Using Moisture Meters
Surveying Fiberglass Power Boats
by David Pascoe
Moisture meters are one of the most valuable tools in the surveyor's kit, but only if he knows how to use it properly.
These instruments have been in use for at least a decade now but surprisingly almost no information has been published about these devices.
In order to settle some of the common questions about their use the author set about testing meters on a variety of materials and under varying circumstances.
What are the strengths and weaknesses of these instruments? Are the meters completely reliable or are they capable of giving false readings? Are they affected by temperature and humidity? Do they read deep into the laminate and, if so, how deep? And finally, how well do meters perform in conjunction with cores.
The critical question concerning cores is: Where is the water that the meter is detecting?
With a cored laminate we have two skins and a core, but we also know that the outer skin is likely to have absorbed water that will trigger a high meter reading.
Because of this, we are faced with the question of whether it is the outer skin that is wet, the core, or perhaps both.
Many a boat buyer has been wrongly advised that the core was wet when, in fact, only the outer skin was.
These are only a few of the questions that need answering. However, I was further motivated when I learned that Sea Ray Boats, in conjunction with their core failure problems, was aggressively challenging surveyor's use of meters on hulls with saturated cores.
Indeed, that boat company had actually issued a bulletin to their dealers claiming that meters are not accurate and that surveyors were misusing them ? without saying how. These allegations ultimately proved false.
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Table of Contents: Chapter 7
7. Using Moisture Meters 173
What does a meter really detect? 176
Are meters affected by humidity? 176
Do Meters read fluids other than water? 176
Does old gel coat absorb high amounts of water? 176
Water Absorption by Solid Laminates 177
Reinforcement Fabrics 181
Rot in Balsa 186
Hydraulic Destruction of Balsa 187
Foam Cores 187
Meter Behavior With Foam Bottoms 190
Meter Behavior with Foam Hull Sides 191
Pseudo Cores 191
Spray Cores 192
Bottom Paint 193
Decks and Housetops 193
- 2nd Edition
by David H. Pascoe
Publisher: D. H. Pascoe & Co., Inc.
David Pascoe - Biography
David Pascoe is a second generation marine surveyor in his family who began his surveying career at age 16 as an apprentice in 1965 as the era of wooden boats was drawing to a close.
Certified by the National Association of Marine Surveyors in 1972, he has conducted over 5,000 pre purchase surveys in addition to having conducted hundreds of boating accident investigations, including fires, sinkings, hull failures and machinery failure analysis.
Over forty years of knowledge and experience are brought to bear in following books. David Pascoe is the author of:
- "Mid Size Power Boats" (2003)
- "Buyers’ Guide to Outboard Boats" (2002)
- "Surveying Fiberglass Power Boats" (2001, 2nd Edition - 2005)
- "Marine Investigations" (2004).
In addition to readers in the United States, boaters and boat industry professionals worldwide from over 70 countries have purchased David Pascoe's books, since introduction of his first book in 2001.
In 2012, David Pascoe has retired from marine surveying business at age 65.
On November 23rd, 2018, David Pascoe has passed away at age 71.