Epoxying The Bilges

Discussion in 'Fiberglass and Composite Boat Building' started by WHumphreys, Jul 30, 2009.

  1. WHumphreys
    Joined: Jul 2009
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    Location: Bolton, UK

    WHumphreys Junior Member


    Im going to replace the woodern floors in a GRP boat. At the same time i would like to repaint / seal the bilges. Firstly Im going to remove all the old paint and crud from the grp using RemoveAll 620. Then brush, scrub / rub down with 80s Grit paper and generally make clean with one of West System Cleaning Solvents.

    My question is (and I am a beginner at this so any advise is welcome even regarding the above) Would I Epoxy the bilge GRP and then paint it.

    Im aiming to use all West System GRP products as although not the cheapest being a beginner they are very helpful and it does seem well tested.

    I am also interested in what would be the recommended paint to use.

    Here is the current state of the bilges.

  2. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    I don't know if it is necessary to apply a new coat of neat epoxy to the area, though it rarely hurts my feelings to do so as an additional protective step for any core or damaged fivers that may be exposed. Either way I have had a lot of luck with Interlux Bilgekote, particularly after applying Epoxy Barrier-Kote 404/414 . Again I am not sure it is necessary, but paint is not my area of expertiese so I always follow the directions religously.
  3. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    I happened to snap a couple of photos the past few days. WHumphreys, you asked about paint. I'll post a few photos of the results I've has thusfar with interlux paints and system three epoxy. I've used both west and system three and they are both fine products. The reason I'm partial to system 3 is that it's a 2:1 ratio epoxy and it's simply easier to mix, especially in small quantities.

    Others on this site will have much more experience than me so I'll defer to them regarding the epoxy overcoating.

    The first photo is a sheet of okume 1/2 " after one coat of system three clear coat and two coats of system three general purpose resin were applied over a 36 hour period. Notice the finish is rough from the roller used to apply.

    After allowing the resin coats to cure for a couple of days and sanding with 80 grit and then 120 grit (for about 45 minutes per sheet) you get the sheet on the left in photo two. The sheet on the right is not sanded.

    After applying 2 coats of interlux epoxy prime coat and two coats of interlux perfection you get the finish that's shown in photo's three and four. The finished sheet is compared to an unfinished one.

    The last photo shows the results of new parts vs. old. The vertical cabin wall on the left (right next to the fan) was prepped as stated above (3 coats resin, 2 coats primer, 2 coats perfection) it's a brand new part. The white surface in the center of the photo is the inside of the aft cockpit. This fiberglass assembly is 36 years old. The gelcoat was old and faded, but otherwise in good condition. I followed Interlux's instructions for prepping and laid on 2 coats of epoxy primecoat and 2 coats of perfection. I can't tell the difference between the new part and the 36 year old part!

    My reason for telling you this is that I'm an amateur like you. Follow the instructions to the letter and you'll get great results with Interlux products. Be patient and don't rush! After looking at some of your photos I see that you are where I was a couple of years ago. I think that in your case you need patience, perseverence and plenty of "pounds"!

    I will be using the epoxy primecoat and Interlux bilgecoat on my boat as well. I think that stumble gave some solid advice.

    Regards and best of luck to you,


    Attached Files:

  4. apex1

    apex1 Guest

    Now you have opened the surfaces by solvents and sanding, so you must seal them again. Using neat EP is the right way to choose.
    If the bilge will never see natural light, you could leave the stuff as it is. But a cover layer of paint does´nt harm anyway. You can use the cheapest paint on EP there is almost no difference (except you have a very dirty bilge). The same is valid for the resin! Using West or SP or System three is a waste of money. Mas or other cheap stuff will do exactly the same job. (Mas EP in fact has a advantage over West, it has less Amine blush).
    When it comes to structural properties, like laminating (what so ever, wood, glass) you must choose Epoxy with care, but for sealing the cheapest is as good as the luxury stuff. Do´nt waste your money.
    If there is some sunlight in the bilge you MUST cover the resin for UV protection. paint it twice to be sure you have added enough solid matter to protect. Otherwise use a UV protecting paint. (not UV resistant, that protects only itself not the EP)


  5. Ilan Voyager
    Joined: May 2004
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    Location: Cancun Mexico

    Ilan Voyager Senior Member

    I'm not very fan of chemicals for stripping paint. First it's dangerous stuff, more inside a boat with the vapors, second it's very difficult to clean it totally in a bilge. And using solvents inside a boat, no thanks. I'm too old for that **** and too young to die.

    I like more a sand blaster, even a cheap one at 20 bucks. That needs some personal protection (a very good mask, goggles etc..) but it's dry and it's easy to remove the abrasive and sanded paint with a vacuum cleaner. Also it sands perfectly all the "#%*!!#$" -censored word- little inside corners that makes the life miserable. That leaves a dry surface with some teeth ready to absorb the good epoxy sealer.

    The West System prices are obscene, I dislike its blushing and hate it's tendency to fish eye. Like Apex I prefer the 2/1 epoxies that are more forgiving.

    I use the Raka because it has very little blush if none, very easy to sand without clogging the abrasive, never had fisheye, easy to play with the fast and slow hardener to have the right pot life, flows nicely, can be recoated within the 24 hours without sanding, price is good and Larry is a very serviceable guy.

    I'll add that the resin is a good one, never had a problem of strength or micro fissuring and it' has an extraordinary shell life even in our treacherous climate. Brief I'm a happy customer of Raka.

    Two Coats are a bare minimum, 3 is better. More is useless excepted under an engine. Use a brush, so you are sure to have not entrapped air bubbles in the epoxy. Foam rolls can be tricky in cramped spaces with poor light.
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