Boat Owners & Moisture Meters

[Maine Sail]

For a long time I have been a proponent of boat owners, especially those in the buying process, owning moisture meters. It's been a few years but I finally got around to doing an article on DIY use of a moisture meter.

Moisture meters can be had for well under $200.00 and will pay for themselves ten fold over your boating life. In fact they are free usually after the first use.

Please don't buy the hype and scare tactics used by "surveyors" about how "difficult" using a moisture meter is. It is fairly straight forward and easy for how and why you would want to use one. By owning a meter you are NOT circumventing the need for a real survey but you can use one to "rule out" certain boats or to create a map of the moisture in your current boat and monitor it's worsening or stability or to effect repairs in moist areas.


I know sailors are an overly "cheap" lot of folks but moisture meters, like almost any tool used by a DIY, are FREE! Think about this:

You bring your wife to look at a boat and she and you fall in love. The boat looks good and it has been cosmetically maintained and has new sails and low engine hours. You make an offer subject to survey. On the day of survey you find serious deck core rot and delamination in some critical areas and decide NOT to move forward with the deal.

At the end of the day you still cut a check to the surveyor for $500.00+ dollars and have nothing ot show for it but an empty wallet!!!!

If you owned your own meter you would have saved $300.00+ dollars, a day of your time, plus had a meeter to show for it that you can use on the next "specimen" in your search!

Feel free to read the article. The basic understanding needed to rule out "basket cases" or "money pits" is easy stuff!

P.S. I have zero affiliation to Electrophysics but do find the CT-33 to be the current best value in a DIY moisture meter. I used to own a J.R. Overseas GRP-33 but after I dropped it off a boat onto a tar parking lot I replaced it with the very similar CT-33. The GRP-33 had paid for it's self about 30-40 times over by the time I stupidly dropped it by not zipping my pocket!

Understanding The Moisture Meter / Electrophysics CT-33 (LINK)

[FarCry]

Great post and a well written article, thanks.

[dgr]

Halek... Maine Sail,
Thank you for the great article. I just ordered a moisture meter now that you've educated us.

[BarryL]

Hello,

Very nice post. And I think I will buy a meter for use on my own boat. I think it will be very handy to know when and where I need to take action.

Anyway, it's one thing to know (or think you know) there is some moisture in the deck (or hatch or ...), it's an entirely different thing to know if it's important, EXTREMELY important, or just something to be aware of. IMHO, that is what the surveyor is supposed to do.

As you wrote, using the meter is not just a simple matter of seeing 'Oh, the deck is wet in this sport, better pass on this boat.' because you may be passing up a perfectly good boat that just needs a simple repair. I know that I am not qualified to know what is simple and what is complicated. I want to pay a professional for that knowledge.

True, if you find a boat that looks good, and your meter shows wet everywhere, you will have saved the cost of the survey. BUT, in the hands of a novice, I think the meter is just as likely to cause someone to reject a boat that is probably pretty good.

I guess if you plan on buying a boat every 10 or so years, and don't want to learn a lot about boat buying, you are better off just hiring a surveyor. If you plan on buying lots of boats, or are interested in a make that is prone to core damage (certain C&C models) you might want to invest in a moisture meter, and to learn how to interpret the readings, and what to do with high reading values.

Thanks again,
Barry

[sander06]

We had our boat surveyed with a moisture meter and the guy found "significant" moisture in the rudder. Interestingly, the rudder was solid fiberglass and it was impossible for it to be saturated. He then noted that bottom paint can give a moisture meter a false positive for moisture. Of course, he also said that the 25-year old cutless bearing was in good shape, too!!

[Maine Sail]

Originally Posted by sander06

We had our boat surveyed with a moisture meter and the guy found "significant" moisture in the rudder. Interestingly, the rudder was solid fiberglass and it was impossible for it to be saturated. He then noted that bottom paint can give a moisture meter a false positive for moisture. Of course, he also said that the 25-year old cutless bearing was in good shape, too!!

How did you confirm the rudder was solid glass? If I'm not mistaken you sail a Westsail 28? I have seen the insides of a couple of Westsail rudders and they were both foam cored. Both had split from absorbing water and then freezing. The yard removed the skins and re-built these rudders.

[Joesaila]

Kidding on that. Great information. We bought a 77 Morgan a year ago and did so w/o a moisture meter. Now that I've read this I can't believe the surveyor didn't use one. I think he was good and used a mallet for sounding but the meter is obviously superior. I am curious about the picture that showed a high reading near a waste water cover. Would the closenes affect the reading? Thanks again though!

[sailingdog]

That probably means the deck fill was installed without removing the core or potting the fastener holes properly...so that water is entering the deck at that location.

Originally Posted by Joesaila

Kidding on that. Great information. We bought a 77 Morgan a year ago and did so w/o a moisture meter. Now that I've read this I can't believe the surveyor didn't use one. I think he was good and used a mallet for sounding but the meter is obviously superior. I am curious about the picture that showed a high reading near a waste water cover. Would the closenes affect the reading? Thanks again though!

[boatpoker]

Any surveyor that needs a moisture metter to find "wet, rotten" core is not worth his salt whether it be in the hull or deck Percussive soundings of a couple of thousand boats has proven more accurate for me.

The comment about certain bottom paints affecting the meter readings is correct. Moisture meters do not measure moisture !
The GRP33 is a capacitance meter that measures the capacitance (measured in farads) of the substrate with the theory being that a higher moisture content will have higher capacitance. As they measure capacitance rather than moisture many things will affect their readings such as conuctors or metal tanks in contact with the area being measured, certain gelcoats containing titanium dioxide, copper oxide, carbon and several other compounds with high capacitance (the same reason some bottom paints cause high readings.

These meters are a guide only ,they will show the casual user that some areas have higher capacitance than others..... but what does that mean and is it worth the $200.00 for the meter.
These meters can be of some use to the casual user but to stick one on a surface and say "thats wet" is only about ten percent of what you need to know.

I keep an eye on this forum but rarely post so I don't think I can show a link but I do have an article on my website entitled "Moisture Meter Myths" that goes into some detail on the strengths and weakness's of these meters.
If you put "Port Credit Marine Surveys" into one word and then add dot com that should get you there.

"Dirt People Scare Me"

[sander06]

Originally Posted by Maine Sail

How did you confirm the rudder was solid glass? If I'm not mistaken you sail a Westsail 28? I have seen the insides of a couple of Westsail rudders and they were both foam cored. Both had split from absorbing water and then freezing. The yard removed the skins and re-built these rudders.

Actually we have a Liberty 28 Cutter that is very similar shape-wise to a Westsail 28 but without all of the associated problems. The Liberty boys figured out the problems Westsail had with soggy rudders, wet decks, etc. and fixed the issues (I think that's called "back-engineering"), anyways the boat specs say that the rudder is solid. My main comment is concerning surveyors who, rightly or wrongly, I have near universal disdain. Just my opinion and I could be wrong.