Osmosis survey question

[jon and michie]

So here is just a question - How would a Surveyor check for osmosis on a copper coated Hull without causing damage ?
my last boat had antifoul which the surveyor scraped back and all what was required was to re antifoul the scraped areas
So would it be the same procedure and just copper coat the affected areas?

Jon

 

[markc]

I always assumed that because Coppercoat is an epoxy, it's a barrier to osmosis, so the hull should be pretty dry. Also, unlike regular eroding antifoul that takes a while to dry, I don't see that Coppercoat needs to be scraped off for the moisture meter to work.

 

[jon and michie]

I always assumed that because Coppercoat is an epoxy, it's a barrier to osmosis, so the hull should be pretty dry. Also, unlike regular eroding antifoul that takes a while to dry, I don't see that Coppercoat needs to be scraped off for the moisture meter to work.

good point - so a moisture check could be carried out without the need to be scraped back - say if an oldish boat had coppercoat applied and the hull had already dampness already this should show up

 

[Refueler]

1, Depends on the meter used
2. Depends on how dry the hull was when Coppercoated
3. Depends on how many coats / layers of Coppercoat and any primers used

In theory you should be able to determine whether hull is dry or wet... if you want greater accuracy - the above 3 come into play and no-one can be sure.

 

[stelican]

Doesn't a moisture meter work on continuity? Copper is probably the best conductor available. Seems like the professionals use a Soveriegn meter which works on radio frequencies.
info from past threads.

 

[volvopaul]

So here is just a question - How would a Surveyor check for osmosis on a copper coated Hull without causing damage ?
my last boat had antifoul which the surveyor scraped back and all what was required was to re antifoul the scraped areas
So would it be the same procedure and just copper coat the affected areas?

Jon

The blisters expand so you can see the protrusion

 

[ChromeDome]

Osmosis is discussed a lot.
Have anybody ever heard about an accident or even sinking resulting from it?

 

[RunAgroundHard]

Osmosis is discussed a lot.
Have anybody ever heard about an accident or even sinking resulting from it?

yet when it is found the buyer wants a discount to rectify. What is that all about if there is no risk?

 

[Neil1300r]

Yes, according to this article
Osmosis on a boat: will it cause my vessel to sink? - Practical Boat Owner.

Even if it doesn't cause them to sink if you have 2 boats to choose from, one with osmosis and one without then like me you'll buy the one without it. So, it can make a boat more difficult to sell

 

[Refueler]

Doesn't a moisture meter work on continuity? Copper is probably the best conductor available. Seems like the professionals use a Soveriegn meter which works on radio frequencies.
info from past threads.

Soveriegn Meters are old hat and of limited penetration depth. They have been surpassed many moons ago by the likes of the various versions of Skipper Meters.
I was one of the first on South Coast UK to use the first edition Skipper many years ago ... and often compared to Soveriegn ... I also carried a Protimeter for other construction materials (wood etc).

 

[Hacker]

I guess you could use the meter on the hull in the bilges?

 

[Refueler]

I guess you could use the meter on the hull in the bilges?

Not really ...

The usual is that moisture is between the outer Gelcoat and first layer or so of the laminate ....

If its wicking (where a 'dry strand' allows moisture to follow it into the laminate) then it can be deeper.

 

[stelican]

Soveriegn Meters are old hat and of limited penetration depth. They have been surpassed many moons ago by the likes of the various versions of Skipper Meters.
I was one of the first on South Coast UK to use the first edition Skipper many years ago ... and often compared to Soveriegn ... I also carried a Protimeter for other construction materials (wood etc).

It was a very old thread
Thanks for update.

 

[Refueler]

It was a very old thread
Thanks for update.

I can believe that !!

In those days - the Soveriegn was promoted by a certain group and became a standard item. But it was actually very poor as it was never intended for this work. Despite the blurb given out those days !!
Meters were initially based on Builders gear used for Stud / Water detection in walls etc. few tweeks here and there and you had a Moisture Meter for boats.
Tramex along with others - spent time and effort to move away from that and derive a better - more penetrative solution.

Example ... Not an isolated single observation but noted more than a few times : Soveriegn showed hull as basically dry and ready to Gelshield. My Skipper showed that laminate still was not dry

That in itself should tell you something about the metering of hulls ... its not cut and dried as people think and goes back to my points earlier.

In the past - many have had Osmosis treatment and only a few years later observed signs of it again .. who is to say it may be down to the meter used and saying hull was dry when maybe it wasn't ?? Who knows ??

 

[Sticky Fingers]

Just had a boat surveyed, the surveyor used the Tramex Skipper Plus for this task, albeit 'twas standard Antifoul not CC.

 

[Refueler]

I checked out my own boats and a few others in the yard here with my Tramex .... no charge - friend to friend.

 

[ChromeDome]

Yes, according to this article
Osmosis on a boat: will it cause my vessel to sink? - Practical Boat Owner.

Even if it doesn't cause them to sink if you have 2 boats to choose from, one with osmosis and one without then like me you'll buy the one without it. So, it can make a boat more difficult to sell

I know and appreciate that. Like when looking at cars - one has a dent the other doesn't.

So if the boat that has or is suspected of having osmosis (or just delamination) is significantly cheaper, it could be a financial argument

 

[Plum]

Not really ...

The usual is that moisture is between the outer Gelcoat and first layer or so of the laminate ....

If its wicking (where a 'dry strand' allows moisture to follow it into the laminate) then it can be deeper.

Actually, that is only one mechanism by which water will get in. Water vapour will pass through polyester resin (unlike epoxy resin) and that vapour will condense into liquid if it reaches any voids.

 

[Refueler]

Actually, that is only one mechanism by which water will get in. Water vapour will pass through polyester resin (unlike epoxy resin) and that vapour will condense into liquid if it reaches any voids.

Please re-read ... I said IF ITS wicking .. which in fact is not Osmosis ...

It was in answer to depth of testing by metering in bilge.

Moisture CAN pass through Epoxy - but at a vastly reduced rate ... literally to a near zero rate.