Plywood waterproofing

I picked up a "Mini Max" sea flea,(see www.svensons.com ) that has been mostly completed, for my grandkids. It just needs the steering wheel mount and coaming installed. The problem is that the boat is made out of regular (non-marine) plywood. I figure I'll have to remove the deck to get in at the inside of the hull. I'm looking for suggestions on how to treat all of the wood to make it water proof and allow me to then fiberglass and paint it. I know that I could just paint it with "end-cut" but that's not good environmentally, plus it may not allow paint and fiberglass to stick properly. I'd appreciate any tips, or suggestions any one may have. Thanks

 

Epoxy...expoxy...epoxy. In case I wasn't quite clear...epoxy! NO POLYESTER...Epoxy to seal and glass!

Steve

 

Epoxy.... Yes !

But , more specificly, I would seal all of the exterior wood and end grain with CPES (Clear Penetrating Epoxy Sealer). Then, you can paint it, cover it with glass (not good I've been told) or urethane...

Best of luck

VKRUE

 

Sorry to be ignorant on this subject. I guess I should have made it clear that I've never done this before and it is outside of my province of knowledge. I'm not too sure what you mean. Obviously, use epoxy, but how: in what form, or kind, and what technique? Thanks

 

America187, Basically,
epoxy is a two part resin (I think that is the right term, at least it describes it),
you mix it to its specified percent, could be 50:50 to 5:1 or less.
then you paint it on. You can also thicken it with micro-beads, to turn it into filler. It sets like stone, but will chip.
The CPES should be a much thinner consistency than the 'normal' stuff (that you would also use to lay glass fiber matting or cloth in) and this is why you would undercoat with it- so that it will soak into the wood, preserving that which it penetrates, and also give you a good preperation for the thicker epoxy to stick to.
Epoxy is UV unstable, so you would have to top-coat it with something to protect it. Paint (urethane) or laquer maybe, your choice, paint being much less maintenence.
Good luck,
and read through other threads regarding epoxy, and safety issues.
Hans.

[EDIT- I should note that I am relatively new to all this too, hardly an expert, and am simply relaying stuff that I have recently learned]

 

Cpes

America187

[EDIT- I should note that I am relatively new to all this too, hardly an expert, and am simply relaying stuff that I have recently learned]

DITTO... Same here, that is to say that I am new to this also. Would suggest some research, reading material about building / restoring wooden boats.

It is my understanding that, unlike many years ago, the only real difference between standard plywood and marine plywood is that marine plywood has more plies (layers) than regular plywood and less voids (open spaces where air / water can be trapped and later cause rotting) in the wood. Years ago it used to be made with a different laminating substance also. More plies mean that it is stronger.

As Hansp77 said, I am no pro, but if you seal your woods exterior and end grain with CPES you should be able to paint it without problem.

I am just now finishing up my CPES application and proceeding with filling holes and such with "THICKENED EPOXY" a type of epoxy filler.

There are many types of epoxies. Not all epoxies are chemically compatable with certian other products, so you'll want to do your homework before running out and spending next weeks paycheck on epoxy that may be suited for what you intend to do, and then again... maybe not.

If you check out these peoples website, you can download a copy (FREE) of what they call "THE EPOXY BOOK".
http://www.systemthree.com/about_sys3.asp

Also, You might talk to one of the techs at "The Rot Dr.".
http://www.rotdoctor.com/products/cpes.html

If you decide to go with the CPES I highly recomend purchacing (if you dont already have one) the resperator that filters out organic fumes. That CPES stuff nearly cleared out my whole neighborhood when I mixed up my first batch... Oh, and it's highly flamable too !

Another good source of info is "Wooden Boat Magizine".

As Hansp77 mentioned, a good time spent wandering through the many threads & posts / replies here at Boatdesign.net will reveal much too.

Best of luck

VKRUE

 

to replace the cpes i use laquer thinner mixed into the regular epoxy and hardener mixture...this is my own concoction after reading the tests and ingredients...this is not good for gluing...just a pre-treatment

 

What Works With What?

When waterproofing plywood (or any wood that will live below the waterline) should you also apply some type of fungus/borer repellant (copper arsenic) first?

Also I would really be interested in knowing what works best with what – that is if I use CPES, can I varnish one side (bilge) and paint the other? If I can varnish, should I epoxy first and then varnish?

I would hate to waterproof onlt to find out I also “finish proofed” the wood as well!

 

Texas boater,
both varnish and paint will go over epoxy.
Depending what epoxy, you will probably have to sand it first to get rid of the oily blush that comes out when it cures (amine blush is it?)
For the epoxy, the function of both is to protect it from UV.
Thus, to paint over epoxy is much easier, requiring considerably less coats.
Apparantly they say at least six coats of varnish.
I haven't reached that yet on mine…
Hopefully epoxy lasts a little while in UV!

 

CPES is epoxy. Clear Penetrating Epoxy Solution. The reality of CPES is that is thinned epoxy, It is about 30% epoxy and the rest are different thinners, most, I figure, to cause difficulty to those wishing to copy the formula.

You do not need to pre treat your plywood for marine wood boring organisms, if you plan to encapsulate the plywood with CPES or thinned epoxy. Good bottom paint will provide this protection.

For a good precoat mix 50-50 alcohol and epoxy (any marine brand) and wet down the area several times, until no more epoxy seems to soak in. The wood is now sealed. This sealing process must include any holes, notches or any other type of cut outs that may be there or it does not work nearly as well. The wood must be completely sealed or moisture will get in and rot will begin. This sealer will not increase the strength of the wood, just seal it.

There are many different types of filler materials used to add properties to epoxy. Micro balloons ("beads" was mentioned) is strictly a light weight filler, used to smooth out non-structural areas. Other fillers will be used for making glue, filets, bonding, laminating, etc. WWW.westsystem.com has a good educational site, which you can learn a lot from. All the major epoxy manufactures do, so check them out.

Marine plywood is a fair amount different then exterior grade plywood. The construction of the plywood is much better, the species of the lumber used is very rot resistant and the same species is used throughout the plywood panel. The number of defects, voids, repairs, width of veneer seams, number of veneers per panel, etc. are all superior in marine grade. This is why it costs more, is stronger and lasts longer.

Not all epoxy formulations will develop the amine blush on the surface that other posters have mentioned. Blush is not difficult to remove, but you can work with non-blushing epoxies if you like.

Both paint and varnish will offer UV protection. Paint will offer better protection, because it is not clear. You do not have to varnish the bilge or any other areas that will not be in direct or reflected sun light. Many builders and repair people leave these places with just an epoxy coating. You can see the wood, see leaks, damage, etc., without being hidden by paint. Inside lockers, under floor boards, under seats and countertops, etc. are all places you do not need a top coat for UV protection.

The "Rot Dr" penetrating epoxy is repackaged CPES from Smiths and costs more.

Sorry about the long post.

 

Thanks for the answer - it was just long enough to explain the solution.

 

Hey America187

Once you finish, Would you be so kind to post a Picture?

thanks!

 

keep it simple?

All of the suggestions and info previously posted are very good. Unless you want a project though, why bother? Sounds like the boat won't be kept in the water permanently, trailered I imagine. Good oil based paint will do the trick. I once built a skiff for a lobsterman friend. He wanted fast, cheap, and maintenance free. I used exterior grade fir ply and painted it with exterior grade oil paint. I even used galvanized drywall screws. He paints it every year. Its 7 years old and currently canary yellow and hot pink!

 

amine blush

p.s.

amine blush is a wax additive. Epoxies cure is air inhibited so the wax is added to help it cure. The blush can be washed off with warm soapy water, alcohol or acetone (yuck, very dangerous).

 

man... Im a very dangerous guy I guess...

no offence meant to you pashbe1...

Ive been working At Bloch Mariene for a couple summers now, and If Acetone was "very" dangerous someone there (including me) would have gotten sick and died by now...

If the boat is in a well ventalated area and you wear gloves, or even without gloves (if you dont mind chapped hands) you will be fine... and if your extremely worried about brain cells you can wear one of those white resparators...

now say you were smoking a cigar and using acetone, that would be "very dangerous" in my book...


the stuff you have to watch out for is ":!:Zing:!: " its an acid used to clean algie off of fiberglass bottomed boats...

that stuff will burn your eyes, hands and through your clothes... plus it reaks... and is green... yeah...