In-mast Furling- The Answer to Underperformance

by Adam Loory,GM UK-Halsey Sailmakers International on 25 Apr 2008

The increased sail area of the vertical batten sail can be seen clearly when the old Dacron batten-less sail is laid over the Tape-Drive replacement sail SW

For decades, boats with in-mast furling mains have been sailing around with under performing sails. These hollow-roach sails are starved for power and the boats end up with leeward helm since the mainsail is too small to balance the genoa. BUT, there are a ton of them out there because in-mast roller-furling mains are convenient.

Now sailors with roller-furling mains can replace their poorly performing sails with a main that has positive roach supported by vertical leech battens – the UK-Halsey VB MAX Mainsail. The vertical partial-length battens are parallel to the luff so that the sail can be rolled into the mast.

The battens are staggered so that they will not roll on top of each other making the sail too fat to fit into the mast cavity. Now you can have the convenience of an in-mast roller-furling main with the performance of standard mainsail.

To get an idea of the difference between a Tape-Drive vertical batten main and a Dacron batten-less sail, see the picture to the left of the old Dacron main on top of the new vertical batten main. Both sails are for a Beneteau 411. Notice how much bigger the new sail is.

The finished sail with its roach and vertical battens rolling into the mast © SW

The black lines are the tapes of the new sail underneath the old Dacron sail. The added roach that is possible as a result of the vertical battens makes the sail about 15% larger. The extra roach makes the top of the sail almost 50% wider, which is much more aerodynamically efficient. The extra roach and wider upper sections will increase boatspeed and helm balance greatly.

These pictures shows that you can have a larger, stronger sail that holds its shape better, which is lighter than a smaller, less efficient sail. Just look at the readings on the scales.
© SW

This sail was built for an owner who uses his boat for daysailing, some long-range cruising, as well as some offshore coastal races – basically everything except around the buoys racing.

The sail of choice for this application is UK-Halsey’s Platinum-Drive, which is made with a polyester or Spectra laminate with Carbon Fiber reinforced tapes.

The benefits of a higher tech sail for cruising sailors are many. Tape-Drive sails, are lighter than Dacron, hold their shape much longer, and since the tapes all converge in the corners, they do not need big, bulking, stiff corner patches, which allows them to roll easier.

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