I'd try and clean it off and use something more suitable for a marine environment. I've heard there's some chemicals that don't react well with marine grade vinyl and over time can speed up deterioration. I've always been a firm believer in Meguiars, as well as 3M's products, they both make Marine Vinyl Cleaners, Conditioners & Protectors. I've heard a lot of good things about 303 as well.

I only used the Armor all on the dash, never the seats. I will look into the meguiars for the vinyl cleaning. My upholstery guy recommended the 303 products, I think you can pick those up at Checker or most other auto part stores.

Followup on the 3M Marine stuff: thumbs way up
 

I promise to post a follow-up pic (wife has the camera today). As I noted earlier, the dash on my new used 180 was really sun-beat, and I worked it over heavily with the aforesaid 3M Marine Vinyl stuff. Finally got to see the results today (@2 weeks later.) I'm very pleased. There are no more of the chalk-white spots visible in the 'before' pix. It's got a good gleam and feels pliant. The upholstery was in (relatively) better shape but the stuff seems to have helped it as well. If I have a 'nit' - i was hoping the seats would come up a bit brighter/whiter. (I know the orig. color is off-white.) Any suggestions?
Points for 3M on this stuff, I really thought it would be a much harder problem to solve.

Update: restored dash results
 

(see my earlier post for 'before' pix)
2 shots of dash after a heavy-handed treatment with the 3M marine vinyl stuff. I though it was going to be a rip-and-redo job when i first got the boat - never would have expected this kind of restoration. (queue heavenly choir, buy MMM stock...)

Looks great! I used the Meguiars 57 on my dash and it also looks almost as good as new. Now if I could only get the door to my ski locker cleaned, I have tried everything I could think of on that with no luck.

Mr. Clean magic eraser on the ski locker. It'll come out showroom new. :wink_thumbup: