Moisture meter readings

[DavidGrieves]

Hi All

Need some advice about a Sovereign Moisture Master

My boat is a Colvic Sailor 29.5 1981 bought it last year, had the gell coat peeled, shot blasted and now hot water pressure washing every couple of weeks.

I have just got loan of the Sovereign moisture meter. I am using it on scale 'A' setting the redline and zeroing the needle.

My readings below the water line are between 5% and 15%

Above waterline well up the topsides they are between 5% & 10%


1. What readings are acceptable before re-coating?
2. Am I using the meter correctly?
3. Am I going to miss another season???


All advice welcome


Thanks

David

 

[Avocet]

Avocet was checked last year before I put a few more coats of epoxy on and apparently the average reading was about "12" but I don't know what meter was used. In any case, I was told this was fine for what I wanted to do so I slapped on a few more coats! PM me if you want to discuss further!

 

[TigaWave]

Have a search for old threads on this subject there were some comments in the past on moisture readings/meters. This also might be useful.
http://www.yachtsurvey.com/BuyingBlisterBoat.htm

 

[Birdseye]

The figure that the Blakes tech helpline gave me was 5. In most areas my own boat was down to 3.

Have you checked the zeroing of the meter? Then are you carefully prepping the surface where you are measuring - and dont neglect the effect of unseen condensation for example? And dont forget that the meter will also detect (depending on hull thickness) timber bonded in on the inside, and which will always give a way higher reading than GRP. And lastly, beware of curved surfaces - they tend to give false low readings unless you press on the sensor in which case they give false highs!

Your topsides in an area where there is no timber or metal should give you a "base" figure. Your bottom sides after treatment should ideally give the same result.

Apologies if the above is "teaching granny to suck eggs"

 

[boatmike]

You seem to be getting good comparitive readings thats the important thing. The scales don't really mean a lot in themselves but you should really try not to re-coat until your bottom is the same as topsides. I don't trust these bloody meters but can't think of a better way so have used them with caution myself. If in doubt there is no harm in you checking other boats in the yard to get a comparitive reading either.... would not be scientific but would give you a benchmark for your readings..... Must confess I do it myself to ensure that I am not getting daft results! Beware of wax polish though. Often screws up the readings. Most reliable readings usually come from dirty boats!

 

[andyroo]

I am not sure what the purpose is for taking moisture readings, but generally between 5% and 15% is acceptable. If you are intending to re-epoxy the hull the reading below the water line should be 5% or less.

I would start worrying if the rating was higher than 20% but the readings you are getting seem fine and would say another season is fine.

Word of advice: Make sure you take the moisture reading in the same place on several occassions, this will give you some indications of how well the boat is drying out.

Cheers.

Andrew

 

[andyroo]

Next time I should read your post!! Would wait for the reading to drop to less than 5%. I know some yards use a heat vac, which reduces the the moisture content really quickly. Otherwise, you might need to leave it for a month or so, with a dehumidifier on inside to dry it out a bit more.

Cheers

Andrew

 

[Stemar]

If you had any blisters, there's a fair chance that styrene left on the surface as water evaporates is slowing down the drying process, especially if it seems to have stopped drying. Strange as it may seem, a regular hose down with fresh water can work wonders.

Give it a day or 2 to dry before measuring!