mildew or other black stuff

I have a two year old year WS Tempest (yellow) that is kept outdoors on a rack under a plastic tarp. I have started to notice black specks in the depressions around the hatchs and cockpit. I guess it’s mildew, has anyone else had this problem and has anyone found an easy way to get it off? Soapy water doesn’t seem to make much differenc.


Is this a plastic boat?
And if so, would some acid based hull wash like is used on gelcoat hurt it? That stuff will take off nearly anything.

It’s a plastic boat.
I tried some bathroom cleaner with bleach in it but it didn’t make much difference.


For future reference…
I think if you get the plastic up/off the boat, so it doesn’t actually make contact with the boat, it will probably help alleviate the problem in the future. The air flow will improve & moisture won’t collect between the boat & the plastic tarp.


Simply leaving it in the sun for several
days will do wonders! I’ve taker the mildew out of and off many things this way.

Scrubbing it with stuff brush and mild detergent/clorine solution before and during won’t hurt either.

When you store it again make sure there is total air circulation around the boat. Do not lay cover on boat.



Several Of the Hints Will Work
You have to kill the mildew in order to be rid of it. Some cleaners will appear to clean the mildew off and it will simply grow right back. Direct sunlight and bleach are the best cures. Use a 50/50 mix of clorox and water. Apply it liberally and let it sit out in the sun for a half hour. The mildew should then be very easy to scrub off.

We suffer from mildew here in the SE due to the high humidity during the summer. If the sun does not hit it it will get mildew on it, here. We have to do the clorox and brush thing twice a year on the house out buildinga and anything else that stays in the shade.

happy paddling,


Clorox, shaken, not stirred.
Bleach. Direct. Not some bathroom cleaner with bleach. Good old basic Clorox. Let sit on black spots. Don’t rub in, just put it there. Anyone ever get mildew on home or especially roof shingles of shake roof, just dump bleach on it. I add a mixture of liquid thickener – used for people with dysphagia, or the inability to properly drink thin liquids-- and it keeps the bleach on the roof for longer direct contact on slanted surfaces. But I digress.