wet core in area of hull near thru-hull drain

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gradyrod

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I was going to replace my 2 thru hulls on the sides of my Fisherman204. When I removed one of the thru-hulls I noticed a water soaked core. Upon testing and tapping the area around the thruhull, I noticed that about 1-2 feet is soft around the hole. I dug out the mushy stuff as best I could, but I need some advice as to how to handle this repair. Should I drill small holes beneath the hole right about at the water line and see if any water runs out? Sould I inject some kind of epoxy through holes drilled above the thru hull and from the inside? Anyone familiar with what epoxy might work best (or at all) with a water soaked core?

Thanks for any ideas!

Gradyrod
 
Gradyrod....epoxy won't do much good on wet wood....its got to be dried out....the hole drilling will tell you how far it has gone...and you can re-fill with epoxy when dried to plug the hole...if it's small (just a few inches up and around) you can drill a bunch of holes and let it dry out, but that's probably a low chance of sucess and the spot is probably too big.....this would mean cutting the glass skin from the inside if possible and exposing the core for repair or replacement.....if you can do your exploritory drill holes and post some pics of your application it would help
 
Sounds as if your transom core material is most probably bad, and needs replacing. Not an easy job, but necessary if you plan on keeping boat.
First you need to find the extent of the problem. Do this by removing hardware attaching screws and checking for moisture, drilling into core in various areas sticking in "ice pick" type tools to feel for soft wood. Good areas to start checking are, first and foremost, the infamous "water trap" aluminum angle molding lining exterior edge of transom notch. remove screws and push awl or ice pick into screw hole and see if wood is soft. Next remove screws holding transducers, trim tabs, speedo wheels, on lower exterior transom. If transom core is saturated, water will come out of these screw holes.
If you detect signs of water while doing these checks, you'll need to check even further to see if complete core is compromised. I'll tell you from experience, if you find wet wood in the screw holes holding aluminum angle molding in transom notch area, AND, water comes out from screw holes on bottom of exterior transom, then you need to replace your complete transom core. That is especially true for your boat, since you already state that area around your thru hulls is soft.
It you do not have any attaching screw holes near the bottom of your outside transom area, then drill three or four 1/8" drill holes in lower exterior transom around an 1 1/2" up from lower edge, spacing them every few feet from side to side. Drill these holes only around 1" deep into transom. Don't worry about repairing these holes, they are easily patched with an epoxy/fiberglass flour mix.
Now you should know if your transom is good or bad, If you found no traces of moisture, then perhaps you only have bad wood around thruhullls, and you may be able to remove bad wood in these areas, completely dry, and then apply a "SeaCast" type of curing mixture. If you found water dripping from lower exterior transom holes, then your transom core is probably completely bad. Believe me, it is a lot more common than most owners are aware of. Below is link to a "step-by-step" transom rebuild I did on my mid-eighties Seafarer, after I found that core was shot. The first three pages pretty much describe the complete rebuild, and after that it is more of comments from others. It will let you know what is involved, and what procedures you can follow.

http://forums.bateau2.com/viewtopic.php?f=10&t=19949

Again, this is not easy, and not for the faint of heart, because it requires cutting out and replacing structural sections of your boat, but then again, it isn't rocket science either. If you decide to try and do this repair and need any info, feel free to PM me. Good luck, Mike.
 
Here's what I've done so far...

I drilled holes and used a hack saw blade with a hook to pull out any remaining core mush (there wasn't much). No water came out the drilled holes. I plan to use a heat gun and air compressor to dry out the area as best I can. What's the best way to fill the gap now that I have the two skins and a separation between them?

Thanks!

Gradyrod
 
Gradyrod, how much material around the hole did you actually remove? 1/8 inch? 1/4 inch? 1/2 inch? You mentioned it was soft around the area by 1 to 2 feet, no? If you easily removed stuff around the hole, that was already rotted but I'd bet the remaining material further out is still pretty wet. Epoxy won't bond to it and it must be dry....forget compressed air, the motor will be running for the next month.....if you use a heat gun you will be able to dry the surface and maybe a half inch to an inch below, but you have to be careful on how much heat you're applying or you can delaminate the surrounding skin. Low temperature will be key.

That being said, you can fix the hole with thickened epoxy (depending how far you need to go)....but that remaining 1 to 2 feet of soft core that's wet and not yet rotted will still be there and eventually need replacement long term. The option then would be to replace like Vero Wing did.
 
Get out a piece of paper and draw a sketch of your transom, drill test holes with 1/8 inch drill bit taped for full depth but not thru outer skin, and hold onto whatever material comes out of hole with bit, and mark on diagram, is it dry? cool to touch (means it wet) ?, normal color, or black? Do this on 6 inch centerlines starting along the bottom and work up.

If you have localized the area where it is surrounded by good dry wood.
You can get the largest hole saw sold, usually about 5 inch, use a shorter bit, and saw out the inner skin only, pry it off.
Start in the middle of your sketch. Make a few of these
around the perimeter on the sketch, and do so that good skin remains in any direction for at least 5 inches if using a 5 inch hole saw.
Think of swiss cheese but not so many holes.

Now if the wood is normal color, get a real heat lamp and go at it as close as you can place it, may take many days, but the lamp will suck out all the moisture presuming the area is well exposed as I've directed, you are wasting your time drying out via little holes.
You will even see the water precipitate and run down the inner skin when teh lamp is on and the area heated good.

Keep the lamp as close as possible so that to the touch you can still place you hand on the wood, but barely. Be carefull not to set the gas lines or boat on fire. The wood when wet will never get that hot to burn, not the case when dry, so keep an eye on it.

When the wood stops leaching if it doesr, then you have good wood acceptable to inject the thin penetration epoxies sold to reinforce rotted but dry wood. The dryed wood may look good as is but has diminished structural strenght. Follow instruction sby manufacturer.

Alternately if the area is relatively small, cut out all the inner skin, chop out all wet wood and bevel the remaning good wood, make a matching new plug with plywood and epoxy the plug in place, bevel the edges of the skin holes 2 inches back, then add 3 layers of 1708 on the new marine plywood onto the bevels of inner skin, starting with smaller layer on first.
grind flush.

You just saved yourself a few grand, ought to pay for a full season of gas, at least.

If the areas are all spread out or inaccessible, forget about it.
If the condition of the wood is any worse than above, including black in color which is more like soil than wood, the core can't be saved irrespective of claims by such products.

And find the source of water and seal it off, every screw, thru hull, and bolt into core is a source, all have to be refitted, including rub rail.

Good luck.
 
Thanks Bob, but

could you please tell me what 1708 is?

Great description of how to!! I already have the large hole saw so it' s off to the races! I will do this on the side of the hull though, not the transom.
I don't think the transom is bad at this point.

Gradyrod
 
Wait a minute, where is the wet wood? Transom is rear most surface flat wood straight across.

The side of the hull on your model is not cored, as I know it, nor is bottom.
 
The mystery continues...

GR....can you post a pic of the damage....it will be easier to see what's going on and determine the proper repair...too many open questions at this point.
 
Side of hull is cored..

Bob-

The hole I'm referring to is in the side of the boat, not the transom. It was a drain for a locker, not the cockpit drains in the transom.

I did pull out a bunch of wet material (core) and right now the area is drying out. I plan to add reinforced epoxy with some glass mat and push that up into the cirular area around the hole. Then I plan to glass over the hole with 3 or 4 layers of matt attached on the inside of the hull. Finally, I will redrill the hole for the thru hull and reinstall in the exact same location.

Gradyrod
 
You are fortunate it's not the transom!

Glad to hear it, got away on the cheap!

Grady used ply and checkerboard ply on various areas as core material, for instance under most horizontal surfaces.

You should have no continuous core on side and bottom hull, may be a few strips along side and here and there.
 
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