Spinnaker for a 28.5

Jackdaw · Jun 4, 2014

Way way too small.

You need something CLOSE to 37x21.5

It can be a bit smaller, but that one will not fly.

Jackdaw · Jun 5, 2014

Cmp1110 said:
Are those numbers luff and foot ?

Yup.

For a symmetrical spinnaker, the luffs should be about your 'I' measurement. (Technically 95% of your forestay length). The foot should be 1.8 * 'J'.

A kite can be slightly bigger, or slightly smaller, by a foot or so in either direction.

Jackdaw · Jun 5, 2014

Cmp1110 said:
Thanks for the info!!
What about a Cruisin chute, same rules as far as luff and foot ??

In general yes. But:

Depends on where you plan to tack the sail, and how 'reachy' you want it.

The leach will also be shorter than the luff, which makes it asymmetric.

Jackdaw · Jun 5, 2014

Cmp1110 said:
Thank you again for the advice
I plan to tack to the stem head no sprit and I would probably like it more reachy than not we have only a 110 genoa so reaching in light air would be an added advantage

Gotcha.

Mention that to your sail maker. They will probably suggest a sail than will be rather on the flat side, and a luff length designed to have a slight curl when the tack is set all the way down to the stem fitting.

Loosening the tack line will still allow the sail to run deeper and rotate to windward.

Although you might find a good used sail that fits, a custom one will pay big dividends in doing what you want the sail for.

Kinda like this.

http://www.doylesails.com/cruising/downwind/ups/