By 16th August, 2021 Blog No Comments

How Do Furling Mainsails Work?

Furling mainsails are far more common on new boats compared to classic mainsails because of their many benefits and ease of use, but we need to learn some key skills to use them properly and efficiently.

The main benefit of a furling main is the easy deployment and retrieval of the sail matched by the safety of not having to flake the sail and secure it while at sea. On the flip side of that, the furling mechanism has many moving parts that all need to work in synchrony for the system to operate properly.

How does a furling mainsail work?

At the base of the mast, and inside the hollow extrusion, is a worm drive (coil, drum, furling mechanism, etc.) that is bolted to the mast via a bracket and connected to a foil that runs to the top of the mast. The foil receives the luff of the mainsail via the bolt rope and the main halyard raises the main to the top of the mast. When the worm drive is spun, via the furling line, the entire foil spins and rolls the sail into the mast.

Once the sail is rigged onto the furling system, the main halyard will no longer be used as the sail have no need to be raised and lowered. Instead, it will be rolled via the two control lines know as the furling line and outhaul.

Like we talked about above, the worm drum spins in one direction to roll the sail in and another direction to roll the sail out. When the furling line is pulled, the worm will spin in a manner that rolls the sail in and when the outhaul is pulled the drum will spin in a manner that rolls the sail out. The outhaul and furling line apply opposite forces to the worm drive, so it’s a requirement to ease one line while the other is being pulled (this allows the worm drive to spin).

For example, to roll the sail out, the outhaul will be pulled (causing the worm to spin) while the furling line is eased.

Like any mainsail, the sail should be deployed while the boat is head to wind.

STOP!

While furling or unfurling, if the system seems stiff or it’s hard to furl, STOP! There is likely a jam somewhere in the sail or control lines and continuing to furl will cause damage. That brings up the point of electric winches… electric winches should not be used to operate the furling control lines. Electric winches do not have feelings and will continue to turn until something breaks. A well-maintained furling system, coupled with a sail that’s in good shape, can be operated by hand. Always stop if you feel it’s hard to operate the furling system.

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