Recently found a buyer for our boat (1984 H31) but on survey it was found to have high moisture readings in some areas (100%)! She has no history of blisters, had bottom barrier coated about 7 years ago. Have been careful to maintain keel/hull joint and had keel bolts checked a few years ago. There was a small amount of moisture visible at the very front of the hull/keel joint when she was hauled,we did not work on it this year as the crack was very small. To investigate we had three patches ground off where readings were high thinking that water may have been trapped under bottom paint but still tested high. She was only launched and in the water for about 2 weeks before she was hauled for survey and on the hard for about 5 days before inspection. The had a plug drilled out by the over enthusiastic "fiberglass guy who said he was very puzzled. It was sent for testing - no result from the lab yet. Inside the moisture readings on the hull bottom were high but patchy also under the port settee low down. It did occur to me that there could be water trapped between the liner and hull. We have always been careful to keep the bilge dry and not use the shower but have had some incidents in the past,water tank overflows mainly. Has anyone else had similar problems? Does anyone have any ideas? Thanks for your help on this one.
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Tim
Moisture content
I saw a boat which read 100% moisture content. When we drilled the hull we found a DRY core, dry glass, dry everything. We tested the meter on other boats, which all showed very low, or no, moisture. It's puzzling, but moisture content meters are not always accurate.
I saw a boat which read 100% moisture content. When we drilled the hull we found a DRY core, dry glass, dry everything. We tested the meter on other boats, which all showed very low, or no, moisture. It's puzzling, but moisture content meters are not always accurate.
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Warren M.
Moisture readings
Reading the results of moisture meters is more an artform than a science. The fact that the surveyor got some 100% readings sounds odd to me, particularly since there was no obvious evidence of moisture in these areas. I would suggest getting a number of additional readings by other experts using different moisture meters. Also, on some boats like my H28.5, water (from the shower, stuffing box, etc.) is easily trapped under the cabin sole that sometimes makes its way to the bilge via the stringers, sometimes not. You may want to investigate your boat's innards to see if this could be the cause of the high readings. Good luck and keep us posted on the results of the core sample.
Reading the results of moisture meters is more an artform than a science. The fact that the surveyor got some 100% readings sounds odd to me, particularly since there was no obvious evidence of moisture in these areas. I would suggest getting a number of additional readings by other experts using different moisture meters. Also, on some boats like my H28.5, water (from the shower, stuffing box, etc.) is easily trapped under the cabin sole that sometimes makes its way to the bilge via the stringers, sometimes not. You may want to investigate your boat's innards to see if this could be the cause of the high readings. Good luck and keep us posted on the results of the core sample.
100% moisture is not possible
It just illustrates the foolish thinking of the maker (and user) of the test equipment. There are basically two methods of measuring moisture that I know of - resistance and capacitance (or is it inductance?). The resistance method is faulty in that it will vary widely depending on whether the moisture is salty (less resistance) or not. It may also vary depending on how the contact points are applied. It will also vary depending on the material - ie: wood or fiberglass. The capacitance method is affected by other factors like metal parts nearby or additives to paint or resin. In short, neither method is foolproof. Either method will serve as proof for fools. Get a new surveyer!
It just illustrates the foolish thinking of the maker (and user) of the test equipment. There are basically two methods of measuring moisture that I know of - resistance and capacitance (or is it inductance?). The resistance method is faulty in that it will vary widely depending on whether the moisture is salty (less resistance) or not. It may also vary depending on how the contact points are applied. It will also vary depending on the material - ie: wood or fiberglass. The capacitance method is affected by other factors like metal parts nearby or additives to paint or resin. In short, neither method is foolproof. Either method will serve as proof for fools. Get a new surveyer!
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Catpn Dare
moisture meters
Generally, a sensible way to use a moisture meter is to take readings a foot or so above the waterline and then compare it to readings taken below the water line. I've seen people swear there was a problem only to fine they were reading through the fiberglass and picking up water in the bilge or picking up the tanks themselves. Certain types of bottom paint (Baltiplate for instance) can cause an erroneous reading.
Generally, a sensible way to use a moisture meter is to take readings a foot or so above the waterline and then compare it to readings taken below the water line. I've seen people swear there was a problem only to fine they were reading through the fiberglass and picking up water in the bilge or picking up the tanks themselves. Certain types of bottom paint (Baltiplate for instance) can cause an erroneous reading.
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Dave
Test results back
Just got test results back from Structural Composites Inc. in FL Astm D 4442 test shows moisture content 87% (dry basis) 86% (wet basis)on sample of the core drilled out of the bottom of the boat right above the keel at the back end of the bilge.
Just got test results back from Structural Composites Inc. in FL Astm D 4442 test shows moisture content 87% (dry basis) 86% (wet basis)on sample of the core drilled out of the bottom of the boat right above the keel at the back end of the bilge.
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