Water intrusion or scale confusion?

To the editor: I recently read Steve D’Antonio’s excellent piece on coring (Getting to the core Issue 146 May/June 2005). I wonder if some words of wisdom are available? I live on a 33-foot amateur-built boat (built in 1984 in France) with a balsa-cored hull. The last time I had the boat hauled for bottom painting, I was very surprised to find out that the Travelift scale showed 10 tons. The original papers state a displacement of 8 tons, and I doubt we carry 2 tons of stuff.

We have traveled extensively, and the boat is currently in Brazil.

Would drilling small holes on the inside skin in different places give me an idea of how much water is there, or are there other ways?

– Luis Salcedo is a retired doctor from Rio de Janeiro, Brazil, who has sailed his 33-foot sloop in the Caribbean and the east coast of South America.

Contributing Editor Steve C. D’Antonio responds: Unless they have been calibrated recently, I wouldn’t put too much stock in Travelift scales, they are usually wildly inaccurate. An error factor of 25 percent isn’t unusual. If, however, your waterline is disappearing, you may actually have a problem. If the core were this saturated, it’s hard to believe you wouldn’t have other signs, such as brown water leaking from any penetration in the inside of the hull, even the smallest screw hole.

If you have no other and want to drill a few test holes carefully, you can do this, or better still, find a surveyor with a moisture meter (ensure that he knows how to use it) and have him test the inside of the hull both above and below the waterline, preferably while the boat is out of the water. If the boat is in the water, the meter may read the water on the outside of the hull, below the waterline, depending on the thickness of the core. If the hull is saturated, it will most likely be wet above the waterline as well, and the meter, or test holes, will indicate this clearly.

By Ocean Navigator