Independent guide: Follow your spar maker's operating instructions for your specific system.
Quick answer
In-mast furling rolls the mainsail around a vertical rod or foil inside a slotted mast, so the sail can be reefed or stowed from the cockpit. It is very common on production cruisers such as Jeanneau and Beneteau. It trades some sail performance for convenience and needs correct technique and periodic servicing to avoid jams.
Pros and cons
| Pros | Cons |
|---|---|
| Reef from the cockpit at any point of sail | Less sail area and poorer shape |
| No lazy-bag or boom stack | Jams if technique or sail cut is poor |
| Easy short-handed handling | Mechanism inside mast is hard to inspect |
| Sail protected inside the mast | Weight and windage aloft |
Furling technique
- Point the boat close enough to the wind that the main is lightly loaded.
- Ease the mainsheet and vang.
- Keep light tension on the outhaul as you pull the furling line.
- Stop if it becomes hard; unroll a little and try again.
- Never winch the furling line hard.
Maintenance
- rinse the slot and furling gear
- inspect the furling line and its leads
- check the sail's leech and UV condition
- service bearings and the mandrel with the mast out
Related
Frequently asked questions
How do I stop my in-mast furling mainsail jamming?
Keep tension on the outhaul as you furl so the sail rolls tightly, furl with the boat pointing close to the wind so the sail is not loaded, never force the furling line with a winch, and make sure the sail is cut for in-mast furling and not stretched. If it jams, unroll a little and try again rather than forcing it.
Is in-mast furling slower than a slab-reefed main?
Usually yes. In-mast furling mainsails typically have little or no roach and no full battens, which reduces sail area and shape compared with a conventional mainsail. Many cruisers accept this in exchange for easy reefing from the cockpit.