I give up! How do I size a spinnaker?

[Makr0]

I have a fast passage 39.

I would like to purchase a used asymmetrical Spinnaker but I have no idea how to size one. Every site and video seems to say something different.

Can someone break this down simply? Like measure these points, divid by this, add this to that.


Any help is appreciated.

[psk125]

No set formula. The shape and size of asyms varies a lot, depending upon the optimal point of sail the owner wants it for for his boat. A boat the size of yours might have two asyms with luff lengths 10' different from each other, optimized for for two different points of sail. The leech and foot measurements will vary according to the purpose of the sail as well. What works will depend upon how you're flying it too. From a sprit? From the spinnaker pole? From the anchor roller? Each position might call for a different tack line. Finding another FP39 owner who could give you the measurements of his asym would be the most helpful. Otherwise you may simply have to have some trial and error sessions with different sized sails and see what works for you.

[antoha]

No expert, but as a rule of thumb you can say that luff should be no less than forestay length or more generally distance from top spin block to tack attachment point (sprit? Etc). Other dims - look at what you see for sale, the ratio is universal enough to zeroth order (if you’re trying to optimize I’m sure not, but if it’s your first asym spin - why not). I got about 10% over this length for luff, and while it may be a little long, it still works.

Looking at sailboat data you can do with a 60’ luff?