The Islander 47 Alden is with a gentle bluewater motion.
Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
8.3 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 38.7′, the Islander 47 Alden tops out around 8.3 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √38.7′ LWL = 8.3 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
Comfort Ratio
52.8
Very comfortable in a seaway — a genuine bluewater motion.
Capsize Screening
1.52
Below the 2.0 offshore threshold — acceptable for ocean passages.
Hull Speed
8.3kts
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
52.8
Very comfortable in a seaway — a genuine bluewater motion.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.52
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 Islander 47 Alden sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Valiant 47
Ct 47
How It Compares
Side-by-side with the boats most often cross-shopped against the Islander 47 Alden.
| Islander 47 Alden | Bristol 477 | Ct 47 | Dolphin 47 Alden | Tayana 47 Cc | Valiant 47 | |
|---|---|---|---|---|---|---|
| Dimensions | ||||||
| LOA | 46.9 | 47.0 | 46.9 | 46.9 | 47.0 | 47.0 |
| LWL | 38.7 | 37.3 | 37.5 | 34.5 | 40.3 | 40.0 |
| Beam | 13.5 | 13.2 | 13.2 | 13.3 | 14.5 | 13.8 |
| Displacement | 45 | 34 | 29 | 32 | 35 | 30 |
| Ballast | 11 | 15 | 12 | 12 | 11 | 11 |
| Sail Area | — | 968 | 908 | 888 | 1 | — |
| Performance | ||||||
| PHRF | — | — | 111 | — | — | 92 |
| SA/Disp | — | 14.6 | 15.3 | 14.0 | 20.7 | — |
| Bal/Disp | — | 43.3 | 40.8 | 36.7 | 33.4 | 36.7 |
| Comfort | 52.8 | 43.0 | 36.4 | 42.3 | 36.4 | — |
| Capsize | 1.52 | 1.62 | 1.71 | 1.66 | 1.78 | — |
| Hull Speed | 8.3 | 8.2 | 8.2 | 7.9 | 8.5 | — |