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Old 10-02-2012, 09:46 AM   #20
RickB
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
Posts: 3,804
I'll side with Mr. Psneeld ... moisture meters have become the talisman of silver hammer surveyors and continue to impress the villagers with their electronic wizardry. No doubt someday they will be consigned to the shelves alongside the Heidelberg electric belt.

Moisture meters were developed for wood and grain and have a good history of reasonable accuracy in those applications, reasonable for field use anyway. But thre is a world of difference between FRP and wood or grain. A quick review of the literature on marine moisture measurement shows it to be almost exclusively written by those who sell the units and surveyors who sell the use of them.

Thermal imaging offers what may be the best chance to identify areas of delamination or moisture intrusion and we use it when we suspect problems on FRP hulls. Even then there is considerable "art" involved in the process with regard to internal and external temperature gradients and environmental conditions such as air temperature, sunlight and shadow.

Ultrasonic testing is routine and we use it for thickness gauging of metallic hull plating and piping. I use a small unit when I suspect problems and if something shows up I call in a class approved surveyor to confirm and document the condition. Using ultrasonics to survey an FRP hull requires a specialized device and more training than the normal small boat surveyor has at his disposal.

Anything by an alphabet surveyor beyond an hour or two spent tap tap tapping on the hull is (in my opinion) nothing more than show. Even the legitimate class surveyors(ABS, Lloyd's, DNV, etc.) call in specialist NDTcontractors when a potential problem area is suspected.
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