I just bought a Ranger 29 and the covers are very stiff and dirty. They seem to be in good condition for the most part. The boat has not been out of the water since 2003 and I bet it's been at least that long since the covers have been cleaned. Do these need to be professionally cleaned? What are some tips and tricks from out there? Is is possible to throw in a wash machine with some oxyclean or will this ruin the plastic? These are just some ideas I have been bouncing around. Thanks to anyone who can help.