The Stuart Knockabout is well-powered with enough sail area to move in light air, with a quick, snappy motion best suited to day sailing, designed for cruising comfort rather than racing.
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 22.8′, the Stuart Knockabout tops out around 6.4 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √22.8′ LWL = 6.4 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
PHRF Rating
189s/nm
Typical cruiser — designed for comfort and ease, not podium finishes.
SA / Displacement
18.5
Powerful cruiser/racer — quick in light air, reef early when it pipes up.
Ballast / Displacement
60.0%
Race-oriented ballast ratio — very stiff and powerful.
Displacement / Length
150
Moderate — a good balance of speed and load-carrying ability.
Comfort Ratio
19.3
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
1.75
Below the 2.0 offshore threshold — acceptable for ocean passages.
Pounds/Inch Immersion
564lbs
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
19.3
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
1.75
Below the 2.0 offshore threshold — acceptable for ocean passages.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
PHRF Fleet Position
Where the Stuart Knockabout sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Sabre 28 1
186s/nm
Stuart Knockabout
189s/nm
Typical cruiser — designed for comfort and ease, not podium finishes.
Cal 28
204s/nm
Pied Piper 28
246s/nm
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 |
3.9 |
| Close Reach60° |
3.2 |
4.1 |
4.5 |
4.7 |
| Beam Reach90° |
3.9 |
5.0 |
5.6 |
6.0 |
| Broad Reach120–135° |
3.6 |
4.6 |
5.1 |
5.6 |
| Run150–180° |
2.9 |
3.7 |
4.1 |
4.3 |
These are simplified estimates based on hull speed (6.4 kts),
SA/D (18.5), 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 Stuart Knockabout — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–6 kts
6–20 kts
20–30 kts
30+ kts
Ghosting
0–6 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
6–20 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
20–30 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
30+ 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 Stuart Knockabout.
|
Stuart Knockabout |
Cal 28 |
Pearson 28 1975 80 |
Pied Piper 28 |
Rozinante Herreshoff |
Sabre 28 1 |
| Dimensions |
| LOA |
28.0 |
28.0 |
28.0 |
28.0 |
28.0 |
28.0 |
| LWL |
22.8 |
22.5 |
24.0 |
21.3 |
24.0 |
22.8 |
| Beam |
6.9 |
9.0 |
9.3 |
8.8 |
6.3 |
9.0 |
| Displacement |
4 |
6 |
7 |
8 |
6 |
6 |
| Ballast |
2 |
2 |
3 |
2 |
3 |
2 |
| Sail Area |
291 |
352 |
395 |
345 |
348 |
391 |
| Performance |
| PHRF |
189 |
204 |
— |
246 |
— |
186 |
| SA/Disp |
18.5 |
17.1 |
16.1 |
13.4 |
15.9 |
17.3 |
| Bal/Disp |
60.0 |
— |
45.0 |
— |
— |
42.0 |
| Comfort |
19.3 |
20.6 |
24.9 |
31.0 |
34.7 |
23.4 |
| Capsize |
1.75 |
1.98 |
1.86 |
1.72 |
1.35 |
1.89 |
| Hull Speed |
6.4 |
6.4 |
6.6 |
6.2 |
6.6 |
6.4 |