Full-Length Batten Stiffness

Steve, Thanks for sharing your extensive knowledge and experience in your book series. Accompanied by your videos, they are assisting us in mastering the significant learning curve. Last year, after careful consideration of your discussion of maxi roach full batten mainsails, we made the jump and invested in a new main and car system for our Endeavor 38. Wow! A substantial increase in performance, plus a new sense of confidence in a wide variety of sailing conditions. The new main provides enough drive that we routinely use a much smaller headsail and we have reduced weather helm. However, our battens continue to be a source of frustration. When reefing, furling, or raising the mainsail, the battens bend and flop out of the lazy jacks, dragging the rear third of the sail material with them.

In addition, starting in moderate air, the battens seem to be overly flexible and don’t seem to respond enough when flattening the sail. Additionally, the battens donÕt appear to be stiff enough to control the sailcloth as the main lays on the boom. Our initial diagnosis is that the battens are not stiff enough given the sail size, aggressive roach, and cloth weight (7.5 oz). The fundamental question is how do you tell when you have arrived at the right batten stiffness? I suspect our sailmakerÕs choice of batten material (pultruded 1 5/8Ó glass) was based on the availability of standard materials. If the analysis is correct, what is a source for stiffer battens? Dave

Hi Dave: Glad the maxi-roach main is helping.

Regarding stiffness, there are a series of issues here–and no clear cut formulae. Let’s look at the easy question first.

Regarding batten stiffness and working within the lazy jacks, this is a function of lazy jack design. We favor simple designs, just two legs usually, rigged off the lower spreader on a two-spreader rig. This makes it easy to get the sail past the lazy jacks quickly when hoisting. Batten stiffness should not be a major consideration when the sail is within the lazy jacks themselves–if the position of the lazy jacks on the boom are right (note:we are on mark XX on BEOWULF’s lazy jack system).

Sail stiffness is another issue. There are two components to this. One is supporting the roach of the sail. The second is keeping the sail from flogging when reefing, etc. Sail area, roach, and the number of battens are the variants.

The first thing you want is to always have the roach properly supported, i.e. not sag off to leeward or have the batten go into an “S” curve. Beyond this, anything you do with increasing stiffness is extra weight aloft, for modest gain in handling. How far you go in extra stiffness is a function of how strong your winds are. Note that with overly stiff battens, it will be tough to get shape into the sail in low apparent winds. As to stiffer battens, there are all sorts of carbon, sandwich, solid and tubular battens. Most sail makers have a variety of sources. We have solid carbon/epoxy battens in BEOWULF, supplied by North. Our old battens were pultruded vinylester, solid rectangles, and were also very stiff. These came from Bainbridge (who sell only to sail makers). Hope this helps–Steve

Posted by Steve Dashew  (November 30, 1999)

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