Boom Furling system work similarly to slab reefing in the sense that the main is reefed top down unlike in mast furling. The main halyard is dropped and the lower part of the main sail is rolled up into a mandrill located inside the boom.
One critical feature of boom furlers is the angle of the boom to mast. This is specified by the manufacturer and you will need some sort of solid vang to control this angle.
A list of production yachts at the Annapolis Boat Show using Boom furling include; Hylas 70ft, Trintella, Niad, Cabo Rico, Westsail 42, Saga, and Tartan 4400.
There are several Boom furlers including Schaefer BoomFurl, GMT PowerFurl and FurlBoom and Forespar/Leisure furl among others.
Two points of interest in the Boom Furl are the aft track on the mast and the aft furling drum which make retro fitting possible with out huge modifications.
The unique Sail Track and feeder combine to precisely transfer any fully battened main to the mandrel located within the boom. The Sail Track is mounted to the back of the mast to allow the entire system to articulate on the same axis, for easy hoisting, reefing and stowing at any apparent wind angle.
The front end of the Schafer BoomFurl is machined out of a large alloy block. This allows for easy inspection of the Luff tape and furling operation
Placing the furler drum at the aft end of the boom eliminates the need to drill large holes through the mast to mount the drum forward of the mast where it can foul lines.
Forespars Coastal system
Forespars Coastal system is the smaller boat version of the Leisure furl and is shown on the Catalina 30 pictured below. The coastal system has the furling drum in the boom at the aft end and so does not go through the mast, unlike the traditional Leisure furl.
|Boom Furling Pros||Cons|
|Large sail area power||Boom furling most expensive|
|Full battens||Most complex|
|Reef to any sail size||Boom angle critical|
|No boom cover needed|
|Low C of G|
|If it jams you can slab reef|