How should I interpret these moisture readings?
 

Hi everyone, new member here. I am considering buying a 1995 Baja 272 but I have concerns about moister in the transom, stringers, ect. The boat is in good enough shape and cosmetically seen better days, but overall acceptable to me as its going to be a long term project. I had it surveyed and everything came back as expected except the surveyor found elevated moisture levels in some spots on the transom and the aft section of the stringers using his moisture meter (General Tools MMD7). The readings taken from the transom read in the 40 - 72% range and the reading from the stringers in the aft section read from 60 - 84%. The boat is stored outside on a trailer and he said there were signs that there had been standing water in the bilge. He also told me that he sounded everything with a hammer and it sounded solid but he wouldn't trust it due to the elevated readings he got on his meter. I have been doing some research and from what I have gathered, moisture meter readings can be hit or miss and there are lots of variables that can affect their accuracy. I know the best way to check for moisture is by drilling into the suspected areas and looking at the wood shavings but it can be difficult to get someone to let you drill holes in their boat. Would you trust a moisture meter over sounding with a hammer?

you need to use a marine moisture meter and someone that knows how to check with a small hammer

You should assume the worst and budget accordingly. Water standing in bilge means transom was likely soaking up water at least the thru holes where the transom assemblies mount. I'd be surprised if they glassed that in.

Normal moisture reading in wood is anything 15% and below. Plywood starts to rot a 21%. Any water in the bilge will give you a false reading. A hammer in conjunction with the tester is best. Good luck.

I have that meter. It's non invasive correct? No pins or holes drilled, just lay it on the outside of the transosm?
The meter has several settings for different hardness and material. None of them say fiberglass.
With mine on the setting that gives the lowest reading I get from 0 to 14% moving around the transom. Don/t know how accurate this is since it is a cheap moisture meter, but I plan to use my readings as a base line to watch for change.
If he is on the least sensitive setting and getting 50% and more I would be nervous.
Surprised a professional surveyor doesn't have a more expensive meter.
Good luck.

I was going to say the same.

I was surprised as well.

I used to run a company that manufactured hardwood tent pins for the Department of Defense. Like all things government there was pages and pages of specs. When finished these tent pins were a work of art. I can't remember the exact moisture spec but it was pretty much the same as for hardwood furniture . Based on my experience of sampling and testing semis full of hardwood... I do not see how you can moisture test a wood transom without penetrating the fiberglass and the wood. We tested by slamming the two sharply pointed probes into the wood as hard as we good. Then took a reading.

Padraig

Speicher Lane's article aligns with what I have read a lot about. Pretty much anything can affect how these things read. The bilge was a bit dirty when he was taking these readings, possibly moisture in the grime could have affected the readings. I think I might need to go over myself and start hammering on things.