The Com-Pac Sun Cat is moderately powered for comfortable coastal cruising, 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 15.0′, the Com-Pac Sun Cat tops out around 5.2 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √15.0′ LWL = 5.2 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
16.6
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
33.3%
Typical cruising ballast — balanced stability and motion underway.
Displacement / Length
258
Moderate-heavy — carries provisions well, deliberate in light air.
Comfort Ratio
13.1
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
2.40
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
2lbs
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
13.1
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
2.40
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 Com-Pac Sun Cat sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser 150–210
Heavy Cruiser 210–300
Hunter 170
258s/nm
Montgomery 17
264s/nm
Vagabond 17
270s/nm
Cornish Shrimper 17
390s/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 |
2.6 |
2.9 |
3.0 |
| Close Reach60° |
2.5 |
3.1 |
3.5 |
3.6 |
| Beam Reach90° |
3.0 |
3.8 |
4.3 |
4.5 |
| Broad Reach120–135° |
2.8 |
3.5 |
4.0 |
4.1 |
| Run150–180° |
2.2 |
2.8 |
3.2 |
3.3 |
These are simplified estimates based on hull speed (5.2 kts),
SA/D (16.6), 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 Com-Pac Sun Cat — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–7 kts
7–20 kts
20–28 kts
28+ kts
Ghosting
0–7 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
7–20 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
20–28 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
28+ 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 Com-Pac Sun Cat.
|
Com-Pac Sun Cat |
Cape Cod Cat |
Cornish Shrimper 17 |
Hunter 170 |
Montgomery 17 |
Vagabond 17 |
| Dimensions |
| LOA |
17.0 |
17.0 |
17.0 |
17.1 |
17.1 |
17.0 |
| LWL |
15.0 |
16.4 |
16.0 |
12.1 |
15.8 |
15.0 |
| Beam |
7.5 |
7.9 |
6.8 |
7.0 |
7.3 |
7.3 |
| Displacement |
1 |
2 |
1 |
478 |
1 |
950 |
| Ballast |
650 |
500 |
— |
— |
550 |
345 |
| Sail Area |
162 |
250 |
178 |
150 |
154 |
— |
| Performance |
| PHRF |
— |
— |
390 |
258 |
264 |
270 |
| SA/Disp |
16.6 |
23.7 |
22.3 |
39.3 |
19.7 |
13.6 |
| Bal/Disp |
33.3 |
22.7 |
— |
— |
39.3 |
36.3 |
| Comfort |
13.1 |
13.0 |
10.8 |
4.1 |
9.4 |
— |
| Capsize |
2.40 |
2.44 |
2.39 |
3.58 |
2.62 |
— |
| Hull Speed |
5.2 |
5.4 |
5.4 |
4.7 |
5.3 |
— |