A moisture reading is a number somebody has to interpret. Here's what the meter can tell you, what it can't, and the one ask that protects you before you spend anything.
Stringers are the boat's floor joists. They run the length of the hull, they stiffen it, and on most boats this guide's readers are looking at, the engines bolt to them. In a lot of production boats they're plywood inside fiberglass, and plywood that stays wet loses strength slowly and invisibly.
The buying move costs you nothing to ask for: have the surveyor moisture-test the stringers and the hull core specifically, not only the decks. If the readings come back high, the next step is a structural evaluation, and the decision after that is yours.
Not usually through the hull itself. It gets in through penetrations. One owner on the public Meridian owners' forum described it exactly: his boat had been in the water a total of twelve months, wintered indoors, and the survey still found high moisture in the longitudinal stringers. The culprit was a shaft-collar thru-hull letting water reach the plywood, which then wicked along the stringers. The boat was nearly new. The path was one fitting.
Unsealed limber holes, thru-hull penetrations, and hardware bedding are the usual doors. That's why age alone tells you little here. A well-kept older boat can test dry, and a young boat with one bad fitting can test wet.
Marine surveyor David Pascoe wrote the plainest public explanation of this we know: a moisture meter used to detect wet cores beneath the outer skin on decks and stringers can produce reliable results, and the same meter can also mislead. Salt residue affects the readings. A meter placed over a void, a delamination, or resin-starved laminate can read dry while the material behind that spot is soaked.
So a single reading is neither a pass nor a kill. It's an instrument reading that needs a person who knows the instrument, taken in more than one place, interpreted next to what the surveyor's eyes and hammer say. When a report hands you numbers with no interpretation, the numbers are still questions.
Word for word, to your surveyor: "Please moisture-test the stringers and the hull core, not just the decks." It's a normal request. A surveyor who bristles at it has told you something too.
If the readings come back high, ask for a structural read: is this cosmetic moisture in a non-structural area, or is it in the wood the engines sit on? Walk, renegotiate, or repair is your call to make after that answer, and this page won't make it for you.
Wet core used to mean cutting the structure open. There is now at least one company whose entire business is drying wet core in place, and its own pitch is aimed at exactly this moment: a failed survey. It advertises the repair as non-invasive and, by its own published claim, substantially cheaper than traditional tear-out. Surveyors have been pointing buyers at in-place drying as an alternative for over a decade, as a public Trawler Forum thread from 2014 shows.
Repair existing is not the same as repair needed. What it means for a buyer is that a high reading opens a negotiation instead of ending one.
Any boat with wood-cored stringers or a cored hull, which covers a large share of the production boats Loopers actually buy. One more honest signal worth knowing: some owner communities discuss moisture findings completely in the open, on public forums, with real survey numbers and real fixes. When you're researching a model, finding that kind of open conversation is a good sign about the community you'd be joining, and it's exactly the kind of source we look for.
We haven't put a moisture meter on anyone's stringers. What we hold on specific models is marked for how well it can be backed, and where all we have is somebody's word, the page says so. This guide gives you the question to ask and the way to read the answer. The survey is still the survey.
If we've got something wrong, tell us and we'll fix it — support@caniloop.net. A correction from someone who has actually run it is worth more than anything we can write.