Non Uniform Hole in Deck

[CTsalt12]

Found a great solution on the whaler forums:

PES is better than git-rot in my opinion. It is easier to mix large/small quantities, has longer pot life, and penetrates better. http://www.smithandcompany.org/

Where rot is suspected under glass decking I have taken a 3” long finish nail, bent it 90 degrees, chucked it into a drill, worked the other end into the hole, spun the nail to break up the rot, and sucked out the broken up wood. If the broken up wood is damp, then a 50:50 alcohol/acetone mixture is injected into the hole which combines with whatever water it can find and evaporates out much faster than water alone. Water is strongly miscible with acetone. If acetone bothers one, straight stove alcohol can be used, but evaporates at a slower rate. Once the hole inside is dry (sniff test), it’s time to install some regular epoxy.

Penetrating epoxy (west and system three both have one now), will actually penetrate into wet wood, but with less structural integrity. This stuff uses what seems the most toxic voc’s imaginable, so stay away from the fumes. Mix up a batch and fill the holes full. After awhile it will percolate into the dry substrate and disappear. Continue filling the holes until it stops going away. The hard part is waiting for it to finally cure. In confined areas it can take weeks, sometimes months. Again, the sniff test will tell when it’s time to continue. After the penetrating epoxy has dried hard, the hole will be a hole again, since it is mostly voc with a little bit of resin mixed in. At this point regular epoxy resin is mixed with cabosil, or high density filler if area is subject to high cyclical loads. Inject this into the hole, and when cured it is solid as a rock because it is a rock. Drill to suit and install screw. Too small a pilot hole and plug will crack of course.

I’m betting that penetrating epoxy dissolves some composite materials. Put a few drops on plexi and it will soften it. Doesn’t affect fiberglass or gelcoat though. A call to cpes or West might get an answer about BW foam. Melting the foam would be counterproductive I think. If removing original screws from a boat, as a precautionary measure I always fill the holes with cpes before screwing back together. Can’t hurt, doesn’t cost much, tightens up the screws, and I sleep better. bruce

[gran398]

Sounds good on paper...but...

My concern would be not getting out ALL of the rot. Even just a little damp left...you've basically entombed it.

Many years ago I filled a rotten area on a wooden boat with git rot. I dug out all of the rot, put a heat lamp on it, blow dryer, etc. It was like a cavity within a tree...you could only see so much, you had to "feel" for the rest. Got it good and dry, vacuumed it out. Dumped in the git rot, cured out...then finished it off with epoxy with micro-balloons. I was so proud.

Two years later...six inches below the place I fixed turned to mush.

[GoneFission]

Been there, done that Scott...     Fact is - wood boats and the wood in boats really just wants to be compost - you are just delaying their final disposition.       I've had some good experiences with Git-Rot and other penetrating epoxies, but you have to recognize these are band-aids, not cures.  Replacing the wood is the only real cure, even if it's the core for a fiberglass-covered panel.  

My 63 Chris-Craft Constellation cruiser was a great boat, but fighting rot was a constant battle for the 20 years I owned her.  She had over 6 tons of mahogany, and you get on a first-name basis with your local hardwood or mahogany supplier.  Stripping, caulking, varnishing, and painting become a way of life when you own a wood boat.  But there ain't nuthing more pretty when they are done right!  

[CTsalt12]

Ok so based on everyone's input it seems that a pie plate is the safest bet to avoid further core rot, and also perhaps the easiest.  I am planning on cutting one out and installing the lowest profile, most "flush" plate I can find, seeing as the cooler seat will sit on top of it.  I will simply screw in the cooler seat in a different location more towards the middle of the seat, shouldn't be too much of an issue.  Take a look at the location of where I'm installing the pie plate:

http://www.classicaquasport.com/gallery ... yout_2.png

The black lines I drew are for the gas tank hatch.  The plate will be just adjacent to it (the red circle).  My question is this :  will installing a pie plate here do any structural damage?  What am I going to find when I cut out a hole here?  I assume the stringers will be directly under this spot, and provide support for the floor.  Do I run a risk of cutting the stringers when cutting out the pie plate hole?  Any input would be helpful, especially from any 175 owners or people who've worked on 175's, which is a pretty small population unfortunately.

[Capt. Bob]

I re-read the thread so help me out here.

Are there any photos of this project?

Does this model have a tank hatch or are you thinking about cutting one in? Maybe I missed that in another thread?

Also, the "flush" deck/pie plates I've seen are actually recessed into the deck. That is, the cutout is countersunk to allow the mounting plate to rest flush.

[CTsalt12]

Here are pics of the problem area:

http://www.classicaquasport.com/gallery ... G_0838.JPG

http://www.classicaquasport.com/gallery ... G_0839.JPG

The tank hatch has nothing to do with it.  Long story short is that the area around these screw holes is rotten wood, and it's the spot where my cooler seat gets screwed down.  Here's a image of where the problem area is (orange spot), right outside the gas tank hatch, which I drew on there.  

http://www.classicaquasport.com/gallery ... yout_2.png

Im wondering what is below the floor here, and if I cut out a pie plate to solve the issue if I will do more damage in the process by hitting stringers.

[Capt. Bob]

Well that tank hatch might offer a hint at what's below, that's why I asked.

Still, you could use a hole saw to cut/drill out a section over the screw hole and get at least a peek at what's below. A 2" hole ought to do it.
Hell, you might find you don't a full pie plate but you don't know until you probe. In either case, the hole saw should allow you to remove a deck section with minimal damage should you be close to a stringer.

Good luck.