Testimonials
Epoxy, built 1966
Exhaust Port
The first area I had to deal with was the transom. You can see how the area around the exhaust ports was destroyed by rot! This was Mahogany plywood that completely rotted where the bronze exhaust flanges were, at some spots there was barely one ply of wood left. The cost of replacement with new wood in these areas was beyond economic reason, restoration was the only answer. The first order of business was to get "Epoxy" out of the water and let her dry out, not something taken lightly by wooden boat owners. I used small electric heaters and natural ventilation to dry out the transom and surrounding area. This took approximately one week to completely dry. Even though CPES will displace moisture content up to 30% in wood, the dryer the better for faster penetration and absorbency. Using my fingers only, all loose and crumbly wood was removed and a final inspection of the area was carried out to make sure the area was dry. I would like to point out at this time that this area was previously repaired as figure 4 indicates. However, the decay process was not stopped and as a result the new plywood also rotted out!
Generous applications of CPES were made on the inside and outside of the transom. It is very important that you allow the rotten wood to absorb as much resin as possible in a continual process. I would saturate one area till no more resin was absorbed then I would move to the next. I would then return to the original area and so on. This pattern was repeated 3 times inside of one hour. When the CPES would just dribble down and onto the ground I knew the wood was fully saturated.
Here you can see the damage to the old reinforcement plywood. The rot that was in the transom continued on into the new repair. In the background you can see the new reinforcement panels that I will install, they have been generously coated in CPES.
I returned a week later to allow all the solvents to evaporate out of the wood. A close inspection was carried out and indeed the deteriorated area was fully saturated. It was however still weak because so much material was missing. I now had a solid foundation to build the area up and I was not worried about further progress of the rot.
With the rot problem solved, I now focused on returning strength to the area even though the wood was fully impregnated with resin. It was still weak because so much material was missing. I used a mixture of fine sawdust with L & L (Layup and Laminating resin) in a ratio of approximately 1:1. This produced a thick paste that I could apply to the vertical surface with minimal sagging. In this case I used sawdust as a thickening agent because I was working with wood. One could have easily use milled /chopped fiberglass and or Colloidal Silica just match your filler to your substrate. I let this cure for over a week due to the cooler temperatures. The end result I was after was a flexible but rigid area that would last and not be affected by the expansion and contraction of the wood, which would lead to the eventual failure of the repair. I was initially was going to reinforce the entire transom but I was really satisfied with the end result and decided that some additional 1/4 plywood soaked in CPES around the exhaust port was all that was necessary. This was basically only going to act as a washer plate for exhaust port bolts.
When the mixture of L & L (Layup and Laminating Epoxy Resin) and sawdust cured it was like steel, and very difficult to sand, thus Fill-It epoxy wood filler was now used. I wanted to fair the repaired area so a nice smooth transition would take place and it would barely be noticeable. This is a permanent repair that will last longer than the original wood. Our two part epoxy filler (Fill-It) is tenaciously sticky and very easy to apply with a trowel. When cured it produced a very smooth surface that was easy to sand smooth so when the exhaust port was re-installed it was perfectly flat and only a minimal amount of sealant was required. Fill-It can be dyed to better match the original wood but it was not used here as I did not have any available at the time. The wood filler (Fill-It) bonds to the L&L (Layup and Laminating resin, which bonds to the CPES which has been absorbed by the wood fibers themselves, It's not just sitting on the wood but it's inside the wood.
Here you see the repair nearing completion. I dyed some of the Fill-It to illustrate what the repair would look like if you added some colour to the mixture. The middle picture illustrates positioning of the backing plate. Its funny shape is due to the fact that it will also serve as a doubler plate for the swim grid. I mixed our layup and laminating resin with fine sawdust to produce a paste and then squeezed this paste between the backing plate and the transom. This produced a solid yet flexible repair.
This series illustrates the installation of the backing plate. As I squeezed the paste it created a mess (I used way too much) The paste squeezed out the bolt holes and etc... Once the bolts were removed and the area sanded you can see the quality of this repair. The 1/4 plywood serves as and backing plate. The mixture of resin and sawdust is approx 3/8 thick which is the original thickness of the transom. The white material is the Fill-It epoxy filler which will was left its original color so you can see the different stages of repair and materials.
Figures 17 & 18 are very interesting. Because the paste oozed everywhere when I squeezed, it naturally bonded the nuts, washers and everything. I had to clean the bolts with a wire grinder before I could get a socket on them. The washers were pried off with a claw hammer and to my surprise I discovered that the Silicon Bronze washers I thought were solid were only PLATED! You can see how the platting from the washer remained on the transom. Now I do not know if that was just a poor plating job or is this stuff just that sticky!!
Figures 21 & 22 are the final repair. The rot has been stopped and double plates installed for added strength. I used 3m 5200 to secure all thru hull fittings. The white paint you see is Smith & Co high build epoxy barrier paint. Right from the beginning I wanted a waterproof wooden boat and this paint is a key component in this process.