The Portman 36 is modestly canvassed and unhurried, with a steady, comfortable ride offshore.
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 29.3′, the Portman 36 tops out around 7.3 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √29.3′ LWL = 7.3 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
13.8
Modestly canvassed — a comfortable, unhurried cruiser.
Comfort Ratio
34.4
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.67
Below the 2.0 offshore threshold — acceptable for ocean passages.
Pounds/Inch Immersion
1lbs
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
34.4
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
1.67
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 Portman 36 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Racer 0–90
Cruiser/Racer 90–150
Cruiser 150–210
Hunter 36
132s/nm
Islander 36
144s/nm
Watkins 36
201s/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° |
2.6 |
3.3 |
3.7 |
3.9 |
| Close Reach60° |
3.2 |
4.0 |
4.5 |
4.7 |
| Beam Reach90° |
3.9 |
4.9 |
5.5 |
5.7 |
| Broad Reach120–135° |
3.6 |
4.5 |
5.1 |
5.3 |
| Run150–180° |
2.9 |
3.6 |
4.1 |
4.2 |
These are simplified estimates based on hull speed (7.3 kts),
SA/D (13.8), 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 Portman 36 — 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 Portman 36.
|
Portman 36 |
Hunter 36 |
Islander 36 |
S2 110 C |
Sigma 36 Ss |
Watkins 36 |
| Dimensions |
| LOA |
36.0 |
35.9 |
36.1 |
36.0 |
36.0 |
36.0 |
| LWL |
29.3 |
29.5 |
28.3 |
28.3 |
29.0 |
29.3 |
| Beam |
10.5 |
11.1 |
11.2 |
11.9 |
10.3 |
10.5 |
| Displacement |
16 |
13 |
13 |
16 |
15 |
17 |
| Ballast |
6 |
6 |
5 |
6 |
7 |
6 |
| Sail Area |
545 |
604 |
576 |
625 |
545 |
528 |
| Performance |
| PHRF |
— |
132 |
144 |
— |
— |
201 |
| SA/Disp |
13.8 |
17.1 |
16.4 |
15.8 |
14.4 |
12.8 |
| Bal/Disp |
— |
44.4 |
— |
— |
52.0 |
— |
| Comfort |
34.4 |
27.0 |
27.3 |
29.8 |
33.6 |
36.6 |
| Capsize |
1.67 |
1.86 |
1.88 |
1.90 |
1.67 |
1.64 |
| Hull Speed |
7.3 |
7.3 |
7.1 |
7.1 |
7.2 |
7.3 |