Wildcat F18 – Old sails compared to new sail

Tris...Wildcat F182 Comments

Foot Comparison
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We realised early on that if our intent was to race this boat, we needed to replace the sails. While the sails were in ok condition, they are old and on the point of starting to delaminate. The kite in particular was probably letting more air through it than it was holding. The spinnaker sock was literally falling apart in our hands when we took the boat apart.

We did a lot of research into the different options, but a happy coincidence meant we bumped into Kevin Sproul of Ultimate Sails outside of the Co-op in Hamble. Kevin suggested that the best person to work with was Grant Piggot, of GP Sails. Grant was on our list and Kevin gave him a very strong recommendation. So that helped make the decision easier.

So a couple of phone calls later and we had ordered a full suit of GP sails and a new kite chute.

Having got the new main and jib back home we decided to lay them out against the boat’s existing sails. The new main is a deck sweeper so there are obvious differences, but the overall design differences are interesting.

The Jibs

The jibs are pretty similar, main differences are the luff on the new sail is slightly shorter than the old one. Foot on the new sail drops a little more. We asked Grant to tweak the jib design to give us a bit more power, being a big crew. The chord length of the new jib is slightly longer, off setting the difference in sail area from the shorter luff length. Grant explained that the class rules are very tight, so there is a very limited scope for tweaking the designs.

The Mains

Aside from the obvious with the deck sweeping foot, there are some interesting differences.

We have to bear in mind that the old main is a standard Hobie sail from several years ago, while the new sail is several generations newer in design. But for interest the main points are the difference in the roach and the luff round.

On the old sail there is little or no luff round, it can be seen in the left hand photo underneath the new sail. The lack of luff round will have meant that. generating power from the old design would be a struggle, the sail is already flat, having a straight luff would mean that any mast bend would take the shape out of the sail very quickly. Whereas the luff round in the new sail should mean that we will be able to induce more shape and therefore power into the sail by straightening the mast.

The International Moths have enjoyed great success with deck sweeping sails, although one critical difference is they are sealing against a solid deck while the Wildcat has a porous trampoline, and we wonder if that will have an impact on overall efficiency. Has anyone done a comparison to find out whether that is a factor?

The higher aspect ratio of the new sail will also account for some of the noted performance improvements of the new sail designs. Certainly the new sail looks more tunable with the extra luff round meaning the shape can be tuned for different conditions. Hopefully we can generate more power with that sail, power is good!

2 Comments on “Wildcat F18 – Old sails compared to new sail”

  1. What purchase do you have on the main cunningham? and will you need to increase it now to allow the control?

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