I had a JR Sadler 25 many years ago, and the sail that I made for her was less than 220gsm. It's never worth getting different, heavier cloth for the top panel (particularly, in your case, as the SJR doesn't stress the cloth unduly). It's more cost- and weight-effective to add another layer only where needed - a wide doubler down the leech, and patches at the corners.

Hi Folks,

I’m getting closer to actually starting the conversion of BooTwo my Sadler 25, at long last.

I’ve been looking around for suitable cloth and have found some cheap coated polyester on EBay that weighs 220 grams per m2 which seems about right  for the 30 m2 SJR sail I’m going to make.

However I was wondering if I should use a heavier cloth for the top panel and if so, how much heavier?

Any thoughts?

Incidentally I bought a sample of the soft Dacron from English Seadog as mentioned by David T in an earlier post. I weighed it and it is just over 300 gsm.