Mainsail

Mainsail guide: selection and specifications

A mainsail is the primary driving sail set aft of the mast on the main boom or mast track. It accounts for 40–60 % of total sail power and determines balance, helm feel and heavy-weather behaviour. This page details the four core mainsail configurations—full-batten, partial-batten, in-mast furling and storm trysail—plus sizing, reefing and end-of-life options.

Original price was: € 3.970,00.Current price is: € 2.395,00.

Sail Area: 23.2m2
Luff: 10.5m
Foot: 3.75m
Leech: 11m

 2.400,00

Sail Area: 35m2
Luff: 14.5m
Foot: 4.92m
Leech: 15.14m

Original price was: € 5.200,00.Current price is: € 2.400,00.

Sail Area: 29.4m2
Luff: 11.25m
Foot: 4.54m
Leech: 11.9m

Original price was: € 3.750,00.Current price is: € 2.500,00.

Sail Area: 27m2
Luff: 11.27m
Foot: 4.05m

Original price was: € 3.750,00.Current price is: € 2.500,00.

Sail Area: 33m2
Luff: 12.9m
Foot: 4.3m
Leech: 13.5m

Original price was: € 4.350,00.Current price is: € 2.500,00.

Sail Area: 25m2
Luff: 11.68m
Foot: 3.75m
Leech: 12.14m

Original price was: € 3.950,00.Current price is: € 2.500,00.

Sail Area: 50m2
Luff: 16.55m
Foot: 5.9m
Leech: 17m

Original price was: € 3.770,00.Current price is: € 2.595,00.

Sail Area: 30.1m2
Luff: 13.3m
Foot: 3.82m
Leech: 13.74m

 2.735,00

Sail Area: 24.5m2
Luff: 10.9m
Foot: 4.31m
Leech: 11.76m

Original price was: € 4.000,00.Current price is: € 2.750,00.

Sail Area: 28.4m2
Luff: 12.05m
Foot: 4m

Original price was: € 4.695,00.Current price is: € 2.785,00.

Sail Area: 26.1m2
Luff: 12.01m
Foot: 3.69m
Leech: 12.45m

Original price was: € 4.900,00.Current price is: € 2.850,00.

Sail Area: 52.3m2
Luff: 16.1m
Foot: 5.4m
Leech: 16.88m

Definition and key measurements

The mainsail fills the main triangle bounded by mast, boom and tack. Standard dimensions:

P = luff length (mast track from boom to black band)

E = foot length (boom from mast to black band)

Roach = extra curve beyond the straight line from head to clew

Area = (P × E) / 2 + roach allowance

Girths (MGUM, MGM, MGU) control shape when reefed.

Mainsail categories

Full-batten mainsail

Horizontal battens span clew to luff

Zero flutter, maximum projected area

Requires lazy-jacks or Dutchman for flake control

Ideal for performance cruisers and racers

Typical roach 12–18 %, supported by 5–7 full battens

Partial-batten mainsail

3–4 short battens at upper leech only

Easier to hoist and flake by hand

Moderate roach (8–10 %)

Standard on boats under 30 ft or charter fleets

In-mast furling mainsail

Vertical battens or none; zero roach

Rolls inside mast via continuous-line furler

Infinite reef points, single-line cockpit control

Trade-off: 15–20 % less drive than battened mainsail

Cloth: vertical-cut Dacron or hydra-net for roll stability

Storm trysail

Separate sail, bright orange, 15–25 % of working mainsail area

Set on dedicated trysail track parallel to mast

Deep third reef replaces trysail on modern rigs

Required for World Sailing OSR Category 0/1

Procurement and upcycling

Send P/E measurements to info@resail.org for a matched second-hand mainsail or to arrange free collection of your retired sail. Every exchange keeps 20 m² of technical textile in circulation.