I was reluctant to follow Chris Tate's suggestion to peel the exterior skin and simply dry the core directly. I was concerned about all the fairing that would come with that approach. Well I am over that now. Glassing and then fairing is way easier than replacing core and then glassing and fairing. It is also reatively fast. I can score the skin, shear it off with the impact chisel, clean up the end grain balsa and just start drying it. Without any skin on the balsa it can be dried from crazy soggy to dry in about 1-1/2 hours with the Mr. Heater and that is also checking the hull from the inside to make sure it is dry too. So this is pretty manageable.

The cleaned up end grain balsa is pretty fair as a starting point for the glass work. There are some areas that still have to be recored, but I've sorted that out pretty well already by simply using some chunks of core a little larger than the area to be replaced, marking that with a Sharpie and then just using an actual sharp wood chisel to shave bits off and away. Then just insert the new core section and move on.

I have been a little surprised at how well the balsa dries and it even firms up really well (even in areas that were squishy like a sponge). I can get the balsa to read almost the same as the new Divinycell with my meter and that is after checking the next day.

I scored the glass into about 4" x 4" squares with the angle grinder and an abrasive blade. This size make shearing the skin with the impact chisel pretty easy. There is still a bit of chopped strand mat to clean up with the 36 grit, but that also goes quickly.

Once the end grain looks clean I use the meter again to put the readings back on the balsa and apply the heat. Then what I have seen is that some small areas don't want to dry, so I clean the end grain up again with the 36 grit and reapply the heat.

Prior to doing any new glass I plan to fill in any divots and will check the surface with a fairing stick and will fill and fair as needed to give the new glass a good starting point. New glass will be going all the way to the waterline, even where the skin was not removed.







This adventure is now back on track.

I need to add a couple of corrections here. Getting the exterior skin off is a pretty quick process, but fully grinding the resin off to get the end grain completely bare takes more effort and time than I indicated. As an example today I peeled the area around the exhaust that was about 18" wide by maybe 16" high. Took maybe 5 minutes to peel the glass and easily a half hour or more to grind the remaining resin off to get to the end grain balsa (this was more time than I have had to spend on the lower hull for a similar sized area). I have found that it is important to get all of the resin off of the area you are working or the drying is uneven. The second correction is that I have now found areas that are much more resistant to drying and have taken several days and the use of heat to get fully dry.

One other sort of weird thing I need to figure out is that some of the areas that I have applied the epoxy fairing to are now reading higher moisture content than the bare balsa below the spot being checked. I have to believe that is something to do with how these meters work with various materials. The levels are still ok, but higher than what I started with before fairing. Understanding this may take some communication with Electrophysics.

I wanted to show a couple more images of the after exterior skin removal and then the two stages of cleaning the end grain balsa up. The first image is just after shearing the skin off. You can clearly see the loose fibers of the chop strand mat. The next relatively easy step is just cleaning these strands up. That is followed by some determined grinding of the resin away from the end grain of the balsa. In the second image you can see the two colors and the light part has had the polyester resin fully ground away and the darker area is still in need of attention.





This area on the starboard bow also had several areas that had been repaired. I'm not sure if they were repairing blisters or some other kind of damage, but what is interesting is that I am pretty sure the area was repaired using fiberglass cloth and epoxy resin. The reason that this is notable is that the skin in these areas did not shear well at all and the grinding to get to the balsa was much more intense. One small bit of balsa actually pulled away with the outer skin, showing that the bond to the repair was stronger than the bond to the inner skin. The skin in these repair areas was far stiffer than the surrounding areas too. Another note is that the skin or lay up schedule in the bow is thicker than back in the waist or stern of the boat, which makes sense to me.

The balsa under the repairs was wet, so even if they had replaced the balsa in a local area, the rest of hull was still wet and then slowly soaked the repair balsa that is if it was actually ever replaced. Just fixing the local blister(s) didn't solve the wet balsa problem.