So I tore off the laminate and tested the interior of the plug. Higher than the exposed wood, but still way down from the original 37%. It is kind of amazing how fast balsa can dry out. A stick of red alder, which I use for smoking salmon, would take several months to dry out like this.

Here is the extent of the removed balsa. You can see by the strips at the upper right how much I was expanding with each cut. The moisture was mostly against the lower laminate and when I no longer found structurally compromised wood, I stopped. Well, first I drilled some outlying holes to examine and, since they were okay, I stopped. I decided not to remove the core to the black hole at the top of the picture because the wood in between it and my major area was okay even though wet. The moisture reading in the wood was 37%, which is basically saturated but not dripping wet.

And the edge of the balsa still in the boat is only down 10% (in the first 2 mm). A long way to go. I'm thinking months in a heated garage while applying heating pads and heat lamps. That's not practical for most boat owners.

I am still a long way off from what my replacement balsa shows. And I am forced to guess how the balsa is drying out between the laminates where I can't get a reading with this meter.

So I tore off the laminate and tested the interior of the plug. Higher than the exposed wood, but still way down from the original 37%. It is kind of amazing how fast balsa can dry out. A stick of red alder, which I use for smoking salmon, would take several months to dry out like this.

When I drilled out the deck fill for the gas tank, the moisture level (in the deck) was at 37% because of leaking bow pulpit and cleats. Five days later when I rechecked the moisture in the plug, it was down to 18%. But I know this one. It's only down to 18 on the surface (or as deep as my sensor pins penetrate.)

Here is the scariest part. This is looking towards the center of the boat once all of the balsa was cleaned out of the initial section. Even though the wood is showing less damage overall, there is a spot of wet rotted wood that is basically forming a tunnel against the outer skin of the hull. Water in this area can be pumped into other areas by the hull pounding. I found the adhesion to be very good, so I'm hoping this doesn't go far. But the cutout has to be expanded until I find the end of the damage. I made quite a few cuts, expanding by about an inch at a time, which is the amount that my vibrating saw could easily remove.

Using the cut off tool shown in the prior picture, the rotten balsa was removed so that I could see where I should concentrate my next expansion of the opening. This also shows why the rotten core wasn't revealed when I surveyed the boat. The upper area of this wood is good in many places. The rot is patchy and does not reveal itself readily when using the "bonk with a hammer" test. The resin is drawn up into the kerfs in the balsa by capillary action, forming a resin lattice that helps masks a rotten core. Much of this area was only wet/rotten on the bottom.

M

So I tore off the laminate and tested the interior of the plug. Higher than the exposed wood, but still way down from the original 37%. It is kind of amazing how fast balsa can dry out. A stick of red alder, which I use for smoking salmon, would take several months to dry out like this.

Marco Flamingo
Oct 5, 2015

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