The Sirena 40 is well-powered with enough sail area to move in light air, with acceptable motion comfort for coastal passages.
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 31.2′, the Sirena 40 tops out around 7.5 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √31.2′ LWL = 7.5 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
19.7
Powerful cruiser/racer — quick in light air, reef early when it pipes up.
Comfort Ratio
29.2
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
1.88
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
29.2
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.88
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 Sirena 40 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Racer 0–90
Cruiser/Racer 90–150
Santa Cruz 40
48s/nm
Farr 1220
81s/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° |
3.2 |
4.0 |
4.5 |
4.7 |
| Close Reach60° |
3.9 |
4.9 |
5.5 |
5.7 |
| Beam Reach90° |
4.8 |
6.0 |
6.7 |
7.0 |
| Broad Reach120–135° |
4.4 |
5.6 |
6.2 |
6.5 |
| Run150–180° |
3.5 |
4.4 |
5.0 |
5.2 |
These are simplified estimates based on hull speed (7.5 kts),
SA/D (19.7), 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 Sirena 40 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–6 kts
6–18 kts
18–26 kts
26+ kts
Ghosting
0–6 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
6–18 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
18–26 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
26+ 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 Sirena 40.
|
Sirena 40 |
Cc 121 |
Farr 1220 |
Imx 40 |
Pedrick 40 |
Santa Cruz 40 |
| Dimensions |
| LOA |
40.0 |
40.0 |
40.0 |
— |
40.0 |
40.0 |
| LWL |
31.2 |
35.5 |
33.6 |
34.4 |
31.2 |
36.0 |
| Beam |
12.3 |
13.1 |
12.5 |
12.5 |
12.3 |
12.0 |
| Displacement |
18 |
14 |
13 |
15 |
18 |
10 |
| Ballast |
7 |
5 |
5 |
5 |
7 |
5 |
| Sail Area |
843 |
846 |
707 |
951 |
843 |
734 |
| Performance |
| PHRF |
— |
— |
81 |
— |
— |
48 |
| SA/Disp |
19.7 |
23.3 |
20.2 |
25.1 |
19.7 |
24.6 |
| Bal/Disp |
— |
39.0 |
43.9 |
35.1 |
43.9 |
— |
| Comfort |
29.2 |
19.3 |
20.1 |
— |
29.2 |
15.9 |
| Capsize |
1.88 |
2.17 |
2.11 |
2.02 |
1.88 |
2.20 |
| Hull Speed |
7.5 |
8.0 |
7.8 |
7.9 |
7.5 |
8.0 |