Folding up your sails ?

It depends somewhat on what your sail is made of but yes the numerous creases that stuffing a sail causes will tend to weaken the fibres somewhat and may affect air flow over the sail. Folding or in some cases rolling is worthwhile. Polyester (Dacron) is the least affected but it will damage all fabrics in time.

Also a folded sail takes up less room and is easier to handle.

Gary

I would just jam it in there. If you fold it perfectly each time, you will have a perfect set of creases in your sail...

Or just never stop sailing.

Rolling it up is not a bad option. Folding will cause creases. Your choice(s).