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Performance

Imx 40 Performance

How the Imx 40 performs on the water — racing handicap, sail-carrying power, stability and comfort.

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The Imx 40 is aggressively canvassed for its weight.

Hull Speed

The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.

7.9 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length. With a waterline of 34.4′, the Imx 40 tops out around 7.9 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √34.4′ LWL = 7.9 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
25.1
Performance-oriented — carries a lot of canvas for its weight.
Capsize Screening
2.02
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Hull Speed
7.9kts
S# (Speed Number)
3.8
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.

Capsize Screening Formula
2.02
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

PHRF Fleet Position

Where the Imx 40 sits on the PHRF handicap spectrum — lower numbers mean faster boats.

Racer 0–90
Cruiser/Racer 90–150
Santa Cruz 40 48s/nm
X 40 48s/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° 3.7 4.7 5.2 5.5
Close Reach60° 4.5 5.7 6.3 6.6
Beam Reach90° 5.5 6.9 7.8 7.9
Broad Reach120–135° 5.1 6.4 7.2 7.5
Run150–180° 4.1 5.1 5.7 6.0
These are simplified estimates based on hull speed (7.9 kts), SA/D (25.1), 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 Imx 40 — based on sail area, ballast, and displacement characteristics.

Ghost
Sweet Spot
Reef
Heavy
0–5 kts 5–16 kts 16–24 kts 24+ kts
Ghosting
0–5 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
5–16 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
16–24 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
24+ 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 Imx 40.

Imx 40 Cc 121 Quest 40 Martin Santa Cruz 40 Schock 40 X 40
Dimensions
LOA — 40.0 40.0 40.0 40.0 40.0
LWL 34.4 35.5 36.5 36.0 35.0 35.1
Beam 12.5 13.1 13.6 12.0 10.0 12.5
Displacement 15 14 12 10 7 16
Ballast 5 5 5 5 1 7
Sail Area 951 846 847 734 682 —
Performance
PHRF — — — 48 — 48
SA/Disp 25.1 23.3 24.9 24.6 29.9 —
Bal/Disp — 39.0 41.6 — — 43.0
Comfort — 19.3 16.2 15.9 13.8 —
Capsize 2.02 2.17 2.33 2.20 2.09 —
Hull Speed 7.9 8.0 8.1 8.0 7.9 —