This afternoon I wanted somewhere much easier to work, so I got after opening up the area around the exhaust. I know you all know about this problem area, in fact I even knew about it before I bought this boat. But what is hard to get is just how wet this balsa can actually be. Here is a link to a super short video I just did shortly after opening the skin up. Plan is to let the reasonable areas dry out and then do some core replacement around the exhaust. I know some have moved the exhaust up in the transom, but I am thinking about adding a swing down transom step, so the lower exhaust position is better for that. I will be going through all of your info on best practices for this part of the repair.

Here are a couple of images after I removed the core in the transom around the exhaust. What I like to use for core removal in a small area like this is a sharp 1/4" wide chisel. It usually easily penetrates the end grain and lets you pare away by hand only little bits with very little effort. It took only a few minutes to remove this area. Likely though it will take days to dry the glass and I wouldn't be surprised if I have to use some heat too.

I have encountered some other areas where the balsa was really wet, but nothing like this area. This was also the 1st area that the balsa had gone black and I suspect that was because this area being out of the water could get much warmer to speed up the rot.

The area behind the gudgeon appears to be foam. This is the 2nd time I have found foam core in this boat. The first time I thought it might have been a repair area. Was foam used in some key areas on these boats?

Just checked with the meter yesterday afternoon and the exposed balsa in these pictures is now bone dry. The exposed inner skin however was still really wet, so I took the small right angle grinder to it to clean it up a bit and aid the drying process. It is going to go over 100° the next few days with low humidity, so now is a great time to dry this river out.

I didn't have enough to do on the bottom of the boat this morning :-) so I decided to open up the area below the exhaust. I knew this area was going to be wet, but some of it was much worse than I was expecting. I had kind of thought for no good reason there was some kind of glass barrier between the transom and the lower hull, but that is not really the case. So the moisture that was in the transom was also seriously into the hull too. Some of this was extremely rotten so now I can core above and below the exhaust now. Before coring I may create a thin barrier of glass so that any future moisture doesn't find its way so easily into the coring below.

While that fun was going on I have a section behind the keel and near the solid center section under heat and vacuum, albeit with not a lot of vacuum. The film seems to be well sealed to the hull, but I'm losing vacuum through the hull coring so only getting about 4" of Hg. So with the heat and essentially an air current maybe this stubborn area will still dry out.







So the next step is to lightly grind the inner skin to clean it up and let it dry. Followed by some fun grinding of the remaining resin on the old balsa core and then let that dry out. Sooner or later some core will get installed. When I started this morning I had the idea I would be working on the coring on the transom most of the day, but that can now wait until the bottom is ready to get done as well.

This afternoon when it was way too warm to be working outside I came in and reviewed the many forum strings on this transom repair. I saw one detail I had not been thinking about and that was isolating some areas for swim steps, or in my case a small platform. I would have had all of this back together before I had thought about that. I have some high density/high strength stuff that I think would be perfect for isolating the exhaust and creating the internal strength needed for a platform. I am not ready to design the platform just yet, but putting some strength in now is easy enough to do. Thanks all you guys that figured this stuff out first! It was also good to know that my transom is no where near as bad as many have had to deal with. Meter readings near the back stays are all good, as are those around the deck drains. Those holes will get some attention, but nothing very serious. I do get to fill one other unnecessary hole from the old bilge pump outlet that is now routed to the sink drain.

This particular part of the project was pretty fun until I moved the scaffolding a bit and disturbed a bees nest and got bit. It is way more fun and much easier working on a vertical surface than anything on the bottom of the boat. I started by making a cardboard template, because that allowed me to bend it and mark it for various details. I started by cutting the hole in the cardboard for the exhaust and then just went from there. There are some beveled areas next to the rudder reinforcement that had to be dealt with and some stuff along the bottom edge where the hull and transom meet. My plan was to use the cardboard template to get close and then just do the fitting on the high density core with any gaps getting filled with thickened epoxy. So once the cardboard template fit I went to the bandsaw and cut the piece out and drilled the hole for the exhaust slightly oversized, again with the plan that the thickened epoxy would extrude into any gaps and where it didn't I would backfill.

Once everything was fit my plan was to use a large hand screw clamp to hold the bottom edge in place to start. I had predrilled some holes through the inner skin of the transom and once the insert piece and the inner skin was buttered up, I clamped the bottom in place and then went up inside and used some self drilling screws to clamp the hard core into place against the inner skin (the screws were from the inside of the boat out into this core). The thickened epoxy extruded as expected and the screws had to be tightened a 2nd time to fully pull the core firmly into place. Then I back filled any areas that didn't have enough material in them and tapered the edges a bit between the core and the balsa core. I used my gloved finger to force a bit more epoxy around the exhaust to really seal it up. I also noticed that my exhaust tube is fiberglass, so maybe it was replaced at some point in time. So for sure I will have a very good bond between the new hard core material and the exhaust tube.

This repaired area will be incredibly strong and watertight when this all gets glassed over. There will be some fairing required to make this all look good and to my surprise when I was looking and planning for that part of the project I noticed that the transom wasn't really all that flat in the first place. You would have to put a straight edge on it to see the slight curve, but it is curved.

So just a bit more easy work to do on the transom and then it is back to the dungeon, grinding and recoring. grinding, grinding, more grinding...................







One thought that occurred to me as I was using some of the mooched scraps from my brother's boat plant, if you have a boat builder in your area it might be worth the trip to see if you can buy some of their core scraps. This stuff is expensive so it may be possible to work a deal to get some of their off cuts and waste. Don't be too surprised though if what they have left is pretty small stuff, they don't like to throw this stuff away.

The stubborn area on the port side just aft of the keel near the solid center section has now been stripped of the balsa coring. It simply resisted all my efforts to dry it out. Even after removing the coring and cooking the inner skin for several hours yesterday the inner skin glass still wants to read wet with the meter. I have to believe this is from the old vermiculite and resin that dammed the water, or retained it, however you like to look at that situation. I have done a basic grind of this glass too prior to heating it. I have wondered if the remaining residue is messing with the meter. This skin is not terribly thick here, so I really don't want to go too crazy grinding it, or I will end up having to reglass it before recoring it. I think I may just coat it with thickened epoxy and let it harden and then read it again. The other option is to get the vacuum pump back out and heat it while applying a high vacuum. But doing that takes time and I'm ready to rock and roll on this section.

This is the same section that last spring I pulled out more than 48 oz. of water. The area about 20" from the centerline has fully dried and is fine. I was even wondering if there was a source of water that was essentially leaking back in to this area, but there isn't anything obvious like that. I can't cut any further aft either because I am up to my cradle and I need enough hull strength left to support the boat while I reglass.