We were sitting around having coffee at the yacht club when the question arose about blisters on the hull. One theory was that it was caused amongts other things,that electrolisis in the water(due to power cords lying in the water)caused blisters. I am having a hard time buying in to that theory and if so what is the science behind it. I have always believed it was simply osmosis.Hypotonic solution moving towards hypertonic solution? Any of you science guys/girls have an opinion it would be greatly appreciated.Where I live it is to cold to sail so we drink coffee and discuss great things about our boats. Regards Ron
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D J
You're right
The thinking is with you. The rest of the discussion usually moves to do product and its density and resistence to osmosis.
The thinking is with you. The rest of the discussion usually moves to do product and its density and resistence to osmosis.
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John Dawson
Don Casey says
and I quote "Water-soluble chemicals inside the laminate exert an osmotic pull on water outside, and some water molecules find a way though" the gel coat. "The water molecules aren't squirted back out the way they came in because they have combined with the attracting chemicals into a solution with a larger molecular structure. Instead, the pressure pushes the covering laminate into a dome - a blister." Whether an electrical curent will facilitate the osmotic process, I have no idea.
and I quote "Water-soluble chemicals inside the laminate exert an osmotic pull on water outside, and some water molecules find a way though" the gel coat. "The water molecules aren't squirted back out the way they came in because they have combined with the attracting chemicals into a solution with a larger molecular structure. Instead, the pressure pushes the covering laminate into a dome - a blister." Whether an electrical curent will facilitate the osmotic process, I have no idea.
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Ed
Not sure how/why electrical cords would enter into the issue of osmosis. Baically everything in nature wants to come to equilbrium. Thus the term "nature abhorts a vacuum." If you were to have a solution with no salt and one with salt the tendency of nature would be to equilibrate the solution by having the fresh balance the salt. Soooooo - if the fresh water were on the side of the hull (like left in the process of forming) the salt water would like to enter the fresh to a point that the salt content would be equal. If that makes blisters (not at all sure what does) then that is the process that they form. Used to be a Chem E. Not great at that so became a consultant and eventually a proffesor of another subject. Hope this helps around the coffee table.
Some past research.
Ron: Maybe they are adding something to their coffee that you are not adding to yours? Here are a bunch of links about blisters. It is sort of a bunch of 'expert' links on the subject. http://archive.sailboatowners.com/archive/archivepview.tpl?sku=2001303062929.82&forumabr=as&fno=122&_ptitle=ptitle%20rtitle&_pname=pname&&model=none&forum=none&andor=wa&keyword=blister%20dion&pr=p&ssite=HOW&srt=pdate&start=1&max=20
Ron: Maybe they are adding something to their coffee that you are not adding to yours? Here are a bunch of links about blisters. It is sort of a bunch of 'expert' links on the subject. http://archive.sailboatowners.com/archive/archivepview.tpl?sku=2001303062929.82&forumabr=as&fno=122&_ptitle=ptitle%20rtitle&_pname=pname&&model=none&forum=none&andor=wa&keyword=blister%20dion&pr=p&ssite=HOW&srt=pdate&start=1&max=20
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Jim willis
Its due to a few things including......
unicorporated resin comonents. I spent a while distilling all this down to a little "essay" a while back. You can find it and related postings about gelcoat repair, different resin types etc on the Gelcoat and Plastics Forum (this site) - Fiberglass Trilogies I II and III The links that Steve gave are also great. I just tried to make some sort of synopsis, particularly in the "mythology" department. Thanks Jim W
unicorporated resin comonents. I spent a while distilling all this down to a little "essay" a while back. You can find it and related postings about gelcoat repair, different resin types etc on the Gelcoat and Plastics Forum (this site) - Fiberglass Trilogies I II and III The links that Steve gave are also great. I just tried to make some sort of synopsis, particularly in the "mythology" department. Thanks Jim W
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David
Blisters
I attended a Bruce Pfund seminar and spoke with him at the IBEX (International Boatbuilders' Exhibition & Conference) show in Ft. Lauderdale last month. I think there are very few people that know more than Bruce about hull construction and blisters. Anyone interested might want to go his site. http://www.bpspecialprojects.com/surveyphotos.html
I attended a Bruce Pfund seminar and spoke with him at the IBEX (International Boatbuilders' Exhibition & Conference) show in Ft. Lauderdale last month. I think there are very few people that know more than Bruce about hull construction and blisters. Anyone interested might want to go his site. http://www.bpspecialprojects.com/surveyphotos.html
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