Osmosis: Don't Worry, Be Happy !

[Geminidawn]

Curing osmosis is not rocket science but it is labour intensive. You start with removing the affected gel-coat and the unsound laminate you can do this yourself with a steady hand a flapdisk and an angle grinder or hire a peeler to do it for you. The hired hand usually dose it with a shot blaster or a gel-plane.
Once that is finished you do your first litmus and moisture reading tests the acidity and moisture levels initally will be quiet high but you have to record them anyway as a starting point. That done you power wash the stripped hull sometimes twice daily with fresh clean water to neutralize the acid and draw out the contaminants. Take both moisture readings and ph levels on a weekly basis.
Once the moisture levels fall into the green (approx 13% or less) and the hull reads close to a ph neutral it's time to seal her up again.
The process dose take time if you want a quick fix you are looking at a Hot-Vac system which is costly and uses specialized equiptment.

[bludden]

Originally Posted by miami privilege

Hey its just the way it is when it comes to Resin. A few of the posts were accurate in stating the glycol, a hydrophobic action creates blisters. This is true on all fiberglass hulls. Its the extent that this happens and how noticeable it becomes. I wouldnt get overly anxious about this matter. Water inside the hull and outside will create this affect. My older boat sat in water for 20 years before it needed to be repaired. Fiberglass technology has been around for quite some time. If your around boat yards enough you see it every where on older boats. It a little like rust on metal the older it is the more you find
In my case I needed the antifouling done so I bit the bullet and stripped the gel coat and replaced it with 15 gals of epoxy. I didnt have it peeled but in retrospect would have gladly paid the 2500 in the states to have this done. Truely its not as big of a deal as many make it out to be. After 10 years of having fun on your new cat, have it hauled peeled and be happy. My waterline jumped up 4 inches after I finished mine. Its about 2-3 days for peel then roll on epoxy, hot coat is the best. If you want more details private message me.

Thanks Miami, but as my original post says, why are we faced with this problem? The fundamentals of osmosis have been understood for 30 years or more; indeed as soon as epoxy became commonplace in boat building it's been touted as a cure. Your Privilege would have cost (and I'm guessing) perhaps $500,000 Aus. or more in today's dollars. Instead of gel coat, if they'd sprayed or rolled epoxy below the boot top you probabaly wouldn't have needed a peel. The incremental cost to the production cost would have been miniscule !!

I assume you painted your waterline higher and you don't mean your boat floats 4" higher after your barrier coating?...Cheers

[sabray]

Heres how I see it. Polyester resin dissolves in water. warm water and low salinity dissolve resin faster. Bad resin mixes are bad and dissolve even faster. resin can dissolve without making a blister. Epoxy and vinylester don't dissolve or do it much much slower. Old boats had osmosis but they had way lots of lay up and glass. Newer boats have designed ratios of resin and cloth and were engineered to tighter standards. You need to get the wet stufff dry or remove it for a repair. Sometimes its just peel the gel or gel and finishing layer let it dry and coat with vinylester etc...
Sometimes its a big deal depending on the boat and sometimes there is so much glass it doesn't matter and never will. I did this for a living years ago. Some boats really had problems and sometimes we were fixing them before it became an issue.

[Geminidawn]

Originally Posted by bludden

why are we faced with this problem? The fundamentals of osmosis have been understood for 30 years or more

The short of it is the sea dissolves everything in time, where you have steel, you have rust, where you have wood you have rot, aluminium, you have oxidation and fibreglass, osmosis.
Every man made thing on earth will eventually find its way back to the elements from which it was formed and nothing amplifies that more than the marine environment and if the water dosen't get it the Sun will, even epoxy will loose all it's structural strenght and break down fairly rapidly under UV if it's not well protected.

[CharlieCobra]

We have this boat in for pox repair. It was built in the 80's and as you can see, it's extensive.



and

[bludden]

Originally Posted by CharlieCobra

We have this boat in for pox repair. It was built in the 80's and as you can see, it's extensive.



and

How deep have you had to grind to remove the bubbles and what layers of the layup were affected?...Could you describe your method of repair?...Cheers

[Geminidawn]

I am interested myself, rather than target blisters, I use the method of stripping back everything layer by layer until I reach a sound surface as blisters or pox can be conjoined via wicking action.

[perchance]

I am looking at the keel and can't tell if it's encapsulated or external. If it's external why the pox?

[perchance]

Originally Posted by bludden

Thanks Miami, but as my original post says, why are we faced with this problem? The fundamentals of osmosis have been understood for 30 years or more; indeed as soon as epoxy became commonplace in boat building it's been touted as a cure. Your Privilege would have cost (and I'm guessing) perhaps $500,000 Aus. or more in today's dollars. Instead of gel coat, if they'd sprayed or rolled epoxy below the boot top you probabaly wouldn't have needed a peel. The incremental cost to the production cost would have been miniscule !!

I assume you painted your waterline higher and you don't mean your boat floats 4" higher after your barrier coating?...Cheers

Must have been a lot of water in the glass for it to jump 4 inches.

[ozskipper]

Originally Posted by CharlieCobra

We have this boat in for pox repair. It was built in the 80's and as you can see, it's extensive.

What make model is the boat?

Cheers
Oz

[CharlieCobra]

I don't know what she is, just that it's an 80's boat and 28', center cockpit, aft cabin. The deepest we went was 1/2". The deeper ones were laid in with fabric and epoxy. The rest were all hit with epoxy with fiberfill over that. We're currently waiting for this cold snap to end to finish. Not fun working outside in 16F and 50 knots of breeze...

[bazzer]

Originally Posted by CharlieCobra

I don't know what she is, just that it's an 80's boat and 28', center cockpit, aft cabin. The deepest we went was 1/2". The deeper ones were laid in with fabric and epoxy. The rest were all hit with epoxy with fiberfill over that. We're currently waiting for this cold snap to end to finish. Not fun working outside in 16F and 50 knots of breeze...

As a matter of interest why did you not just plan the entire gel coat off and replace it with a epoxy barrier coat?

Baz

[CharlieCobra]

I wanted to, the owner didn't wanna spend the money. He flips boats................. (imagine me hitting that period one at a time slowly).........

[arco]

If I had a boat with a hull which was a one piece vacuum mould and was about 5 years old, and I was to guess the resin is seriously suspect because the hulls are almost as wet above the waterline and across the bridgedeck as under the water, and that the bridgedeck was currently showing a small area of delamination, would I be right to think that my asset would be seriously devalued, and that the longterm structural integrity would be severely compromised?

[Geminidawn]

Originally Posted by arco

If I had a boat with a hull which was a one piece vacuum mould and was about 5 years old, and I was to guess the resin is seriously suspect because the hulls are almost as wet above the waterline and across the bridgedeck as under the water, and that the bridgedeck was currently showing a small area of delamination, would I be right to think that my asset would be seriously devalued, and that the longterm structural integrity would be severely compromised?

On just what you've written YES! and if it is as bad as you say I think it is time you got a survey report.