cleaning hypalon inflatable boat

[1 FMF]

what will clean hypalon effectively?

It's an Avon (west marine) 10' RIB inflatable boat. The hypalon, not the fiberglass bottom, has some stains on it. The usually automotive vinyl cleaner I use doesn't have any effect. Is the 3M vinyl cleaner any good?
If anybody has had any luck, give me some ideas.
I have one big red stain, it looks like a throwable cushion that was red sat on the boat and the dye from it got on the boat.

 

[1 FMF]

looks like it's potassium hydroxide.
picked up some krazy kleen from boat store. main ingred. is KOH. The "inflatable/Dingy cleaner" that's marketed by either avon or zodiac, for twice the price, has same main ingredient.
The 3m vinyl cleaner looks/smells like cheap all purpose cleaner.

 

[Gary Allan]

Do you mean Hypalon®? If so, it's what we used on our older lagoons. Pretty tough stuff for chemical insult. I don't know what cleans it stain-wise (ours was black)..but we used acetone for prepping the surfaces for repairs.