The reason it unwraps is usually because the top of the screecher hasn’t furled tightly – the way to make sure its wrapped tight is to :
a) Furl it facing directly downwind as this allows you to keep the top of the sail taught when furling.
b) Keep some tension on the screecher sheet as you furl it so that it’s pulled down toward the bottom of the furler as this prevents slack sail being wound on at the top of the furl.
You can do this by
– Cleating the sheet on the trolley cleats at the stern (it helps if you turn them round so they are easier to use for this purpose),
– Putting your foot on the sheet while you furl
– Use one hand to keep holding the sheet down while you furl with the other (easier if you have spare crew!).
Hope this helps.
Paul #325, Sydney