Since the 1990’s, fully battened mainsails have gained in popularity as an option on conventional sloop rigs, and many sailors now automatically assume they’re the best choice – but are they?
The pros….
Their popularity is not without good reason. Matched with lazyjacks and the right batten hardware, they can be easier to handle, stacking neatly on top of the boom instead of blowing all over the deck when you lower the halyard to put the sail away or tuck in a reef. Because the battens tend to hold the sail in shape, it flogs less, which makes for quieter and more relaxing sailing or motor-sailing. The reduction in flogging also puts less strain on the rig, and helps the cloth last longer.
What about performance? Fully-battened sails are often considered to be more powerful because of their use, among others, on some racing dinghies, America’s Cup yachts and high-speed multihulls. But none of these have a permanent backstay – and it’s often the backstay that limits the amount of roach you can build into the sail of a typical modern cruiser or cruiser/racer.
So you probably won’t gain any extra area with a fully battened main on a rig with a backstay.
In light airs, the shape built in by the battens gives these sails an edge when others are hanging limp though. What’s more, their flog-resistance, makes them especially useful for motor-sailing: you can bring the traveller to windward, haul the boom into the middle, and the sail will continue to fill until you’re almost head-to-wind.
The cons ….
But it’s not all good news. Perhaps the most obvious drawback is cost – fully-battened sails are inevitably more expensive. And the ‘locked-in’ shape also has a down-side: because of their ability to keep driving at very fine angles of attack, they’re more difficult to de-power – so you’ll find it harder to slow down or stop in a man-overboard situation, or when picking up moorings. You’ll get used to it, but you have adopt a different style of sailing.
Chafe is something else to bear in mind. Especially on boats with angled spreaders or swept-back rigging (like many multihulls) the battens are going to rub. Whilst we reinforce the pockets with webbing, the answer is anti-chafe patches, but we can’t put them on when building the sail because we won’t know exactly where it’s going to come into contact with the rigging. That’s why we need you to mark the ‘trouble spots’ (or let them mark themselves over the first summer) and let us have the sail back at the end of the season.
Finally, racing sailors may find fully-battened mains less ‘tweaky’ than conventional, soft-batten types. Once again, it’s down to the battens holding the sail in shape, which makes it slightly less responsive to some of the finer controls.
What makes a Kemp sail different?
Being more costly and complex to build than conventional mains, fully-battened sails provide ample scope for sailmakers to cut corners. You may find quotations showing only four battens or pocket terminals in inappropriate ‘soft’ construction materials, to highlight just two examples.
At Kemp, we usually aim to use a minimum of five flat battens – whilst lighter, we find rod can splinter more easily. This way, the high compression loads on the luff (a feature of full-length battens) are more evenly distributed, giving you smoother running cars. Since one of the major benefits of fully-battened sails is their ease of handling, it’s pointless to skimp in such a crucial area.
Of course, the larger the boat (and the bigger the roach) the more battens we use too. Another important feature we always offer is a cunningham hole, because luff tension is essential in fresher winds to move the draft forward and open the leech. Just as important is the right choice of batten end fittings and mast sliders. That’s why we ask you for details of your mast, including its section and a profile of the aft edge; only then can we select the hardware which will ensure the best performance and lowest friction.
The system we most often specify incorporates wheeled cars (usually manufactured by Rutgerson or Selden), which roll up and down the aft face of the mast, either side of the luff groove – a simple, economical and well proven solution. Battens are inserted from either side of the sail, with the leech end captive in solid composite retaining boxes, and tension on the battens achieved using a threaded stainless steel screw adjuster on another solid batten box at the luff.
Other mast interface systems
On some mast sections, neither the Rutgerson or Selden will fit – so we use other solutions, according to the situation.
For larger size yachts, an external track bolted to the mast may be the answer. This ensures a more precise fit between the track and cars for lower friction – essential with the high luff compression loads produced by full-length battens in large sails.
Aftermarket tracks from Tides Marine and Antal offer increasingly costly and more effective means of controlling plain bearing luff cars, and we recommend both of these as options.
If you want the ultimate in low-friction running and don’t mind spending a little more, your choice widens to include ball-bearing systems. Without ball bearings, you’ll generally have to go up to the mast to help the sail right down on to the boom. Introduce a ball race, though, and the sail’s weight should bring it all the way down. Ronstan’s ballslide cars and the ballslide tracks from Ronstan and Harken for even lower friction are examples of these.
We can’t over-emphasise the importance of selecting the correct fittings and mast sliders with full-length battens. Inappropriate hardware can make hoisting, reefing and lowering very hard work – but getting everything to run smoothly doesn’t necessarily involve great expense. It’s largely a matter of ensuring all the components (batten end-fittings, mast sliders and mast section) are compatible. Since the whole idea of a fully-battened mainsail is to make life easier, we believe it’s worth taking a little extra time and trouble to get it right.
Shorter batten options
The popularity of Fully-Battened mainsails tends to be biased towards more modern yachts with new mast designs, with no reference being made to a large number of sailors who own older style yachts.
We often find owners are incorrectly advised towards fully-battened mainsails. A correctly fitting fully-battened mainsail reduces flogging and makes the sail easier to handle, but we created a design brief to incorporate these benefits into a sail which would fit the older style masts and at a cheaper cost.
The problem with fully-battened sails on these masts is the cars which have to be used to transmit the compression from the full length batten into the mast. Use full length battens with normal sliders and you will find that the sail will not go up or come down easily. Use proper compression cars and they can foul on some older style mast gates which are usually located high up from the gooseneck and stand proud of the mast. The answer was staring us in the face: use battens which do not go right to the luff.
Our “Powermain” offers many of the benefits of full batten sails. They will fit any mast type, work superbly with “Packaway” Mainsail Stacking Systems and above all are a fraction of the cost of fully-battened sails since the hardware content is much lower.
They still feature our heavy-duty double skinned teflon reinforced pockets, with a carrier that extends to the luff of the sail, and with our unique velcro closure system on leech. But they also offer a more adaptable sail shape which also reduces flogging and is easy to handle – at a fraction of the cost of fully battened sails.
The “Powermain System” can also be specified with one or more full length battens to provide a balance of benefits too – a “2+2” batten arrangement is something we often get asked for, and for some this is the right solution: as always, our bespoke service can incorporate any features you desire.