Fully Battened Mainsails – The good, the bad, and the ugly
Customers frequently request fully battened sails, whether it’s a Catalina 22 or Swan 58. Is a fully battened mainsail right for you? Or is it just a marketing scheme, a collaboration of sailmakers, hardware manufacturers, and riggers, scheming to separate you from your hard earned money?
Regardless of the type of battens used, we need to be concerned with the following topics:
Ease of hoisting, dousing, and reefing
Controlling sail shape
De-powering without reefing
Before we delve into those topics, let’s discuss why we have battens in the first place. The principal reason is we want to support roach, the material added to the back edge of the sail, beyond an imaginary straight line drawn between the head and clew of the sail. A perk of full battens is some reduction of the loads on the leech; however there are other ways we can address leech loads.
This blog post addresses conventionally rigged boats with backstays. Further, we’re going to limit the discussion to the types of boats most of us sail, monohull cruisers and racer-cruisers. Multihulls, and boats with freestanding rigs like the Freedom, Tanton, and Wylie receive tremendous benefit from fully battened sails because there is no rig induced limitation on roach. Most boats have relatively little room to add significant amounts of roach without the leech hanging on the backstay, or requiring the mainsail to be lowered slightly for tacks and jibes.
Ease of hoisting, dousing, and reefing
Full length battens add weight and friction. With a partial length batten, sail slides tend to pull away from the mast. When we have full length batten, the leech end tends to droop and puts pressure toward the mast on the sail slide. So now we’re asking the slides to be okay with being pushed towards the mast rather than pulled away. These “compression loads” are what make full batten sails harder to hoist, reef, and douse. To compensate for these loads, we’ll often install Strong Track from Tides Marine. This is an elegant yet simple system with an extruded UHMW (ultra high molecular weight) plastic track and stainless steel slides. Strong Track delivers incredible results without relying on cars with bearings and best of all the track comes in one piece and slides up the existing track or groove. Installation takes a fraction of the time of aHarken or Antal system. Best of all, Tides Marine has a great reputation for supporting their products. We can obtain a replacement slide for a track system that is over 20 years old. Compare that to Harken, who told us we were out of luck when we needed hardware for a 6 or 7 year old system that cost the customer over $6000.
The combination of full battens and a track system adds weight. In fact the difference in batten weights and track hardware can really add up. As we know, weight aloft is never our friend. Well, unless it’s your friend who volunteered to go aloft and install the new wind instrument or tri-color light.
Controlling Sail shape
The simplest explanation for the effect of full battens on sail shape is that the battens can take over the shape of the sail, particularly in light air. Another vexing problem in light air occurs when the battens don’t “pop over” when we change tacks. Cunningham, outhaul, and halyard tension don’t have the same effectiveness as they do on a partial full batten sail. One way we can affect shape changes is by bending the mast. So on a boat with a flexible mast and appropriate controls, we can make the needed shape changes. Many boats won’t have adequate range of mast bend to match the shaping ability of a main with conventional battens or just the top one or two full.
Our racing customers generally do not order full batten sails. For cruising customers, we design the sail knowing that the range of controls are limited. The decision on how full or flat the shape of the main is will be made after consulting with the customer on their sailing plans and sailing style.
De-powering without Reefing
As a former sailing instructor for Olympic Circle Sailing Club in Berkeley, California, we taught mainsail de-powering strategies for when you have too much mainsail up. One strategy we taught was backwinding the main, which creates a large bubble towards the luff. Unfortunately, full battens often prevent that bubble from forming. Another technique was the “fisherman’s reef” which is performed by pulling the traveler all the way to windward (yes windward), then easing the sheet considerably.
Every year, a large contingent of cruisers departs the west coast of the Americas, bound for the legendary cruising grounds of the South Pacific. The cruisers with full batten mainsails often find themselves
busy with sail repairs once they make landfall in the Marquesas. Sailing the downwind trades often means the full batten is rubbing against the shrouds. This not only leads to wear on the pockets but can damage the luff box (fitting on luff that holds batten). The boom vang can reduce the up and down movement of the sail during changes in wind velocity. Anti-chafe should be liberally applied and frequently inspected. Swept back spreaders compound wear issues by placing the shrouds so they contact the sail sooner than they would on a rig with straight spreaders. Many modern production boats have swept back spreaders. There are some advantages to a swept back rig outside the scope of our discussion but your rig type should be considered when deciding whether or not to order a sail with full length battens.
Some customers feel that fully battened mainsails are warranted for their ability to reduce flog. As a former charter captain, instructor, and occasional delivery skipper, I disagree and maintain this is more of a seamanship issue. If I’m motoring for an extended period of time, say bringing my boat up from Mexico back to the Northwest, flogging isn’t an issue. Usually I’ll crack off a bit so the main serves as a steadying sail. Otherwise, if I’m motoring straight into the wind in calm sea conditions, I’ll simply drop the sail.
Boats with a backstay don’t require full length battens to achieve the maximum roach possible. Having the top one or two battens full length will allow for plenty of roach and to “max out” the girths under handicap rules.
Stack Height and Slide Spacing
When planning a new mainsail, we like to make customers aware of possible changes in stack height. The length and number of sail slides will dictate how high off the boom the new sail will stack. A fully battened mainsail will have luff boxes at each batten. The slides for the luff boxes will be longer than a regular sail slide. Contrary to popular belief, lazy jack systems and sail covers that integrate lazy jacks still work without full length battens.
How Many Battens?
How many battens is the right number? Most sails will have four or five battens. If we are going to use even slide spacing, there will be a set number of slides between each batten. We don’t have to use even spacing but some of our customers prefer not to have uneven flakes in their sail. Depending on the type of luff hardware, and if there is a track system installed, there are some practical limitations on how much space we can have between the slides. Let’s assume we are designing a mainsail with a luff of 42 feet (12.8m). If we have four battens, we can divide the luff into 5 sections. For five battens, we divide it into 6. Then we divided that result by the number of slides plus one. So doing the math gives us:
4 batten sail – 100.8” (2560mm)
5 batten sail – 84” (2134mm)
The 4 batten slide spacing with 3 slides between battens would be 25.2” (640mm) and with 2 slides, it would be 33.5” (853mm).
For 5 battens, those numbers would be 28” (711mm) or 42” (1067mm).
I met a gentleman who owns a classic 46’ racer cruiser that he lives aboard and cruises with his wife. He’s a dock neighbor of some friends and other customers. He is deciding between a fully battened mainsail versus a mainsail with the top two battens full, and remainder partial. Incidentally, our partial battens are much longer than the old fashioned short leech battens. That helps us avoid what I refer to as “hinge effect wear”. If he opts for the fully battened mainsail, he will need a Tides Marine Strong track system to keep the loads manageable. We’d use Robichaud Epoxy battens for the full batten main. Full batten mainsails cost a bit more to build because of the additional materials and time for the full length pockets. For this particular boat, the additional costs incurred with the fully battened sail will approach $2000. It will be interesting to see what he decides and how he likes it.
About the Author:
Dave Benjamin is president and founder of Island Planet Sails, a leading independent sail loft serving sailors since 2004.