I normally just throw them in the swimming pool. It's a small pool, but it's large enough to soak them without 'packing' them in.
If there is a spot that needs to be scrubbed I lay them out on the grass and use purple power (similar to simple green) with a soft brush and hose it off.
Also do the brush routine if they have something on them that I don't want in the pool. When I purchased my trailer sailor, the sails had been stored in an open tote, with a couple bottles of purplish 2 stroke oil, nasty looking stains that came out very easily with the purple power and brush.