Reality of high moisture readings

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RedRascal

Senior Member
Joined
Dec 27, 2019
Messages
391
Location
USA
Vessel Name
Rascal
Vessel Make
Homemade
I've been looking at CHB and Grand Banks flavor of Taiwanese boats and have questions about moisture meter readings. I decided to invest in a $40 Klein moisture meter to help me find potential spots where moisture damage would be likely. The boats I am looking at are in the rainy Pacific Northwest so any of these older trawlers that have been stored outside usually have issues with the deck core being wet. I figure it's a given that anything I get will most likely need the deck ripped off, core repaired and re-glassed. What I would like to avoid are rot issues in the house structure since I view that as more fiddly to remediate especially on top of doing deck work.

So when I get 35% or 50%+ moisture readings around the interior windows or aft cabin bulkheads those are the areas where I have some questions. If I am not seeing water stains on the inside and the wood seems solid(no delamination) is it realistic that this wood can could dry out once leaks are stopped? Wood at this level would have been like this for many months if not years unless it got baked dry in the summer.

I am curious if someone else has had any luck "drying out" a boat with a combination of heat, dehumidifiers and lots of airflow. Also I am not pro with a moisture meter, I've just checked my buddy's CHB that is stored undercover as a baseline. I have to imagine I am making some mistakes with it but generally I believe it's helping find some wet spots.
 
You did not say what vintage. My previous GB36 a 1971 had glass over fiberglass roof. The teak decks were bedded in something There was Zero leaks under the roof or decks. The only source of leaks were in the walls from the window troughs especially when the drain holes were plugged was very often. Solved that with Captain Tolly, lots of it until it no longer leaked. Yes I did remove some wall wood rot and some aft canin roof rot where previous owners cut out holes for chimney vents. Hope this helps.
 
Looking at the late 70s into the 80s. Shooting for a glass house vs. glass over plywood. Windows are definitely a weak spot. If the boats live outside the dry ones are tough to find.
 
Looking at the late 70s into the 80s. Shooting for a glass house vs. glass over plywood. Windows are definitely a weak spot. If the boats live outside the dry ones are tough to find.
I'm on my 3rd boat of that vintage. The first two, a 76 Tolly then an 83 Californian. Both were glass over ply houses. Current boat is an 86 West Bay. I think it too is glass over ply construction. But I haven't taken anything out yet to prove that. It may be difficult to find a boat from the 70's to 80's with a glass house.
 
If it is glass over ply, it will dry eventually if kept dehumidified. It will take months. It will not repair any damage already done. If the construction is a glass-ply-glass sandwich, then drying it is a major undertaking, if it is possible at all.
 
Is this a meter with pins? Also, are you trying to get a reading from wood only? If you are trying to get a reading through fiberglass it's probably wrong. If you are reading directly into wood you may get a close reading. And, cheap meters are just that...cheap. Try it in a controlled environment (your house) and try to get a baseline.
 
Certainly any moisture meter - even expensive ones (I have the $600 Tramex) - requires a great deal of interpretation. That means trying it on known samples until you understand what the readings mean.
 
I am definitely on the bottom end of the learning curve. The moisture meter I am using is pinless. I do have a buddy with a CHB 34 that has been in covered moorage for decades. I've gone all over his boat getting readings and they are all low except for a known section on the aft deck that gets some rain when the wind is blowing. It has a known leak at that spot. When I look at boats that have been stored outdoors the readings usually comeback much higher in places where leaks are common. It's difficult to determine if the readings are suggesting material problems or not. This era of boats are know to have rot issues in the decks and around the windows so I am cautious. Plywood sandwiched in the house structure between glass is what makes me the most nervous since it won't dry. It's a fine balance of trying to rule out project boats on my own vs. giving a boat a thumbs up that I want to take to survey. I am pretty sure it will be difficult to find a totally dry boat so I see a dehumidifier in my future.

Another member sent me a link to this post which was a great read Moisture Meter Mythology and Flir thermal imager
 
There is a product called Inject-A-Deck that works very well to repair decks without cutting them apart. I have done it both ways and much prefer the Inject-A- Deck method.
 

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