The Mains’l

Today I purchased my mainsail! 🙂 Last week, Michel gave me the tip that there was a ~17m² catamaran mainsail for sale on Ebay, which looked pretty good. The sail itself is from 2008 but in essentially unused condition. It features three full-length and two partial-length battens. Full-length battens (essentially long strips of flexible but somewhat stiff plastic placed inside batten pockets in the sail) are good for performance, especially when sailing upwind, since they help give the sail a better shape, with a smoother curve. I’d have preferred having all five battens in full length, but fair enough. 😉 It was on offer for 490€ but I got it for 300€. It seems like they had it lying around for a while. I’m not so surprised, it’s from some rather obscure class; no one whom I asked recognized the class symbol. Here’s some stats on the sail:

  • Luff length 7.55m
  • Foot length: 3.15m
  • Head length (it’s a squaretop): 1.30m
  • Sail area (approx.): 16.8m²
  • Sailmaker: Starvoiles

This sail also already features two rows of reef points (to reduce the sail area), which is really good, because it saves me a trip to the sailmaker to have them made (and about a hundred euros). With two rows of reef points, and a selection of jibs / genoas to choose from (I’m thinking roughly 5, 10, and 15m²), in addition to a gennaker, there will be plenty of options to adapt the amount of sail to the present weather conditions.

More after the jump…


The next step for the rig will be to start looking for a suitable beach catamaran mast (it has to sit on a ball joint so you can turn the mast around after all). A Formula 18 mast could be a good option. I also need to start keeping an eye open for a suitable boom. This sail has a pretty long foot, so I may have to opt for a boom from some monohull to get the required length, most beach cat booms are too short.

Having a somewhat lower aspect ratio sail (i.e. a longer foot but not as tall) decreases the upwind performance a bit. Like any wing, the lift-to-drag-ratio is dependent on the aspect ratio of the sail, and the L/D ratio is what gives you good upwind performance. A lower rig has its center of effort closer to the deck though (the lever arm for the force which is trying to knock your boat over is shorter), so you can carry a bit more sail. In the end it’ll be a slight loss when beating to windward, and a slight gain when reaching or running. Since proas tend to have rather low stability, and sloop-rigged pacific proas are exceptionally good at sailing upwind anyway, this was a tradeoff I was happy to make, especially with the sail in such good condition.

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