Blister Treatment After 2 Years Ashore?

[Heathenly Twins]

I'm going to quit my job soonish and head back to the boat, it will have been ashore 2 years by the time I return. There were hundreds of little quarter sized blisters on the hull when I left it and I'm not sure if they are from osmosis or just a bad antifoul job. Will the blisters have retained their fluid after so long ashore or will I have to splash the boat and sail it a while to get them back to their largest before treating?

[Westcliffe01]

If they are osmosis blisters, they will still be there. The chap restoring Athena on Youtube (Saillife ?) took a considerable amount of time trying to dry out his laminate using silicone heating pads after it failing to dry out based on atmospheric humidity.



Use a small object to tap the surface, the blister areas will be delaminated and all of the delamination will need to be ground out, chemically neutralized and then built back up using epoxy and cloth. Removing the old anti foul may help before you start or else you will need to remove it anyway around each blister so that you have a clean feathered edge to laminate to, sounds like a pain if there are many blisters to remove.



That would allow you to address all of the blisters and then apply a proper barrier coat to keep the water out of contact with the polyester resin laminate that remains, else you will have more blisters to deal with as time goes on.

[Pandor]

I know this doesn’t help, but the ideal situation would have been to grind out the blisters 2 years ago. After grinding out, you need to let the hull dry out prior to repairing. Two years on the hard would have done wonders.

[Orion Jim]

Originally Posted by Pandor

I know this doesn’t help, but the ideal situation would have been to grind out the blisters 2 years ago. After grinding out, you need to let the hull dry out prior to repairing. Two years on the hard would have done wonders.

I agree. You are now going to start at step one.....

[Heathenly Twins]

Originally Posted by Westcliffe01

If they are osmosis blisters, they will still be there. The chap restoring Athena on Youtube (Saillife ?) took a considerable amount of time trying to dry out his laminate using silicone heating pads after it failing to dry out based on atmospheric humidity.



Use a small object to tap the surface, the blister areas will be delaminated and all of the delamination will need to be ground out, chemically neutralized and then built back up using epoxy and cloth. Removing the old anti foul may help before you start or else you will need to remove it anyway around each blister so that you have a clean feathered edge to laminate to, sounds like a pain if there are many blisters to remove.



That would allow you to address all of the blisters and then apply a proper barrier coat to keep the water out of contact with the polyester resin laminate that remains, else you will have more blisters to deal with as time goes on.

Hey, thanks for the response, I appreciate it.

Guess I've got a bunch of big ugly jobs in store, then, heh. Glorious glorious sanding.

[Heathenly Twins]

Originally Posted by Pandor

I know this doesn’t help, but the ideal situation would have been to grind out the blisters 2 years ago. After grinding out, you need to let the hull dry out prior to repairing. Two years on the hard would have done wonders.

Yeah well I didn't anticipate being away this long. Also unsure what do do about the external iron keels which need to be taken off and inspected and sealed. Live and learn, I suppose. 🤷*♂️

[Westcliffe01]

https://youtu.be/XA6sL3RRNEg

[skipgundlach]

Just a heads-up regarding 'drying out' a polyester hull:

The drying will be to get out the uncatalyzed resins leading to a non-laminate.

If you don't get that far, it is an invitation to more blisters.

WSM (water-soluble materials is the root of the issue.

To first dry out the hull you have to get rid of the WSMs.

Which is best done with a pressure wash, followed by a good rinse.

Grind back to solid and repeat until you no longer see any weeps.

THEN repair and re-barrier-coat and recoat antifoul...

There's a more fully explained and illustrated version of this topic under my name elsewhere on CF - search blister repair...

[Scrimshaw4]

Depending on the extent of blistering you might want to consider having your hull blasted to remove both the bottom paint, underlying barrier coat which failed where your blisters are (and will continue to fail), and the initial level of blister surface. Alternatively determine how deep your blisters go and to decide whether or not you'd be better off having the hull peeled. Either way the delamination caused by the blisters must be removed. Once the repair is completed you'll want to redo the entire hull with a barrier coat. I would highly recommend that you do NOT use Interprotect 2000. It has been known to fail within 5-8 years and then trap moisture. Sherman Williams and West both make better coatings. JMHO

[skipgundlach]

Originally Posted by Scrimshaw4

Sherman Williams and West both make better coatings. JMHO

Wholeheartedly agree on Sherwin-Williams, for both bottom paint and barrier coat...

right at 7.5 years on our bottom paint, still working but came out during a swamping in Isaias and took that opportunity to repair very small dings and recoat...

Two formulations of both types...