Hull Osmosis

[Sailmonkey]

I was wondering the same thing........I thought sanding almost to the gelcoat was what one did when re-painting the bottom?!?

[swagman]

Hi Solosailor,

I'm sure when the hull is checked with a moisture meter you'll find out if it is 'a little osmosis' or a bigger issue. As most Contessas were well built I hope its the first, but if not then put it aside and look at other boats.

Good luck
JOHN

[WGDM]

Well,the reason that the sanding was done was to take all of the old antifouling off of the hull and start afresh as layers had built up over the years and it was so thick that it "moved" when lift straps were used to haul her.....They did exactly that,although there were some places that were not sanded right down to gelcoat,but very close.....ie as she came out of the mold.
They then applied a base grey sealer and then the new antifouling paint.
I am not completely happy that the sealing was properly done but there is no redress at this late stage;There was already Osmosis there,anyway.
So,I was really just looking for some preferable places to have her hauled and peeled and re-glassed etc,in the West Indies or the South American Mainland by folks who know what they are doing and in a specific timeframe,agreed beforehand.
Thanks,WGDM

[Nauticatarcher]

IMHO the best way to fix a few non structural blisters is to just put your boat back in the water, out of sight out of mind, if a 20yr old boat hasnt sunk from them yet its highly unlikely its going too

[WGDM]

The state of the hull seriously affects the value of the asset and a boat,of any type,with a rotten core,is worth only the sum of its parts.Osmosis can also weaken the hull if allowed to leach.
Constructive posts are much better,but thanks anyhow.And,of course,she has not had blisters for 20 years!
Regards,
WGDM

[SaucySailoress]

Originally Posted by WGDM

And,of course,she has not had blisters for 20 years!
Regards,
WGDM

This sounds more recent than twenty years ago...

Originally Posted by WGDM

When we hauled 6 months ago we found that the problem was now much,much worse with not only new blisters,but much bigger ones,and more liquid

Maybe I'm misunderstanding something...

[WGDM]

Possibly you are----the previous post said that if she had not sunk after 20 years (of blisters) she was unlikely to do so now.........I have never said that the boat has had blisters for 20 years (!)-----I said they had been visible for 12 months.......would be useful if everyone read the posts more carefully.
Anyhow,thanks for yours and I have my answer so far.Peel and fix in the dry and dry for about 3 months.
Best wishes,
WGDM

[zeehag]

Originally Posted by WGDM

Possibly you are----the previous post said that if she had not sunk after 20 years (of blisters) she was unlikely to do so now.........I have never said that the boat has had blisters for 20 years (!)-----I said they had been visible for 12 months.......would be useful if everyone read the posts more carefully.
Anyhow,thanks for yours and I have my answer so far.Peel and fix in the dry and dry for about 3 months.
Best wishes,
WGDM

wgdm..as you have a cored hull, i do recommend your course of treatment--as i had solid hulls i was advised that normally, small blisters are no big deal if they donot tunnel or grow or pop. as you have a cored hull. and your boat is growing heavier, i would definitely go for the good fix. make hr solid again.
she is a worthy boat--make sure she is goood and dry..and barrier coat, after the fix to over the level of the boot stripe at its highest point--and reboot her. then no water can get into the underwater part as easily--it will have to work.

[Pete7]

If the hull is cored below the water line, how is he going to dry it out?

Shaving off the gelcoat, although if it was done 12 years ago its going to be epoxy surely, is one thing but then what. He is left with a layer of GRP, inside that is the core and an further inner layer of GRP inside the boat. How does the core dry out?

Pete

[WGDM]

Thanks my friend,
Well said.She is a good old girl and has a couple or three hundred thousand under her keel and was built really strong by Formosa in the days when they had no idea just how strong `glass was/is!
We want to fix her properly and as she has a core,its a peel,I am afraid.
Bite the bullet I guess and take it to just about the bootstripe (she lies loaded with the antifouling just visible) and all will be well.
Thanks so much for your input.
Sincerely,
WGDM

[WGDM]

I guess they weep back out the same way the water went in----through the glass lay-up.
I would also suspect that these early boats have open-cell foam?
As I see it the gelcoat is the supposedly impermiable layer;The water has wicked through that into the mat/resin and then across into the core (in places).This has to stand and dry out but be washed every morning with fresh water to wash away the residue.......anyone have any other ideas here?
WGDM

[CharlieCobra]

Nope, peel to mat and let her dry with daily FW rinses to wash away the acid that will be leaching out. It's gonna take at LEAST three months, maybe a bit longer. Zee has the right idea of going to the top of the boot with both the peel (what's another foot gonna cost?) and the barrier coat. Be sure that when you apply the BC that it's at least 10 mils thick DRY or you'll be wasting your time.

[WGDM]

Continuing this thread----has anyone had any experience of having work done in Venezuela?I was thinking of getting down there (where?) and having the Osmosis looked at."Expert opinion now indicates that it will be possible to do a repair by attending to individual bubbles which are in specific places,not all over the underwater areas.I understand that the climate is very dry and may be good for this kind of work----but where?Any advice,guys and girls?
Thanks very much.

[cburger]

I do not have any insights regarding getting work done in South America however a couple of thoughts on the worsening blister problem with your hull.

My instincts are telling me that you are experiencing issues with wet core.
I am sure you know that all that is required is a compromise anywhere underwater and open celled foam acts like a sponge. I do not know the construction methodology of your particular boat but through hulls are a typical source of water ingress into the core and depending on any additional underwater openings into the boat since she left the factory they may be causing issues if they were not sealed properly. There is a strong school of thought that water inside of boats in unprotected bilges are a cause of osmosis, and the list of possible water source points go on and on.

In your particular case the fact that the hull was peeled and epoxied? 12 years ago and you are still have problems that are getting worse I am thinking that the issue is from the inside out.
Once the core is wet areas of resin starved fiberglass strands that lay against the core soak up the water and form blisters regardless of what was done to the hull on the outside. Tropical climates heighten this problem.

If this was my boat I would have it bead blasted down to its bare bottom in order to do a real good visual inspection of everything below the water line. I would then hire an expert surveyor to go over the hull with a moisture meter as well as sound the hull with a hammer, the idea is to try and isolate the really wet areas to help determine the next cause of action. Finally I would take a 2" hole saw and take a test plug right out of the middle of the wettest area being careful just to remove the outer glass and inner core, not the inner glass.

The last wet cored boat I saw this done on the water came out of the test hole like it was under pressure for several days, the owner spent several more days with a good shop vac sucking out all the water he could from the core. If this turns out to be the case with your hull it is also important to determine and repair the source of water into the hull or you will be going through all this nonsense again.

Additionally the assumption that a hulls gelcoat is there as a waterproof coating is a misconception. while the gel does initially offer some barrier to the water, it is in fact a pourous material and its main purpose is cosmetic. This is while you will often see knowledgeable owners epoxy barrier coating brand new hulls before they are ever floated.

Good Luck

[osirissail]

In Venezuela one of the best places to do work on your boat - if you survive getting there - is Medregal Village Marina in the Golfo de Cariaco. It is in a "desert" area and very dry. However, you would need to bring all your needed supplies/equipment with you along with the knowledge of how to accomplish the job. Then you can hire very reasonable workers and train them to do the job. The heat down there can be oppressive so having locals do the 'grunt' work is a good idea. But you need to supervise and train them.