Moisture meter?

[windblown]

I’m considering picking up an inexpensive pinless moisture meter to check some deck areas (around the dorade, around a couple of stanchions, etc), but I understand they can be tricky to use, and it looks like lower-end models are mostly for drywall or exposed wood. Any words of wisdom?

 

[Frank Langer]

I have used one, and agree that they are inexact. You need to take into account where there is simply balsa core vs. plywood or epoxy, as they will read differently.
Where it can be helpful is when you check two similar areas, and one shows a much higher reading, like checking both chain plates, they should be similar if one hasn't been epoxied by a previous owner.
Let us know what you find if you decide to try it.
Frank

 

[Kenneth K]

I've done (and am still doing) many small deck core repairs. Never used a moisture meter. If you are thinking of using one, you likely have already encountered signs of moisture: drips, leaks, discoloration, rusted fasteners, soft spots, bulged spots (after freezes), mold. Only surefire way to determine that I've found is to start drilling 1/4" to 3/8" holes in the core from below. You'll know right away if the drilled wood chips are dry, damp, or soaked. Drill in a grid pattern with holes spaced 4-6" until you know you've found dry wood.

Dry: (under center dorade vent railing)

Wet:
(stanchion base above V-berth)

If you mistakenly drill holes into dry core, just re-fill with thickened epoxy using a syringe. At least you'll know for sure.

 

[jtsai]

I have a moisture meter manufactured by electrophysics in Canada after read R.C's article. I bought it 10 years ago to assess extent of moisture ingress on a Sabre 28's cabin top from poorly installed teak handrails. It has been a valuable tool for boat shopping. When used properly, it reveals areas with excessive moisture before spending time or money for further considerations.

As others have already pointed out, the moisture meters are best used to compare one known dry area to a questionable area with identical substrate. It is not a voltage meter that gives your exact number, it estimates electrical conductivity across the probe or plate.

It is the most borrowed tool among my boating friends.

Temporarily Disabled

 

[windblown]

Inexpensive pinless moisture reader arrived today. I haven't had a chance to try it out at the boat yet, but I couldn't wait to try it, so I started taking readings around the house. We've seen some evidence of moisture in a small area on one wall in the family room--not enough moisture to cause a bubble or run in the surface, and not enough to feel a difference in the temperature or any dampness through the paint-- but just enough to cause a slight distortion in the surface if you look at it from just the right angle. Well, the meter on the drywall setting didn't pick up much moisture where we thought it would, but several inches to the right, it set off the alarm! I'm pretty I was right over the stud, which seems to be holding some water. The reading was from a few inches above the baseboard to about 3 feet straight up. As it happens, we have some plaster and dry wall repair scheduled for tomorrow.

I've done (and am still doing) many small deck core repairs. Never used a moisture meter. If you are thinking of using one, you likely have already encountered signs of moisture: drips, leaks, discoloration, rusted fasteners, soft spots, bulged spots (after freezes), mold. Only surefire way to determine that I've found is to start drilling 1/4" to 3/8" holes in the core from below. You'll know right away if the drilled wood chips are dry, damp, or soaked. Drill in a grid pattern with holes spaced 4-6" until you know you've found dry wood.

Dry: View attachment 45560View attachment 45555 (under center dorade vent railing)

Wet: View attachment 45559 View attachment 45557 View attachment 45558
(stanchion base above V-berth)

If you mistakenly drill holes into dry core, just re-fill with thickened epoxy using a syringe. At least you'll know for sure.

Kenneth, your photos and technique are very helpful. I see some poking and prodding in my future.

 

[Frank Langer]

Many years ago I drilled small 1/8" holes into the underside fibreglass of the deck (ie. from inside the boat) about every 18 inches, and the small amount of material in the drill bit showed the core to be dry. I left the holes open so I'd get early warning if there was water entering the core, for example near chainplates. It's easy to check those holes and the headliner under the holes for moisture by opening the headliner zippers periodically. That also keeps the zippers functional.
Frank

 

[JPWhite]

I have a Klein ET1140 Pinless moisture meter that I have used for when looking at boats (I use it to check the RV roof for potential leaks as well). As noted above, it works well to get relative readings.

I've looked at a couple of boats where it has come in handy. I run it across the hull and the decks watching the readout. I pay closer attention to areas where it spikes. There are multiple settings for drywall, softwood, hardwood, etc. I switch settings in those areas, and move it around again to see if I get consistent results. The percent moisture reading may not mean a lot, but areas where it is off the scale wet with all settings does indicate a problem. I use a small sounding hammer as well. Areas showing wet with a dull sound indicate potential problems I do not want to inherit. For me, it is a useful tool. My goal is not to figure out where to affect repairs, but rather or not to proceed to a survey.