The Magnum 85 is aggressively canvassed for its weight, 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 24.8′, the Magnum 85 tops out around 6.7 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √24.8′ LWL = 6.7 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
22.9
Performance-oriented — carries a lot of canvas for its weight.
Ballast / Displacement
28.6%
Light ballast — tends to be tender; reef earlier than the numbers suggest.
Displacement / Length
91
Ultralight — responsive and fast, but carries less stores.
Comfort Ratio
11.5
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
2.21
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
712lbs
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
11.5
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
2.21
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
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° |
3.7 |
4.7 |
5.3 |
5.5 |
| Beam Reach90° |
4.6 |
5.8 |
6.5 |
7.0 |
| Broad Reach120–135° |
4.2 |
5.4 |
6.0 |
6.5 |
| Run150–180° |
3.4 |
4.3 |
4.8 |
5.0 |
These are simplified estimates based on hull speed (6.7 kts),
SA/D (22.9), 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 Magnum 85 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–5 kts
5–14 kts
14–22 kts
22+ kts
Ghosting
0–5 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
5–14 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
14–22 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
22+ 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 Magnum 85.
|
Magnum 85 |
Aloha 85 |
Ericson 28 2 |
Etap 28I |
S2 85 |
S2 86 |
| Dimensions |
| LOA |
28.0 |
28.0 |
28.0 |
28.0 |
28.0 |
28.0 |
| LWL |
24.8 |
24.5 |
23.3 |
23.8 |
22.5 |
22.5 |
| Beam |
8.0 |
9.4 |
10.0 |
10.3 |
9.5 |
9.5 |
| Displacement |
3 |
6 |
7 |
6 |
7 |
7 |
| Ballast |
882 |
2 |
3 |
— |
3 |
3 |
| Sail Area |
302 |
395 |
411 |
358 |
— |
390 |
| Performance |
| SA/Disp |
22.9 |
17.8 |
17.2 |
17.1 |
— |
16.2 |
| Bal/Disp |
28.6 |
40.7 |
42.7 |
— |
39.5 |
— |
| Comfort |
11.5 |
20.6 |
21.8 |
17.2 |
— |
24.2 |
| Capsize |
2.21 |
2.00 |
2.05 |
2.24 |
— |
1.94 |
| Hull Speed |
6.7 |
6.6 |
6.5 |
6.5 |
— |
6.4 |