For this boat, basically a dinghy with a cuddy, 2oz ripstop would be fine. Storm spinnaker or code zero cloth, as Paul says.

Maybe this would suit you?

 https://fabrictraders.com.au/ripstop-nylon-fabric-in-burgundy-90cm

Would this do?

210 denier nylon.

210 denier nylon

I liked working with Weathermax and I like the end result.  They make a Weathermax LT, which might be worth investigating.  If you decide to cover the sail against UV, why not just use a nice, soft cotton?

Anonymous wrote:

Okay, good start. So I need to find a suitable 4 oz cloth. Paul, I shall be in touch. :)

Like I said on the FB forum, look at spinnaker cloth or the Dacron used for Code Zero sails. Spinnaker rip-stop nylon is likely cheaper than the Code Zero stuff. If you build the sail right, it will be amply strong enough for the job.

Blue Moon's 23 sq m sail is built from Weathermax 80.  I think the material is probably a bit heavy for such a small cambered junk sail.  It does inflate, even in light airs, but not fully until the wind gets over 12 knots.  Even then the material along the battens lies in lazy folds, though most of the panel takes up an excellent shape and that is good enough for me.  I love the feel of the material, heavy and soft.

I might add that I chose the material against Paul Thompson's advice to use something lighter, and am delighted with the sail. Paul's workmanship is the best I have ever seen.  I think 5-6 oz material would have been better for my sail, though I refuse to go to bed with Odyssey!  4 oz material would be the heaviest I'd consider for a Hartley 16, since 10-15 knot winds, 15-20 knots max, and inshore waters would be my sailing window.  Looking forward to crossing tacks with Redwing 11 one of these days.