Rudder osmosis blisters

[andylipsberg]

I have discovered some osmosis blisters, the biggest ones I have sanded out, but reluctant to work on all the small ones.

All small white spots what you see eventually have water. What would recommend, shall I proceed with sanding to laminate or work on the big ones only?

It’s basically lot of gelcoat off on the sides. Or it should be less aggressive treatment?

Looks to me that conditions on gelcoat application in the factory where not met.

Rudder itself is dry, I have hole and nothing went out.

 

[Fr J Hackett]

Sand, fair and fill with a thickened epoxy then sand and fair followed by primer and antifoul if as you say there is no water in the rudder.

 

[Stemar]

It depends where the blisters are. If they're under the gelcoat, it's going to be a big job to get rid, fair and finish. If they're only under a layer of paint/antifoul, sand that off add a few coats of Gelshield if you're feeling energetic then antifoul.

If you're not feeling very energetic, just do the last step

 

[andylipsberg]

It depends where the blisters are. If they're under the gelcoat, it's going to be a big job to get rid, fair and finish. If they're only under a layer of paint/antifoul, sand that off add a few coats of Gelshield if you're feeling energetic then antifoul.

If you're not feeling very energetic, just do the last step

They are under gelcoat unfortunately, I started to sand those parts already

 

[ChromeDome]

Regardless of being osmosis or delamination blisters, I'd do what you do, prime, fill, sand and reshape the surface.

Then prepare for anti-fouling (specific primer as per the instrctions on the tin, then AF).

And remind myself that despite all the buzz about osmosis, I have not heard of a single boat sinking due to it.

 

[srm]

If the rudder has a foam core this could be saturated, but nothing will run out if you drill a hole. In this case the problem will be ongoing so just fill and fair the bigger holes. You will eventually fill the smaller ones as they grow. As long as the rudder does not get to the stage where it starts to loose its integrity its not a big deal.
I had this on a Prout catamaran and just lived with it. Slight problem when I sold it as buyer tried to leaver the price down.

 

[andylipsberg]

Regardless of being osmosis or delamination blisters, I'd do what you do, prime, fill, sand and reshape the surface.

Then prepare for anti-fouling (specific primer as per the instrctions on the tin, then AF).

An remind myself that despite all the buzz about osmosis, I have not heard of a single boat sinking due to it.

Maybe orcas hit just osmotic rudders. Just kidding. Thanks for the input.

 

[ChromeDome]

.. buyer tried to leaver the price down.

We're all looking for a leverage to negotiate a better price.
Preferably by claiming a disadvantage that has no bearing on the value you get - only on the price you pay