Waterproofing Biminis

[Jolly Roger]

We recently had a two hours horrendous downpour while out on our boat, and the cockpit enclosure leaked like a sieve. We need to waterproof it asap, and I would also like to deepen the color from Royal Blue to Navy Blue if possible.
I can’t find any previous threads, so any suggestions of products would be appreciated.

[s/vPainkiller]

We use a 303 product for this purpose, avail at West Marine and other marine stores. It works really well. We just recently did the Bimini but didn't have time to finish the dodger. The next day we got a shower. Under the Bimini was bone-dry, but the dodger still leaked big time. I'm very satisfied. I have heard of others using products like Thompson's water seal (normally used for wood decking, etc), but cannot comment on it.

I always used the spray bottle in the past, but just recently started using a 4" paint roller. What a huge difference. It's much easier, gets better coverage and you don't get spray in unwanted places (like your plastic). I don't know why I never did this before. I'll never use a sprayer again.

Hope this helps.
Scott

[pete33458]

Ditto 303. I use it on my convertible top as well. I use the spray applicator, but the roller sounds like a good idea, although it would use up a lot of 303.

The main thing with 303 is that it's best to apply it to extremely dry fabric, and in direct sun is even better. pete

[s/vPainkiller]

I bought a gallon of the 303 a couple years ago since I wasn't sure how much it would take to seal the bimini and dodger. So I had plenty left and wasn't afraid of using a lot. Also, how often do you want to mess with this? I wanted a good coat and wanted it to last.

Another plus to the roller idea is that you can only spray when it is calm. You can roll it any time without fear of it getting everywhere. Like I said, I'm sold on rolling vs. spraying.

Scott

[Jolly Roger]

Thanks guys.
I just spoke to the manufacturers of 303 fabric guard. They suggested first cleaning the canvas with 303 fabric cleaner then spray on the fabric guard. The tech fella said the thing to watch for when rolling was over saturation. I guess it will not be difficult to mask off the side windows, but then I do have ten.
I will pick up both at my local WM store tomorrow.

Thanks again, I’ll report back when I’ve used it.

[CaptFrankM]

Is it bad to admit that I thought the header said "waterproofing bikinis"? I couldn't figure out why you would want them to be waterproof!

[southernupdate]

Hi Jolly Roger,
Just a point about masking off the windows. I think it is better if you wipe the fabric guard off as you go, as it does affect the clear, and at least you can see where the overspray is. If you mask off, it seeps in under the tape. You dont see it until you unmask and get a nasty surprise. 303 fabric guard is the way to go for sure. As for the colour change, you would be best to wait till you are ready to re-new the canvas. Hope this helps,
Kim

[belizesailor]

Originally Posted by s/vPainkiller

I bought a gallon of the 303 a couple years ago since I wasn't sure how much it would take to seal the bimini and dodger. So I had plenty left and wasn't afraid of using a lot. Also, how often do you want to mess with this? I wanted a good coat and wanted it to last.

Another plus to the roller idea is that you can only spray when it is calm. You can roll it any time without fear of it getting everywhere. Like I said, I'm sold on rolling vs. spraying.

Scott

+1 on 303...great stuff Ive put a new coat on each season for a few seasons now...works great for about a season. Also coated my old leaky rain gear and worked well for that too.

Important that the material is very clean...any contamination and it will leak there.

[Therapy]

Another vote for 303.

Like any kind of "paint" prep takes longer.

[CarinaPDX]

And another vote for 303.

The Sunbrella-approved method of cleaning is with an equal mixture of soap flakes and chlorine bleach diluted in water. Do not use detergent on acrylics. However, the clear windows need detergent, not soap. Nice trick if you can do it. I don't have experience with the 303 cleaner but would give it a try, right after the soap/bleach.

Never use silicone sealant (e.g. Thompson's) for anything on a boat, for the same reason that silicone sealants can be a problem: remnants of the silicone will remain for a very long time, and prevent anything else (cleaners, sealers) from working.

Greg

[thinwater]

Yes, some water proofers will ruin Strataglass. I've been doing some testing. Some destroyed it utterly in a very short time (too fast to wipe), others were more subtle and slower. Be VERY careful. If you have a scrap piece, test the product.

[Kashmir cat]

Thompson's Waterseal for wood decks works GREAT and is pretty cheap. My bimini has spent 14 years in the hot Florida sun and as a result has become quite threadbare. I can see the sun shining through small pin prick holes in it and it has stretched so much that it pools water in the middle. Two coats of Thompson's Waterseal, applied two years ago has kept it absolutely waterproof even in Florida downpours and it doesn't stain or change the color of the sunbrella.

[Jolly Roger]

Okay, we bought some 303 cleaner and waterproofing yesterday.
My wife cleaned the whole enclosure early this morning, then allowed it to dry - which is no problem in Florida. She then sprayed the waterproof on using a cardboard shield to keep it off the windows.
It rained hard about 5pm this afternoon, and we were amazed to see rain running off the top of the cover like water down a creek.
If it only holds up for a year, I’ll be happy to do it again next season.
Thanks for everyone’s input. Very successful outcome.