The Fifty 21 is moderately powered for comfortable coastal cruising, with acceptable motion comfort for coastal passages.
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 16.9′, the Fifty 21 tops out around 5.5 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √16.9′ LWL = 5.5 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
16.8
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
25.0%
Light ballast — tends to be tender; reef earlier than the numbers suggest.
Displacement / Length
367
Heavy displacement — a slow, steady, seakindly hull.
Comfort Ratio
21.2
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
2.03
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
486lbs
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
21.2
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
2.03
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
PHRF Fleet Position
Where the Fifty 21 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Holder 20
186s/nm
San Juan 21
258s/nm
Cal 21
261s/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° |
2.2 |
2.8 |
3.1 |
3.2 |
| Close Reach60° |
2.6 |
3.3 |
3.7 |
3.9 |
| Beam Reach90° |
3.2 |
4.1 |
4.6 |
4.8 |
| Broad Reach120–135° |
3.0 |
3.8 |
4.2 |
4.4 |
| Run150–180° |
2.4 |
3.0 |
3.4 |
3.5 |
These are simplified estimates based on hull speed (5.5 kts),
SA/D (16.8), 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 Fifty 21 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–7 kts
7–18 kts
18–26 kts
26+ kts
Ghosting
0–7 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
7–18 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
18–26 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
26+ 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 Fifty 21.
|
Fifty 21 |
Cal 21 |
First 210 Beneteau |
Holder 20 |
Kelt 620 |
San Juan 21 |
| Dimensions |
| LOA |
20.5 |
20.5 |
20.3 |
20.3 |
20.3 |
20.5 |
| LWL |
16.9 |
16.7 |
19.7 |
18.4 |
17.1 |
17.0 |
| Beam |
8.0 |
6.7 |
8.1 |
7.8 |
8.1 |
7.0 |
| Displacement |
3 |
1 |
2 |
1 |
2 |
1 |
| Ballast |
992 |
360 |
772 |
260 |
838 |
400 |
| Sail Area |
263 |
196 |
237 |
194 |
250 |
190 |
| Performance |
| PHRF |
— |
261 |
— |
186 |
— |
258 |
| SA/Disp |
16.8 |
29.5 |
22.3 |
28.2 |
24.4 |
26.3 |
| Bal/Disp |
25.0 |
32.7 |
34.7 |
22.4 |
39.8 |
— |
| Comfort |
21.2 |
7.6 |
10.6 |
6.1 |
11.0 |
8.0 |
| Capsize |
2.03 |
2.59 |
2.50 |
2.98 |
2.54 |
2.60 |
| Hull Speed |
5.5 |
5.5 |
5.9 |
5.8 |
5.5 |
5.5 |