Updated October 26, 2026
How surveys describe it
Wording varies by surveyor. Illustrative examples (not quoted from any real survey):
- “Elevated moisture readings were noted in the deck around the bow cleat.”
- “Delamination was found in the cockpit sole; recommend further investigation.”
What it is
Many fiberglass decks are a sandwich: two fiberglass skins around a core of balsa or foam. When water gets past a fitting's sealant it can soak the core, which can rot or lose its bond to the skins (delamination). A surveyor finds it with a moisture meter and by tapping (sounding) for a dull note.
How serious it is
It depends on how big the wet area is and whether it's spreading. A few small wet spots around hardware are common and fixable; a large soft deck is a major repair. Moisture meters give relative readings, not a percentage of water, so a reading is a reason to investigate rather than a diagnosis.[1]
In our reports this usually lands under Negotiate. Your survey's details decide.
What it typically costs
| Scope | Estimated range |
|---|---|
| Typical job | $1,500–$15,000 |
These are whole-job ranges drawn from published figures.[2][3]
- Cut out, dry or replace core, re-glass and refinish
- Small areas around hardware sit at the low end; several areas or one large area move toward the top
- A moisture reading alone doesn't prove wet core: a yard may sound or core-sample it first
Estimates to help you frame a conversation with a yard, not quotes. Real prices depend on the boat, the yard, access and what's found once work starts. Confirm with your surveyor or a qualified yard.
What to ask your surveyor or yard
- How large is the wet area, and how high were the readings compared with dry areas nearby?
- Did the deck feel soft or sound dull when tapped?
- Should a yard sound or core-sample it before closing?
- Is the source a fitting that's still leaking?
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Get a free previewSources
- Moisture Meters: Can You Trust Them? We Test Five Models, Practical Sailor. Boating publication. Accessed 2026-10-26.
- Deck repair budget, The Hull Truth forums (owner reports). Boat owners' reported prices. Accessed 2026-10-26.
- Hidden Defects in Used Boats: What Marine Surveyors Check, MarineInspection.app. Boating publication. Accessed 2026-10-26.