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Moisture Meters

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I was talking to a boat broker in So Cal this weekend about a boat we were interested in and was talking about a survey because wet decks were an known issue with this boat. He was telling me that the surveyors in California don't use moisture meters anymore as they were too unreliable and tapping was way more effective. I sold a J boat 10 years ago that the surveyor said he had high readings in the transom. We drilled a few core samples from the inside and they were all bone dry. So I  know they are not foolproof but are surveyors in Cal. not using moisture meters or is the broker blowing smoke?

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I am a Certified Marine Surveyor in So Cal.  I use an Electrophysics GRP 33 moisture meter.

It is not foolproof as you point out, but it is a valuable tool in my bag along with my IR camera, mallet, ears, eyes, multimeter, screwdrivers, socket set etc, etc.

Would love to know who the broker is.

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As HH says, they're valid tools, but (IMO) only within the right context.

I think the place people go off the rails is when they think the number "mean something".  That a reading of 38% is a problem but 32% is okay, or whatever.   Like a Loos gauge for rigging, the numbers are useful for identifying differences, but the quantitative readings aren't really meaningful as absolute load values.

The surveyors I know who use them, use them as a relative indicator.... as in "hmmm, the reading in this part of the deck is significantly higher, so let's look a little more closely at that spot to see IF there is a problem."  That's where the eyes, ears, mallet, etc come into play... to determine whether the anomalous reading is moisture in the panel, a difference in construction, a prior repair, or any of a number of other things. 

YMMV

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A moisture meter is only as good as the person using it.  A good surveyor will use it as one of a number of tools to properly assess the condition of a vessel not as the end all tool to find problems.

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These two shots show comparative readings of the port and starboard side decks on a small ULDB adjacent the chainplates.  The port side warranted further investigation.

 

Estbdside.JPG

Eportside.JPG

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On the other end is this Carbon Fiber mid size racer. A moisture meter could not be used here due to the conductive nature of Carbon.  The blistering was an indicator something was not right and the the trusty mallet and hearing confirmed it. This and other areas found in survey were subsequently repaired.

IMG_3516.jpg

IMG_0839.JPG

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To steal a line from golf; it’s not the wand, it’s the magician.

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17 hours ago, Hitchhiker said:

These two shots show comparative readings of the port and starboard side decks on a small ULDB adjacent the chainplates.  The port side warranted further investigation.

 

Estbdside.JPG

Eportside.JPG

Not unusual in that area as it's at the chainplates. Any load on the standing rigging over the years they move. The caulking has gotten dry too so some moisture ingress isn't uncommon. Also, I'm going to say that it's 79's or 80's C&C/Tartan or? It's pretty silly to condemn the boat just for that. Probably a quality/overbuilt boat in the first place. If that's the only issue I'd call it good. With the surveyor sounding it with a hammer in that area should show up if it is really an issue or not. In our area it's hard to test properly anyway. If you did something with this it would be ridiculous to have it done commercially at shipyard/shipwright rates. Probably do as much damage trying to fix it yourself. 

Sorry - what ULDB? I missed that.      

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@Maxx Baqustae. Why is it difficult to test in your area?

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4 hours ago, woahboy said:

@Maxx Baqustae. Why is it difficult to test in your area?

We live in a temperate rain forest most of the time. Some years it rains from November to June. Hardly a break. It has been my experience you need a few days of dry to do this properly. Most surveyors in the region (that are any good) recognize that. 

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When I bought the Electrophysics GRP 33 several years ago I was aware it was not to be relied on as the definitive test as to the presence of moisture under FRP.  The manufacturer provides a test plate and some fairly detailed instructions on how to calibrate and use the MM, which I follow religiously.

I use the MM followed up with tapping where the MM reads possible problems.  My untrained ear cannot separate marginal from obvious wet decks so I can't say how accurate the MM is but I will say when you tap that obvious problem the MM reads off the dial.  And when the MM reads dry, the tap sound is always very crisp. 

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Been through the moisture meter game in a respected yard after a haul that found hundreds of blisters on a 30 year old hull. After consultation which resulted in an $8,000 estimate to  power sand off 6 layers of antifouling and gel coat to bare fiberglass,  grind out the blisters,  let the hull dry for two months in hot weather with moisture meter monitoring, then fill the blisters with epoxy,  barrier coat the hull & apply an epoxy  copper paint (Trinidad SR).   Worked pretty good; 5 years later I'm facing a haul for paint rejuvenation this spring; divers claim some minor blisters which may be only paint. 

But anyway if your hull is wet,  gotta grind off all the bottom paint, start all over with a barrier coat, it's unavoidable.  Moisture meters are relative and only work away from metal so they're semi useless on decks near  shroud penetrations, etc.  Here's some photos to get the idea:
 

3.jpg

2.jpg

1.jpg

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35 minutes ago, axolotl said:

Been through the moisture meter game in a respected yard after a haul that found hundreds of blisters on a 30 year old hull. After consultation which resulted in an $8,000 estimate to  power sand off 6 layers of antifouling and gel coat to bare fiberglass,  grind out the blisters,  let the hull dry for two months in hot weather with moisture meter monitoring, then fill the blisters with epoxy,  barrier coat the hull & apply an epoxy  copper paint (Trinidad SR).   Worked pretty good; 5 years later I'm facing a haul for paint rejuvenation this spring; divers claim some minor blisters which may be only paint. 

But anyway if your hull is wet,  gotta grind off all the bottom paint, start all over with a barrier coat, it's unavoidable.  Moisture meters are relative and only work away from metal so they're semi useless on decks near  shroud penetrations, etc.  Here's some photos to get the idea:
 

3.jpg

2.jpg

1.jpg

Those pictures bring back memories of days under my former boat with the sudden acrid stench when the grinder broke into the blister.  Good times.

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It is common knowledge within the industry not to trust a brand new off the shelf moisture meter. They need to be calibrated specifically for wet boats. Generally a J/30 is used to determine a baseline of soaking wet core. The surveyor uses his experience to extrapolate  from there. If you have no access to a J/30 or balsa cored J boat then a wet sponge can be used in its place.

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^^ Hah, thats so true. Owning 2 TPI built J's means a Tramex should be standard equipment. But I find I can always find a new wet spot on my J/35 for field recalibration, no need to hunt down a 30.

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I'm going to leave these images here as they sort of go with the topic especially in regard to the available tools in a surveyors kit. I'm in the UK looking at a Carbon over Nomex honey comb boat.  Moisture meter is no good so I left it at home.  Infra Red imaging comes in useful in some areas though.  These two images are the outside and inside of the port side bow panel.  Kind of cool really. But, I could be geeking out!

image.jpeg

image.jpeg

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Has anyone used a typical wall density tester? Wet core has to be denser than dry core. You should easily see where solid blocking begins and ends around highload deck locations. If the deck is denser a foot around the shrouds then it probably has wet core. Other than drilling holes in the bottom of J boats... I have no experience with wet core. If one of those $30 Stanley ones works on a wall in your house. Why not in a composite panel of deck & hull?

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On 4/1/2019 at 8:31 PM, sierrawhiskeygolf said:

Looks to me like an Olson 30. 

Could be. But most of Santa Cruz ULDB's used that type of construction with holy rail as part of it. Might be a Wildy 30 too.

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I have a Tramex. Useful tool, to be used as part of a thorough examination and appraisal.

My wife uses it to give the firewood man a hard time....

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On 4/1/2019 at 8:31 PM, sierrawhiskeygolf said:

Looks to me like an Olson 30. 

Probably not.  O30 has a quite wide inward flange.   Below is what I believe to be a fairly stock O30.  Note how inboard the toe rails are compared to the ULDB in the photos above.

O30.jpg

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On 3/24/2019 at 1:14 PM, sledracr said:

The surveyors I know who use them, use them as a relative indicator.... as in "hmmm, the reading in this part of the deck is significantly higher, so let's look a little more closely at that spot to see IF there is a problem."  That's where the eyes, ears, mallet, etc come into play... to determine whether the anomalous reading is moisture in the panel, a difference in construction, a prior repair, or any of a number of other things. 

That's the way I see them, at least in the right climate. They're sorta useful and so is a mallet.

If you really want to know the condition of core material, use a drill.

I watched a good surveyor use his moisture meter and hammer on the transom of a friend's boat. It tested dry and sounded as solid as granite.

Then we got out the drill and black core soup came out.

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On 4/3/2019 at 6:56 PM, 12 metre said:

Probably not.  O30 has a quite wide inward flange.   Below is what I believe to be a fairly stock O30.  Note how inboard the toe rails are compared to the ULDB in the photos above.

You are correct! I noticed another difference - the socketed stanchion in the original pic is like O30 but the pictured one is inside the toe rail, O30 outside. 

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On 4/3/2019 at 1:06 PM, Maxx Baqustae said:

Could be. But most of Santa Cruz ULDB's used that type of construction with holy rail as part of it. Might be a Wildy 30 too.

I'm guessing Moore 24. Not an Olson. Maybe a Wilderness 30, but I think the Wilderness has deck mounted stanchions and I recall those sockets on my two Moores, but it has been more than 25 years since I owned a Moore and age is taking its toll on my brain cells (among other things).

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On 4/12/2019 at 12:58 PM, msvphoto said:

I'm guessing Moore 24. Not an Olson. Maybe a Wilderness 30, but I think the Wilderness has deck mounted stanchions and I recall those sockets on my two Moores, but it has been more than 25 years since I owned a Moore and age is taking its toll on my brain cells (among other things).

Yup. Not an Olson. I had a Wildy from new. The two tone deck non skid is wrong a bit. Chuck Jones might weigh in.He's on my Wastebook page friends.

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Someone's going to get it.......... eventually!

Btw, the boat was not condemned!  That was a pretty silly sentence!

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On 4/14/2019 at 9:00 AM, Hitchhiker said:

Someone's going to get it.......... eventually!

Btw, the boat was not condemned!  That was a pretty silly sentence!

Express 27? 

Socketed stanchions, chain plate looks about the same, not a Moore, so that's my new guess.

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44 minutes ago, msvphoto said:

Express 27? 

Socketed stanchions, chain plate looks about the same, not a Moore, so that's my new guess.

Winner!

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