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.)

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.

Here is what removing the top laminate revealed after I cut it off with a little circular saw. There is a rotten area right in the center caused by several leaking pop rivets right at the aft corner of the seat box. What I had suspected is that the leak migrated towards the center of the boat. You can see that balsa does not rot uniformly, meaning that some pieces in the parquet have rotted while others simply discolored. The dark rectangle on the right side of the cutout was completely saturated and rotten while some of the surrounding wood was almost dry. To the left of the cutout is another dark hole that was bad. I will have to expand the cutout to include that area.

M

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.)

Marco Flamingo
Oct 5, 2015

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