The Gulfstar 50 Kth is moderately powered for comfortable coastal cruising, with a steady, comfortable ride offshore, and respectable in club 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 39.7′, the Gulfstar 50 Kth tops out around 8.4 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √39.7′ LWL = 8.4 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
132s/nm
Cruiser/racer — competitive in club racing, comfortable cruising.
SA / Displacement
14.5
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
30.0%
Typical cruising ballast — balanced stability and motion underway.
Displacement / Length
250
Moderate-heavy — carries provisions well, deliberate in light air.
Comfort Ratio
38.9
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.68
Below the 2.0 offshore threshold — acceptable for ocean passages.
SA/Disp (Calculated)
12.3
Computed from measured I/J/P/E rather than reported sail area.
Pounds/Inch Immersion
12lbs
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
38.9
Good offshore comfort — steady enough for multi-day passages.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.68
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 Gulfstar 50 Kth sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Racer 0–90
Cruiser/Racer 90–150
Cruiser 150–210
Gulfstar 50 Sailmaster
123s/nm
Gulfstar 50
126s/nm
Gulfstar 50 Kth
132s/nm
Cruiser/racer — competitive in club racing, comfortable cruising.
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° |
3.1 |
3.9 |
4.4 |
4.6 |
| Close Reach60° |
3.8 |
4.8 |
5.3 |
5.6 |
| Beam Reach90° |
4.6 |
5.8 |
6.5 |
6.8 |
| Broad Reach120–135° |
4.3 |
5.4 |
6.0 |
6.3 |
| Run150–180° |
3.4 |
4.3 |
4.8 |
5.0 |
These are simplified estimates based on hull speed (8.4 kts),
SA/D (14.5), 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 Gulfstar 50 Kth — 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 Gulfstar 50 Kth.
|
Gulfstar 50 Kth |
Csy 50 Pilot House |
Dickerson 50 |
Gulfstar 50 |
Gulfstar 50 Sailmaster |
Passport 50 |
| Dimensions |
| LOA |
50.0 |
50.1 |
50.0 |
50.0 |
50.0 |
50.0 |
| LWL |
39.7 |
38.6 |
38.8 |
39.7 |
41.0 |
39.0 |
| Beam |
13.7 |
14.0 |
13.8 |
13.7 |
14.5 |
13.5 |
| Displacement |
35 |
34 |
33 |
35 |
41 |
34 |
| Ballast |
10 |
15 |
14 |
10 |
11 |
13 |
| Sail Area |
964 |
1 |
1 |
896 |
1 |
— |
| Performance |
| PHRF |
132 |
— |
— |
126 |
123 |
— |
| SA/Disp |
14.5 |
15.7 |
17.7 |
13.5 |
13.6 |
— |
| Bal/Disp |
30.0 |
43.5 |
41.8 |
30.0 |
29.0 |
38.2 |
| Comfort |
38.9 |
37.8 |
37.5 |
38.9 |
41.2 |
— |
| Capsize |
1.68 |
1.72 |
1.71 |
1.68 |
1.69 |
— |
| Hull Speed |
8.4 |
8.3 |
8.3 |
8.4 |
8.6 |
— |