Good tips...Sunbrella Waterproofing and Isinglass Cleaner

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Senior Member
Oct 6, 2007
Over the years, I've come across some great boat maintenance tips.* I'd like to share a couple with you folks.

Sunbrella Waterproofing

Have you ever tried those canvas waterproofing liquids from West Marine at $15.00 a bottle to keep your bimini from leaking and not to have*it work.* Here's what*I*have been using for 4 years*and I*guarantee it to prevent leaks for 9 months or better.*

Go to your favorite big box store, Lowes/Home Depot and look for Seal*Krete in the paint area.* Its a waterproofing concrete sealer.* For less that $12.00*I can buy a gallon which will seal my very large bimini 4 times.* Buy yourself a quart hand sprayer which allows you to spray a mist of the sealer onto your fabric.* Its an acrylic material so be careful not to let it run on isinglass or it will not come off.* I keep a water hose handy just in case.* It goes on white but dries clear.

Isinglass Cleaner

My wife and I came across this from another cruiser not long ago.* Pitch your current cleaner and go this route.**I swear it works better than I could imagine.


1 tsp Johnson and Johnson Baby Shampoo
1 qrt Distilled water

Go to Walmart (automotive department) and get yourself a sheepskin mitt and a leather chamois cloth,* Mix up your cleaner in a pail.**Wet the mitt and wash your glass, no need to rinse (no soap in the shampoo), chamois off the moisture, let dry.* It will look great with no streaks or waterspots.*

The sundeck on my trawler has about 42 feet of glass on her.* What took us over 1.5 hours to clean, can now be done in less than 30 minutes, BOTH sides.



-- Edited by dougd1 at 07:37, 2007-12-18
Good tips

The waterproofing treatment recommended by the manufacturers of Sunbrella is 303. We've been using it for the nine years we've owned our boat and it works as advertised. I don't know about any of the other products that claim to do the same sort of thing as we haven't used them. In our climate (PNW) on our boat which is outside all year, not under cover, the 303 does a good waterproofing job for about a year. Then it needs to be applied again. It's very important that the Sunbrella be washed clean before applying 303. If the fabric isn't clean, the 303 will not be as effective or last as long.

There are other sealants that can be applied to Sunbrella to waterproof it and from what we've observed on boats where these sorts of sealers are used, they do a good job UNLESS it's on a piece of Sunbrella that's going to be removed, folded, stored for a cruise, then installed again. These heavier sealants can make the fabric very stiff and difficult to work with. 303 leaves the fabric quite flexible and it's easy to fold up and store when you need to.

Some good friends with a sailboat use Thomson's WaterSeal on their Sunbrella dodger. They say it does a great job of waterproofing, but the WaterSeal makes the fabric quite stiff. However they never remove their dodger so it doesn't matter.

-- Edited by Marin at 19:27, 2007-12-09
Good tips

BTW, Thompson's water seal is just parafin wax dissolved in some petroleum solvent. I used to have the formula, but have misplaced it. You can probably search the web and find it.

That being said, I use 303 on my one piece of canvas, and Lemon Pledge on the isinglass.
Good tips

A buddy of mine had some sanding done on his fishboat.

The sander had a huge belt buckle that scratched the plexiglass windows in the house.

Bu using the floor product for "floors that never need waxing" the scratches mostly vanished.

Good tips

Mop-n-Glo.....of Future....something like that??
Good tips

Ick. Those mop n glo types are acrylics. And will turn yellow in no time out in the sun. THEN try to get that crap off!!!
RE: Good tips


Is that AP 303? If it is, by far the most important function of that product is UV protection and it works so well at this that most all ultralight aircraft pilots use it extensively. Because marine canvas is so very exspensive I'm going to try and eliminate from my fleet.

Eric Henning
30 Willard
Thorne Bay AK
Good tips


The 303 product we use is 303 Fabric Guard. To date we have not used 303 AP. We're more interested in water repelling than in UV protection. Sunbrella is pretty UV resistant and my wife, who makes our new canvas and repairs the canvas that came with the boat, has switched to using GoreTex Tenara thread. It costs a ton, but it will probably outlast the boat. It's the most UV, weather, chemical, mildew, etc. resistant thread on the market today. The longevity of boat canvas is far more dependent upon the integrity of the seams than the fabric itself. But we've had very good luck with the 303 Fabric Guard.
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