The Block Island 40 Migrator is moderately powered for comfortable coastal cruising, 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 28.0′, the Block Island 40 Migrator tops out around 7.1 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √28.0′ LWL = 7.1 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
16.0
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
39.0%
Stiff enough to carry a big genoa comfortably into moderate breeze.
Displacement / Length
407
Heavy displacement — a slow, steady, seakindly hull.
Comfort Ratio
39.8
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.62
Below the 2.0 offshore threshold — acceptable for ocean passages.
SA/Disp (Calculated)
14.4
Computed from measured I/J/P/E rather than reported sail area.
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
39.8
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
1.62
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 Block Island 40 Migrator sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Racer 0–90
Cruiser/Racer 90–150
Cruiser 150–210
J/40
78s/nm
Irwin 41 Citation
84s/nm
Tartan 41
102s/nm
Caliber 40
120s/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° |
2.7 |
3.5 |
3.9 |
4.0 |
| Close Reach60° |
3.3 |
4.2 |
4.7 |
4.9 |
| Beam Reach90° |
4.1 |
5.1 |
5.8 |
6.0 |
| Broad Reach120–135° |
3.8 |
4.8 |
5.3 |
5.5 |
| Run150–180° |
3.0 |
3.8 |
4.3 |
4.4 |
These are simplified estimates based on hull speed (7.1 kts),
SA/D (16.0), 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 Block Island 40 Migrator — 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 Block Island 40 Migrator.
|
Block Island 40 Migrator |
Caliber 40 |
First 405 Beneteau |
Irwin 41 Citation |
J/40 |
Tartan 41 |
| Dimensions |
| LOA |
40.8 |
40.9 |
40.7 |
40.8 |
40.9 |
40.6 |
| LWL |
28.0 |
32.5 |
35.5 |
33.3 |
35.5 |
32.7 |
| Beam |
11.0 |
12.7 |
12.8 |
13.0 |
13.2 |
12.3 |
| Displacement |
20 |
21 |
18 |
17 |
18 |
17 |
| Ballast |
7 |
9 |
7 |
9 |
7 |
9 |
| Sail Area |
736 |
— |
681 |
787 |
780 |
725 |
| Performance |
| PHRF |
— |
120 |
— |
84 |
78 |
102 |
| SA/Disp |
16.0 |
— |
15.6 |
18.8 |
17.1 |
17.1 |
| Bal/Disp |
39.0 |
44.0 |
41.6 |
54.3 |
41.7 |
51.5 |
| Comfort |
39.8 |
32.4 |
26.0 |
24.9 |
33.6 |
28.0 |
| Capsize |
1.62 |
1.82 |
1.93 |
2.01 |
1.60 |
1.88 |
| Hull Speed |
7.1 |
7.6 |
8.0 |
7.7 |
9.6 |
7.7 |