The Usefulness of Moisture Meters

[Sea Hunt]

In my recent search for a marine surveyor in the New Jersey area I talked with one surveyor who told me something I found surprising.

In past contacts with surveyors, they have always said they perform a moisture test on the hull as part of the survey, some even saying they do so with a special moisture meter instead of a small plastic hammer. Each surveyor had known that the sailboat was in the water, had been in the water for some time, and would be hauled out of the water specifically for the marine survey.

Today I spoke with a marine surveyor who told me he would NOT perform a moisture test on the sailboat that I MAY be interested in because it will have been in the water for several weeks at the time of inspection and thus he cannot do a valid moisture inspection with a meter. He said the sailboat would have to sit on the hard for a minimum of 7 days before a moisture meter inspection could be done.

I found this statement contrary to what I understood every other surveyor had told me. All the others said they would be able to do a moisture meter test shortly after haul out.

Being the dummy that I am I went immediately to my "bible", that is, Inspecting the Aging Sailboat by Don Casey. I have read this book several times yet to my surprise I found the following statements at page 17 in a discussion of "moisture meters":

". . . moisture meters tell you very little about the interior of the laminate"

"On a boat that has been out of the water for several weeks, a reading around 5 percent suggests the hull is dry."

From the above I am assuming Mr. Casey is saying that if you want to use a moisture meter to determine moisture in the hull, if any, you need to have the boat out of the water for more than a week at a minimum.

What is the collective wisdom on this board about moisture meters Do they provide any useful information if the boat is hauled out shortly before the survey

I am guessing there is a simple explanation for my confusion. At least I hope so.

Also, as an aside, of all the marine surveyors I have spoken with in the past week not one said the survey would include going up the mast to inspect the mast. A few said "I can recommend a rigger to you but I do not climb the mast." Is this a new policy among surveyors or just an effort to get work for their rigger friends

[WaywardWind]

Today I spoke with a marine surveyor who told me he would NOT perform a moisture test ...

(Don Casey said) ". . . moisture meters tell you very little about the interior of the laminate"

"Moisture meters" are the divining rods, the tea leaves, the monkeys' entrails, the "eye of newt" of the fringe element of the Marine Surveyor business.

The Margin Of Error on a "moisture meter" is SO great, you might as well ask your favorite bookie's opinion.

A "moisture meter" will give a PRECISE measurement to less than 1%

...... but ......

....... a measurement ACCURATE (there IS a difference) to two digits to the LEFT of the decimal point.

Some people are comfortable with precision, others far more comfortable with accuracy. The second group ignores "moisture meter" readings. The sound of the non-business end of a screwdriver tapped against the hull is more useful.

[Russell]

I actually agree with WW on this one, moisture meters are basicly voodoo. Especially on a freshly hauled boat, bottom paint holds a lot of moisture for awhile. They wont tell you much useful. CDs are all solid fiberglass boats anyway, its not like you have a cored hull to worry about (the moisture meter may be a bit handy on the deck though in areas of concern). Blisters will be obvious on a freshly hauled boat (or bad blisters on a dry boat), you dont need a moisture meter to tell you about them. The rudder is cored, and you are 100% garunteed to get a higher moisture reading there then on the hull, but what does that actually tell you? Not much other then inciting unneeded worry. Unless you are talking total core saturation, I dont think the meter will tell you much, and at that point the plastic mallet would reveal the issue anyway.

The last haulout I did was at a yard where I was very close to the yard owner. I had full run of the shop and permission to use any tool on premisis (he had little respect for his insurance company rules, or any rules for that matter). Among these were 3 moisture meters, all of different types and top of the line. I was hauled out for a few weeks and played around with the meters every day and read everything i could find out about them. The yard owner also explained everything he knew of them, and due to an issue I had with some bottom paint an interlux employee came to inspect my bottom, and I discussed them with him as well. Granted all this does not come close to adding up to what a surveyor with years of experience with them understands, but I think I learned a lot none the less.

A surveyor being straitforward about the moisture meter I think is actually a good sign regarding the surveyor. I would give him + points in your selection process because of it.

Because CDs are solid glass hulls with a good reputation I would be very suprised if you found any serious issues below the waterline. I have never heard of any issues with CD hulls. Sure blisters, they are 20+ year old boats, but blisters shouldnt be a deal breaker on a good boat. But delamination in a CD hull? I would be shocked. Unless the boat comes out of the water with hundreds of blisters, dont worry about it. Heck I bought a Catalina 30 that DID come out of the water with hundreds of blisters, I got it for a steal because of it, sail it a couple years and sold it for more then I bought it for. But I would never expect that on a CD. Anyway, point being, on a good quality hull the moisture meter voodoo debate is rather pointless anyway. But I know you have concerns about soggy balsa decks, and here a moisture meter I think will be somewhat useful and no doubt this surveyor would use it there.

I know we have one certain CD33 owner on these boards who is a surveyor, I am hoping he chimes in with his opinions on moisture meter matter, this is a subject we all could probably stand to learn more about.

[Russell]

Also, as an aside, of all the marine surveyors I have spoken with in the past week not one said the survey would include going up the mast to inspect the mast. A few said "I can recommend a rigger to you but I do not climb the mast." Is this a new policy among surveyors or just an effort to get work for their rigger friends

Sorry, I got on the moisture meter tangent and forgot to respond to this. Most surveyors do not go up the rig, that is why I made special mention of the surveyor I recommended to you in the PM I sent in that she does go up the rig. Hiring a rigger to do a rig survey is an option and not expensive, BUT keep in mind riggers doing a survey are doing it in the hopes of gaining your buisness to replace and repair, they are not totally impartial like your hull surveyor. This is why a rig survey is rather inexpensive (maybe $100 to $150).

If you cant get a surveyor who goes up the rig though, then hiring a rig surveyor isnt a bad idea, but when they tell you "the rig is 10 years old and it all should be replaced now", dont freak out, focus instead on they specific areas of high concern.

[Maine Sail]

You found a good and honest surveyor. Is the boat cored? If not then measuring moisture in the hull is a lot tougher to do well than a deck is as paint needs to be removed and the hull should have been dried out for more than just a few days..

Some surveyors are disreputable the same as yards who haul a boat and apply a barrier coat within a week of it being hauled. It is this percentage of surveyors who can give an industry a bad rap. On the other hand we have a few "high profile" surveyors who use scare tactics when discussing MM to scare off anyone but a surveyor from using them. These surveyors want your money and don't want you to use or own a meter because it could prevent them from garnering a lot of business.

MM are great tools but sadly some surveyors do not have a good grasp on how to use them and even if they do they still sometimes use them incorrectly so you feel like you got your "money's worth".

As one who uses both soundings and MM readings they both often need to be used together. Wet core often sounds out just fine but is getting wet, but has not yet turned to mush or delaminated. Without a MM you'd never now there was a leak you needed to stop.

I once did an experiment with two surveyor friends. I sounded a boat and used the MM. I then asked them to only use only their hammers and tell me where the four areas of elevated moisture were. Both surveyors found one of the spots that had delaminated but the other three that had readings into the 20% range were undetectable to them via soundings alone. Often times when you find it with a brass or phenolic hammer the big damage has been done. The use of a MM can catch small changes before they get to bad.

As a person who has been on both sides of a MM, using it by mapping a deck, then digging up the deck, I can assure you they can be a very useful too when used to determine wet core, IF used correctly.

It's good to know we still have some honest surveyors out there! Kudos to your guy for being honest.

This is an example of what a saturated core looks like during the rotting process. If you look ahead of the chisel you can see how the balsa just turns to mush when you touch it with the chisel. This was a deck penetration under a teak hand rail.


Here's another view of a saturated balsa core. As you can see the balsa actually looks wet and you can physically see the moisture.

One should note that this balsa, even in the present condition, still adhered quite well to both the top and bottom skins and required a screw driver to pry this square from the rest of the deck. At some point this would have failed. Even this wet, the deck was still sounding out with minimal differences in tone even to a well trained ear. To the untrained ear, without a moisture meter and only a hammer, one might assume this deck was in good condition.

This is a good example of why spot soundings and moisture readings should accompany one another.



This is the adjoining deck section to the photo above with the chisel. As you can see the color of the balsa is telling you how wet it is. If you scrape out this core and compress it between your fingers it drips water like a sponge would. It should be noted that at this stage of rot (early) the core is still tightly bonded to the skins. If this moisture were allowed to continue the color of the balsa would continue to darken and literally rot away leaving no strength.

[bottomscraper]

"Moisture meters" are the divining rods, the tea leaves, the monkeys' entrails, the "eye of newt" of the fringe element of the Marine Surveyor business.

No not really. On cored areas like the decks of our CD's
they can be very useful in finding wet core. They come with
instructions that the user should read. What is more significant
than the actual meter reading is variations in readings. They are
very capable of detecting areas with higher moisture than
others. They are not some sort of magic trick, they are actually
based on real science but do require some understanding of
how they work and how they should be used. Much technology
was thought to be magic by the uninformed.

[Oswego John]

Hi Robert,

So far, you have been given lots of good info. I certainly can't improve on what has been said. I can add some generic comments on testing a hull, (mostly about cored decking).

I'm just assuming the following:

With no knowledge on the hull, since it might be located in New Jersey, at this time of the year the boat has a very good chance of still being on the hard. If this be so, I would think that the hull has had a long period to dry out.

From my limited experience, a hull in winter storage provides ample opportunity for anyone to inspect it any manner they may choose. Serious flaws can sometimes be easily spotted by observation. This is especially true when problems of delamination and such will, in most cases, be readily apparent.

Since (if) the boat is on the hard, there should be no hassles on who is paying for the haulout, for how long, and any other associated fees like yard storage. A person can thump away as long as they want, where they want, topsides or below the waterline. Chances are that fresh bottom paint (hopefully) hasn't been applied yet.

With the boat still on the hard, it shouldn't be a big deal for someone to inspect the masthead and associated fittings. The downside is that you won't get as complete an inspection of the engine, cooling system, tranny and drive to the prop.

I have included some info on moisture meters, different types i.e. bipin and non-intrusive electromagnetic (fancy name) technology.
This info will give you a better understanding and knowledge of some terminology and techniques when dealing with a surveyor.

http://www.electrophysics.on.ca/e_index.htm

Scroll to Marine Fiberglass/wood pinless meters

Click on blue icon on the left "FIBERGLASS BOATS"

Scroll down to New-DOLPHIN METER. Click Rayplex

Click on DOLPHIN MOISTURE METER, more information.

#1 MISTAKE in buying a Used Boat (Avoid Buyers Remorse)

Jump around different included articles to learn more.

Good luck,
O J

[Maine_Buzzard]

One caveat OJ-

I'll never thump a frozen boat...

[Sea Hunt]

Russell, Maine Sail, Rich, OJ and all:

Thanks very much for the information. I learned a lot

Maine Sail, as always, your photos are very educational. "A picture says a thousand words".

As dumb as I am it is certainly possible the surveyor who said he does not use a moisture meter was referring only to his inspection of the hull of a Cape Dory, not the deck and cockpit area, etc. He seemed very knowledgeable and polite and willing to spend time talking with me. Thus, his comment about moisture meters struck me as unusual. Based on your educational responses it now makes sense. Thanks

Maine_Buzzard I want to assure you I will NEVER inspect a frozen sailboat. It goes against every fiber in my being to go anywhere where the temperature goes below 50 degrees at night.