Electrophysics moisture reading on the hull

[phorvati]

Clear evidence that bottom paint can give misleading moisture readings. My entire bottom is pegging like crazy when readings are taken on the outside. From the inside, hull is drying up very well. So I thought in few spots, I'd scrape the many layers of bottom paint from various POs left. And low and behold, it looks much better when Reading is taken against epoxy barrier coat. That grey stuff is most likely interlux 2000.

[boatpoker]

See Moisture Meter Mythology

[lateral]

1.01Moisture meters (radio frequency) gives incorrect readings where there is metal, metal salts in scan path. Metal oxide/salts in paints.
Still a very useful tool.

[phorvati]

Originally Posted by lateral

1.01Moisture meters (radio frequency) gives incorrect readings where there is metal, metal salts in scan path. Metal oxide/salts in paints.
Still a very useful tool.

No doubt. In the hands of an impatient novice its a useless tool . But if you have the patience and diligence to understand how it works and use it properly, its a good tool. However, in my case, 5 layers of bottom paint are completely masking the true state of the hull. The entire bottom is pegging. So I am getting readings on the inside which are more useful. But even that is not without pain. If surface is not perfectly smooth, for instance, PO's bilge paint runs, it causes CT-33 to give low reading where its actually picking up air in portion of the sensor plate. So in reality i would have to sand the bilge paint runs to get a reading. For outside, I was able to get more meaningful readings using the cheap Home Depot moisture meter that costs 30$.