WARNING! Wood rot.

[Techno]

For anyone out there that just drills a hole through wooden areas of their boat and thinks that this is OK they are way wrong. I just finished drilling new mounting holes for my fuel pump and stuff. Every hole I drilled had wet wood shavings. I don't mean damp but wet.

This is the direct result of some idiot repeatedly drilling holes through the transom support wooden stringers of my STV to mount things and then remounting them (one very large hole is for draining the water from that compartment). None of these holes were sealed after they were no longer needed and more importantly none were sealed ever. The bolts now have an interference fit because the wood swelled and tightend on the bolt.

I suggest that anyone with a highly stressed wooden reinforced part to drill a hole part way into it and check the shavings. this should tell you if the support is strong, or wet and weak.

Drilling a 1/4" hole for a 1/4" bolt is dead wrong. There is no way your going to have the plywood sealed and shove a bolt though the hole- if you even seal the hole. If you don't seal the hole then eventually the wood is going to suck up moisture.

If you drill a hole and slop some resin in the hole it's not sealed, it takes 2-3 coats of epoxy to provide ~ 98% moisture barrier. If you use RTV or silicone, it isn't sealed. the small hole wipes the RTV off and the RTV doesn't penetrate the wood anyway. Try drilling a hole in some scrap wood then sealing a bolt in it, after it's dry take the bolt out and the hole will show what wasn't covered. To make matters worse most RTVs aren't any good for water proofing.

A good way is to drill the hole over sized and refill the hole with epoxy and filler(first swab the hole with unfilled epoxy) then redrill the hole to the correct size after it's cured. this will seal the hole and reinforce the area.

The best way is to drill the hole over sized for a piece of pipe or tubing and then epoxy the tubing in place. Oversized means the pipe isn't jammed in the hole but has enough room to have epoxy filler all around it. This not only seals the hole but also makes the hole stronger for the bolt clamping stress. This is how I mounted the OB on my last boat. Now I have to do it to all the holes I just drilled

BTW. I mentioned in the past that polyester resin won't bond to wood. I was told that it does by someone that never had a problem. Well when I drilled some of the holes the entire fiberglass sheathing on one side pulled away from the wood by the screw action of the bit. This is one reason I sugggest you check for wood dampness.

To fix this wet wood problem I'm going to hook a vacuum pump up to a hole and suck out the moisture( when it gets warmer). After the wood is dry I'll pour a thin type epoxy into the ply from the top. Worked once before.

and that's why I'm looking at Allison now. Wood just does not belong in a boat! I only know of one 'mostly' composite V-king out there, and Virus isnt selling :D
I suppose I should pull the thru-transom exhaust off my big I/O and seal that up with epoxy resin. I wonder what the wood is like around the outdrive??

[JTS Racing]

Well,,,guess I'm screwed:(. Mine is ALL wood except for a few additions. Wood ain't bad if taken care of. But I only come out on sunny days:).

There are several reasons Polyester won't bond to wood. It tends to set quickly, which will not allow enough time to penetrate the wood fibers. Most will mix small batches of resin and mix it to "hot". Balsa is the best to use. Tight fiber woods often have a smooth surface which has to sanded prior to layup. Epoxies may be more expensive but worth it!

Do a little backgroung study of Polyester Resin. Most boats are made of this cheap stuff. It never fully cures and is NOT water proof. Is the leading cause of blistering of boats in the north. Then again it is easy to work with.

[Edited by Hydro.... on 04-21-2001 at 09:43 PM]

[Delta]

Hey Techno.Nice post,but I'm compelled to play Devil's advocate!
Regarding your pipe idea: It sounds like a good idea but it seems to me that by putting in those pipes,you are increasing the density of the transom area in 4 (or 6) isolated areas,thereby not distributing the load equally.You are indeed strengthening the areas immediately around the holes,but then you are inherently forcing all the load onto those areas.Am I making any sense? Wood squishes,pipes don't(relatively speaking).You'll never get the load to squish against the broader area of the wood transom with the pipe in the way.Whatcha think?:confused:
Thanks,Delta

[Techno]

Delta I know what your saying. I got this idea from the gougans bros. (west system) book. They use it for attaching multi-ton keels through the wooden keel.
I try to make the pipe so it's flush with the wood. Problem with clamping onto wood is it's still a local stress load. Thats what those clamp plates are supposed to do for ya. By clamping onto a 3/4"-1" pipe you have up to 3" circumference of load spreading, compared to none on a through bolt. With a through bolt you only get the load spread from the washers pushing on the wood. With the pipe you also get the load spread from the pipe bonded to the inside of the hole.
One reason I like it for the transom is if it leaks, it only leaks water into a pipe. If you use a bolt through the wood I suggest only sealing the water side. This way if it leaks you know about it and can fix it. If you seal the inside too then if it leaks water into the hole you don't know about it and think everything is OK.

The oversized holes filled with filler then redrilled or tapped is also a west system method. If you were to increase the hole from a 1/4" to a 1/2" hole then place a 1/4" fastener in the hole it's supposed to give you 1.5" of grip rather than 3/4"(circumference).

[Liqui-Fly]

The wet plywood would desribe my entire transom before the rebuild this winter. Being in upstate NY in the middle of winter turned my wet transom into a frozen transom:) which really sucked. When drilling holes sealing them can be done a number of ways. The best thet I've found is to heat the hole up with a gun before swabbing in West Sytem epoxy. The heat allows the epoxy to really soak in the wood by decreasing its viscosity. Penetrating epoxies can be used but their quality isn't the same. Thinning West System will also work but heating gives the same results without losing the strength. As for sealing transom holes one common mistake is made....using silicon sealer. It does not penetrate the wood grain and just sits on top. A better choice would be a marine caulk like "Boat Life". Do not use 3M 5200 unless you want the bolts there forever. Plum Crazy told me a little about removing bolts that were sealed with that stuff. But most of all remember it is a boat. If you think it's gonna be dry forever you're wrong. Sometimes too much time is spent on keeping it dry and not enough is spent on making it "ok" for it to get wet. Do the best you can and drive the thing. If nothing else you'll have something to do again in 10 years:). David

What do you think of the rotdoctor.com CPES-type products? I checked out their site, and they did some pretty convincing product tests that shows their sealers putting the west system products to shame! It seemed like some hard evidence. They say it makes a great sealer for exposed wood (better than glass resin.) The original resin has completely peeled away from the seat bases on my Vegas, and I'm going to re-seal them, but I'm planning on using something a little better this time. They say that a board treated with their Clear Penetrating Epoxy Resin will be penetrated to the core of the grain and will last forever. I'm surprised I've never heard any mention of rot doctor stuff on the Scream and Fly boards... anybody who hasn't checked it out might want to get a look. -Chad

[Liqui-Fly]

Penetrating ability requires a low viscosity material and generally to do this with any epoxy it requires an increased in the amount of solvent used in the material. This can greatly effect the final cure strength of the material. Here's the deal....if you boat, part, or whatever it is you're trying to fix requires the "Rot Doctor" it is time to dig out all the roten crap and start over. What is the page for the product? I'd like to read their claims. Seats will always rot in boats unless they are plastic or you laminate the plywood and drill holes to allow moisture to escape. Your Vegas should have no place for the Rot Doctor; it's not a work boat. David

My Hydrostream has never say outside or in the water overnight. There's no rot in there! I'm not talking about rotted wood. They say if you treat GOOD wood with it, it will never go BAD. They say it is the best prep for anything wood that is going into a boat. THAT was what I was talking about. I'm going to chip the old peeling epoxy off my back seat base and drench it with CPES resin instead, which doesn't "stick" to the wood like 'glass resin, but instead soaks into the wood and becomes part of it. Check out their website <url>www.rotdoctor.com</url> and read up on the product tests they conducted. As far as cure strength goes, they say basically that the cured treated wood is stronger than cured West epoxy by itself. West system resins don't get INTO the wood enough to preserve it. I'm going to order some of that CPES resin, I want this boat to last forever. -Chad

[Edited by pyro on 04-24-2001 at 05:27 PM]

[Techno]

I saved the link but haven't read it yet. But I noticed a little advertising scheme there. How strong is thier epoxy by itself? They compare another epoxy without reinforcement to thier own with reinforcement. Not a very fair comparision.
The West system stuff is used to build large sail boats that sit in salt water and haven't failed (wood reinforced plastic). Whatever you seal the wood with you need enough to form a moisture barrrier. If you apply 3 coats of epoxy you have nearly 100%
The other thing is polyester resin(glass resin) is a very poor product for bonding to wood. Epoxy is better, so even if it is thin it's still better than the poly.
I'm not sure how much resin you want in the wood. Wood is a very strong and resiliant product. It will almost never fail in fatigue, just about every other material will.
I only mention this because your boat is a glass reinforced plastic composite. It's not a single sheet of glass, if it was it would shatter.
That product you mentioned might be what I need for my transom braces - once they're dry. It ought to get into and around all the possible voids before it sets up. I don't need high strength just a new bond.

REsins still just "stick" to the outside of the wood, sealing out moisture. Then the boat owner fights with every screw that breaks the barrier. The treated wood CAN'T ROT, so even if there's a leak, it will last forever. As far as wood that is already shot, as long as it's somewhat dry, the stuff turns sawdust into concrete. Their test showed that it will "wick" through new wood grain, 18 inches down the length of the grain of a solid 4"X4" balsa log. If the stuff wasn't so expensive, boat manufacturers would treat all their core woods with it. A waterproof boat, what a concept. They make thicker laminating resins as well for heavy assembly tasks that's supposed to be pretty good stuff, too. I'm very surprised that nobody on the board has ever mentioned their treatments and products. -Chad

[FCnLa]

Polyester resin will not bond to wood, a frank way of putting it, bull****!:eek: I have seen boats broken from wrecks and such an wood was torn apart from itself, not from fiberglass. You must use the correct wood. My first choice is fur. Techno, your boat must be painted on the inside, other wise the wood will discolor under the glass. I also sealed the inside of my boat (all wood bracing) with a clear jel, polyester resin, and wax solution (clear,you can see the wood, looks cool too). This did not even stop the rot on one bulkhead. I must have missed a spot:o. Using metal may or may not work. Metals have a different expansion rate than glass which could cause them to delaminate. That is why wood is used so much (it is cheap too). Over sized holes filled with epoxy and redrilled seem to be the best route to me. And thanks Chad for the site. Good luck!