FURLING MAINSAILS
Some sailors swear by mainsail furling systems, others swear at them...
Mainsail furling systems have come on a long way. Sails no longer need to be wrapped around a boom, nor does an in-mast mainsail need to be the hollow-leached, baggy triangle we first saw decades ago. Furling mainsails can now offer more sail area than a traditional slab-reefed mainsail. Be that as it may, every slabreefed sailor knows a horror story about in-mast or in-boom furling that is enough to make them steer well clear, while those that have furling mains wouldn’t put to sea without one.
There is little doubt that furling mainsails are gaining in popularity, even for serious offshore cruising boats. In 2018, 38% of boats sailing round the world in the World ARC had furling mainsail, and Hallberg Rassy reports that almost all new owners buying boats over 40ft opt for furling mains, with Discovery reporting a similar trend.
So has the reputation of furling mainsails been unfairly tainted, and are they more prone to user error, or have the systems ironed out the glitches? Whether you’ve got a furling main on your own boat, or if you’ll be using one when you charter, it’s worth knowing how to avoid the pitfalls of furling mainsails.
HOW DO THEY WORK?
In an age where we expect everything just to be simple and to work, letting off one line, and pulling another to make the mainsail appear or disappear sounds appealing, but what is the best way to furl the mainsail? Is there a correct way to do it?
‘Carefully,’ replies Jeremy White, of Elvstrøm Sails UK. ‘They’re mechanical systems and they need to be operated correctly.’
Whether you have in-boom or in-mast, they both work on a similar principle which anyone with a furling genoa will be familiar with. Inside the mast is an aluminum foil that takes the luff of the mainsail, and in a boom a mandrel takes the foot of the mainsail; both the foil and the mandrel revolve to roll up the sail.
A lot of issues with in-mast furling are caused by the sail not furling properly inside the mast and the furl being too bulky or the sail rubbing on the inside of the mast. Many in-boom problems are caused by an uneven furl with the sail bunching at one end or the other. There are a number of issues to look out for with each system to ensure
stress-free furling.
DIFFERENT OPTIONS
If you’ve bought a new boat that was ‘good value’ and it came with sails, question how good those sails really are. Many original Dacron sails are built to a price that will get you on the water and get you sailing, but they may not be built for longevity or performance unless you’ve specified them and know what you’re getting.
There has been much advancement in furling mainsail design, improved materials, vertical battens, and increased sail area. Many new furling mains present a larger sail area than that of a conventional slab reefing sail. But what should you be looking for when buying a new sail?
‘Whichever sailmaker you choose, get the highest quality material you can afford,’ advises Jeremy. It’s a false economy to buy cheaper sailcloth as it will stretch and you’ll be left with a baggy sail after a few seasons. For example, the luff of laminate sail (on a 45ft yacht) might only stretch 15mm over its lifetime, but on a polyester sail that might be as much as 15 cm. That excess sail has to roll up in the same space as did when it was new.
For those wanting maximum sail area, and sail support, full-length vertical battens are the way forward. These support the leech giving a good full roach, and importantly, they support the sail over its full height which gives it rigidity while it’s being furled, whereas shorter, vertical roach battens can leave the sail unsupported at their base causing furling problems.
For those without the budget or desire for a battened sail using modern materials, a sail with a hollow leech still offers many advantages over a slab reefing system, namely ease of reefing, the ability to set exactly the right amount of sail, and the simplicity of stowing, even if you do lose some power from a smaller sail area and a less perfect aerofoil sail shape.
If you’re having new sails made consider getting them silicone-coated. This helps the sail slide over itself making the furl inside the mast tighter.
UNFURLING
If you were to look down from the top of the mast, the foil usually rolls onto the foil in anti-clockwise direction, that is, the unfurled sail comes off the starboard side of the foil, though it’s worth checking on yours. This is the key to getting in-mast furling to work correctly; trying to furl on a port tack drags the full height of the sail over the side of the mast slot, adding friction where there shouldn’t be any. Furling on starboard tack obviates most of this friction while you furl.
Whether letting the sail in or out, the first thing is to release the backstay (to straighten the mast so the foil doesn’t rub) and put the boat on a starboard tack
– with the wind slightly forward of the beam – this is so the sail feeds cleanly into the mast and around the furler inside.
Unfurling the sail is usually pain-free if the sail was furled correctly. With the yacht on a starboard tack and the wind forward of the beam, release the mainsheet and vang. Ensure the furling line is released then pull out the sail using the outhaul. You shouldn’t need to control the furling line as there should be no pressure on the sail, even on a windy day. If you intend to be reefed, however, don’t let it run unchecked. When the right amount of sail is out, make off the furling line. If you’re reefed, tension the outhaul to give the sail the correct shape (flatter in stronger winds and when close-hauled) then set the mainsheet and vang and away you sail.
FURLING
To furl the sail, after letting off the backstay and putting her on a starboard tack with the wind slightly forward of the beam, let off the mainsheet and then ease the outhaul a little and start to furl.
Always look at the sail as you’re furling – you’ll be able to notice issues as they happen and not after you’ve wound an inch-thick clump of sail through a half-inch gap. If your sail has full-length vertical battens ensure the first batten is parallel with the mast when it enters, and if reefing, leave a batten just outside the mast groove.
Keeping too much tension on the outhaul will drag the foil aft in the mast, bending it and causing the sail to rub against the inside of the mast, creating friction.
Once you’ve taken the slack out of the sail, ease the outhaul and take in on the furling line again. Try not to let the sail flog as this also bends the foil and causes more friction. Repeat the ease-furl process until only the UV protection strip is showing. If you have laminate sails, and they have been furled away wet, try to dry them at the first opportunity.
If you’re having problems furling using the lines, don’t be afraid to go to the mast with a winch handle and furl the sail at the mast. Try it one day, it is remarkably easy.
If you’re having to do anything different, such as raising the boom or chanting a prayer to the god of furling fails, it’s worth looking at your system in detail for problems.