The Splinter 21 is modestly canvassed and unhurried, 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 17.0′, the Splinter 21 tops out around 5.5 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √17.0′ 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
13.2
Modestly canvassed — a comfortable, unhurried cruiser.
Comfort Ratio
18.2
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
1.95
Below the 2.0 offshore threshold — acceptable for ocean passages.
Pounds/Inch Immersion
415lbs
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
18.2
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
1.95
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 Splinter 21 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser 150–210
Heavy Cruiser 210–300
South Coast 21
258s/nm
Santana 21
264s/nm
Aquarius 21
267s/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° |
2.0 |
2.5 |
2.8 |
2.9 |
| Close Reach60° |
2.4 |
3.0 |
3.3 |
3.5 |
| Beam Reach90° |
2.9 |
3.7 |
4.1 |
4.3 |
| Broad Reach120–135° |
2.7 |
3.4 |
3.8 |
4.0 |
| Run150–180° |
2.1 |
2.7 |
3.0 |
3.2 |
These are simplified estimates based on hull speed (5.5 kts),
SA/D (13.2), 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 Splinter 21 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–8 kts
8–22 kts
22–30 kts
30+ kts
Ghosting
0–8 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
8–22 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
22–30 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 Splinter 21.
|
Splinter 21 |
Aquarius 21 |
Muscadet |
Santana 21 |
South Coast 21 |
Trotter |
| Dimensions |
| LOA |
21.2 |
21.0 |
21.3 |
21.3 |
21.0 |
21.3 |
| LWL |
17.0 |
18.3 |
18.4 |
19.3 |
14.3 |
18.5 |
| Beam |
6.8 |
7.8 |
7.4 |
7.5 |
6.9 |
6.9 |
| Displacement |
2 |
1 |
2 |
1 |
2 |
2 |
| Ballast |
900 |
665 |
1 |
550 |
625 |
— |
| Sail Area |
163 |
163 |
205 |
189 |
206 |
— |
| Performance |
| PHRF |
— |
267 |
— |
264 |
258 |
— |
| SA/Disp |
13.2 |
17.0 |
17.2 |
21.3 |
20.8 |
— |
| Bal/Disp |
— |
35.0 |
43.3 |
32.4 |
31.3 |
— |
| Comfort |
18.2 |
9.9 |
14.8 |
9.0 |
14.4 |
— |
| Capsize |
1.95 |
2.53 |
2.15 |
2.52 |
2.20 |
— |
| Hull Speed |
5.5 |
5.7 |
5.7 |
5.9 |
5.1 |
— |