osmosis

[newf]

anyone heard of osmosis in a cabin roof ?

[petersjoy]

Guess you are talking about Brian's recent survey?

[Guest]

If by that you mean blistering in the gel coat II have heard of it on cabin sides Colin so I guess it's perfectly possible in a roof. Apart from being a bit unsightly I would not have thought it was a serious issue, certainly not from a structural point of view - unless the blisters are huge anyway.

[Antares_9]

You really need immersion in a solution for an osmotic effect to take place so it’s unlikely, if there are blisters in the gel coat try bursting one and see is it smells like vinegar then it could be otherwise there is probably some other reasons for the blisters. I’ve certainly never heard of it happening above the waterline. There may have even been some fault, either voids or trapped moisture at the lay up process, again most unlikely. Maybe a description of what's happening?

[newf]

Apparently this was not visible but detected (?) by tapping and finding a hollow sound, this was by a surveyer and the suggestion was 2K to put it right and consequence loss of sale

[Antares_9]

Well I would have thought any surveyer would be using a mosture meter to detect the effects of osmosis unless there is very obvious blistering, what you describe sounds more like delamination or void detection (the tapping), most odd indeed.

[Guest]

Hi Colin

I knew the guy was taking the water

I told Brian to get a second oppion

Jonny

[petersjoy]

This is short version i got,

The short version:

> Hull, all good, no osmosis, engine good and so on, "BUT" osmosis

> was found on both of the two roof corners (they tap around for

> hollow sounds).

> All the paintwork looked perfectly ok, but apparently would cost

> around 2K to cut out and do the repairs...... The prospected buyers

> pulled out. (no barter... nothing)

[Antares_9]

That's very telling Paul, corners, particularly tight compound curves are an area where voids can easily occur with hand layup if the laminator is having a bad day or not paying attention. But osmosis??? It would be foolish in the extreme to say that it's categorically not but it seems less likely the more I hear, if the guy suspected a high water content in the laminate why not confirm with a calibrated instrument to prove it to both buyer and seller. Then we must remember that the efects of osmosis can leave voids.

[Guest chriscraft]

it,s probably the re enforcing that sounds, hollow,they use ply to re enforce roofs and corners where heavy loads are anticipated,sounds a bit dodgy to me!!,would almost say certainly not osmosis,rotton wood maybe

regards trev

[newf]

Paul, exactly what I got from Brian and I know he was disappointed to say the least.

Jonny, I agree but second opinion is too late now , the damage has been done .

Thanks for your input again guys I was wondering if I had gone a bit dulally but not being an expert I did wonder.

[C.Ricko]

where foam was used in the sandwich layer in the past instead of balsa wood, the vibration of the engine over the years has been known to turn this into dust, perhaps this was the void?

normally a surveyors report is used to barter a bit, some times people 'add' bits verbally to what the surveyor says, so it is worth asking to see the report.

also remember that (not neccessarily in this case) 'whoever pays the piper calls the tune '

[Mowjo]

Clive is right it could be that if yours is the foam sandwich type construction, I had several spots like that on my Freeman 23, including loads on the deck and deck sides, the decks were quite springy, and there were several hollow spots on the roof, solution was simple, drilled a few holes and filled the voids with expanding foam, just do it carefully or the two skins expand too much and leave you with a big bump,, if it's wood inside the corners and it's just delaminated drill a few small holes in each corner and inject some epoxy resin into them once it's dry just fill the holes with Gel coat then wet and dry sand using finer and finer grits, use a bit of compound to flat it then polish,,, for 2k I'd want a whole new roof

Regards Frank,,

[Antares_9]

where foam was used in the sandwich layer in the past instead of balsa wood, the vibration of the engine over the years has been known to turn this into dust, perhaps this was the void? '

Bloody hell that’s scary Clive, think of all those Bayliners, Sea Rays et. al. built since the early ‘90s with foam core hulls, and not just the smaller ones. I guess you can only trust they use a different process or closed cell foam, I hope they do something differently.

[C.Ricko]

Bloody hell that’s scary Clive, think of all those Bayliners, Sea Rays et. al. built since the early ‘90s with foam core hulls, and not just the smaller ones. I guess you can only trust they use a different process or closed cell foam, I hope they do something differently.

Well, there are lots of different types of foam, you would have thought that by the 90s they would have worked out which ones were the problem. (I dont know )

anyway it should not affect the bigger boats as their owners are either too scared to leave the marina or too worried about putting hours on the engines

[Antares_9]

anyway it should not affect the bigger boats as their owners are either too scared to leave the marina or too worried about putting hours on the engines

I did wonder why some of the larger ones had letterboxes and roses growing around the porch.

[Guest]

It all sounds very strange Colin. Osmosis detected by a hammer?

As David said, by definition osmosis requires immersion in a solution so it cannot actually be osmosis, per se, on a gel coat not immersed. But that doesn't mean you can't get blistering in the gel coat and I have heard of that being diagnosed on another boat - in that instance on the sides of the cockpit. But here you're saying it's not immersed AND there are no blisters - but it's being called osmosis? Doesn't sound terribly scientific, unless there's a bit of Chinese whispers going on of course with the information being passed from person to person and "interpreted" at each stage.

[petersjoy]

Simon, the short version i posted is direct from the boat owner,

He must have got it from the surveyor,

as yet he hasn't replied to my email to let me know who the surveyor was.

So we cant him yet.

Paul.

[Guest me lady]

Re Osmosis

Thank you All for your comments re my survey, it was very unfortunate that I lost the sale.

It was Friday the 13th !

[pks1702]

Oh dear what bad news.

You seem avatarless - have this one on me