Hull blisters

[Gordonmc]

No, not a post from an invading osmosis afflicted BenJav owner!
My mahogany-on-oak double-ender had a major refit last winter which included a topside paint job. This involved replacment of nthe chain-plates and their through-hull bolts, raking seams and extensive fairing.
All has been well through the season, but last week I found a rash of blistering, especially in an area two feet aft of the stem.
The primer/undercoat was International with Interfill fairing and Blakes one-pot enamel.
The blisters are about 3mm in dia. and the paint is unbroken over them.
They appeared after a frost... could that have expanded any slight moisture under the paint to expand?
Any thoughts would be appreciated as I get ready for another repaint.

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[johnlilley]

Hi, I have often found with my own Hillyard that if the plastic cover has been in contact with the hull over the winter and condensation has formed behind it, it does raise moisture blisters in rashes where the contact has been continuous and direct. It does not seem to matter what quality paints are used in my experience. The only other reason I have come across is moisture that has crept down the structure via stem rabbets and the like which " surfaces". But you say yours is a long way from the stem rabbet or any other possible structural track.
John Lilley

<hr width=100% size=1>John Lilley, John Lilley & Associates, Web site www.seasurveys.co.uk for osmosis /timber problems

 

[Peterduck]

After a few years of topside painting, the paint film builds up thickness until any expansion/contractionof the paint overcomes the strength of the bond between paint and timber, and the paint comes away fom the wood. On my boat, this was happening over several square inches in any one place. The only cure was to burn off all the topsides paint and start again from scratch. I don't know if this is what is happening in your case, but it is something to be aware of.
Peter.

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