Speed |
5.8 |
5.9 |
5.5 |
5.5 |
— |
5.5 |