Lizzie_B
Well-Known Member
Is a fibreglass boat that has spent its entire life in fresh water more or less likely to suffer from osmosis? If there is any difference, what factors cause it?
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Fresh Water and Osmosis
- Thread starter Lizzie_B
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BrendanS
Well-Known Member
Fresh water is worse than salt.
The reasons require a good understanding of chemistry. Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration.
In laymans terms, movement of water from where the water is relatively pure to where it has lots of salts or other chemicals - the water tries to find a balance by diluting the salt . So in fresh water, the water moves into the hull, where there are water soluble chemicals more easily, than when in sea water where there are salts in the water already.
Bit of a difficult concept to explain without doing a bit of chemistry around it.
Other things will affect it, like the temperature. Heat makes it easier for the water to migrate
Sorry, not a brilliant answer, but tried to keep complicated technical terms out.
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The reasons require a good understanding of chemistry. Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration.
In laymans terms, movement of water from where the water is relatively pure to where it has lots of salts or other chemicals - the water tries to find a balance by diluting the salt . So in fresh water, the water moves into the hull, where there are water soluble chemicals more easily, than when in sea water where there are salts in the water already.
Bit of a difficult concept to explain without doing a bit of chemistry around it.
Other things will affect it, like the temperature. Heat makes it easier for the water to migrate
Sorry, not a brilliant answer, but tried to keep complicated technical terms out.
<hr width=100% size=1>Me transmitte sursum, caledoni
More.
Think of it like electricity, the osmotic potential difference is higher.
Also read the latest YM where in the what the surveyor says article a 5 year old Hanse that lived on Lake Windermere is found to have some osmosis.
<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by jonjo on 17/06/2004 00:35 (server time).</FONT></P>
Think of it like electricity, the osmotic potential difference is higher.
Also read the latest YM where in the what the surveyor says article a 5 year old Hanse that lived on Lake Windermere is found to have some osmosis.
<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by jonjo on 17/06/2004 00:35 (server time).</FONT></P>
Jools_of_Top_Cat
Well-Known Member
hmmm, my hot tub should really be suffering then. It is at a constant 37° and always full. Yet after 4 years the 'hull' integrity is sound, still looks new.
Maybe boat builders could learn a thing or two from other industries?
<hr width=100% size=1>Julian
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Maybe boat builders could learn a thing or two from other industries?
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MainlySteam
Well-Known Member
<<<Maybe boat builders could learn a thing or two from other industries?>>>
Quite likely.
Also marine instrument makers might too learn from other industries if anyone read my post regarding my electronic car key with push buttons, battery, etc that spent near a week under 4 metres of water in the marina and when finally recovered it was perfectly dry inside and not a thing wrong with it.
John
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Quite likely.
Also marine instrument makers might too learn from other industries if anyone read my post regarding my electronic car key with push buttons, battery, etc that spent near a week under 4 metres of water in the marina and when finally recovered it was perfectly dry inside and not a thing wrong with it.
John
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BrendanS
Well-Known Member
The stuff that hot tubs are made out of don't have to take the stresses that boats hulls do. hence made out of different layup, and designed not to have osmosis, rather than to take pounding
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StugeronSteve
Well-Known Member
When we moved into our house there was a rather expensive, and enormous, GRP corner bath in the bathroom. It was covered in osmotic blisters and I assume had not been left full of water on a continuous basis.
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ParaHandy
Well-Known Member
skint, we had to rent our first house (in whitley bay) and you could only have a bath after giving the landlady 12 hours notice so ... once filled with (tepid) water large blisters began to rise everywhere. we burst 'em. what fun but got chased out by the auld witch ...
the bath had been painted over with gloss paint ....
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the bath had been painted over with gloss paint ....
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Norrsken
New Member
Thats true, I used to run a factory that made them, baths I mean. We initially had a lot of trouble because dealers just filled them up and left them. We learned to use better materials and got over the problem. I guess that it is the same with boats and as always you are likely in the end to get what you paid for.
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BrendanS
Well-Known Member
What did you do to overcome the problems?
<hr width=100% size=1>Me transmitte sursum, caledoni
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davidhand
Well-Known Member
Yes that would follow the general concensus here in the States. Where I have read in several articles by surveyors that the worst boats are great lakes boats, followed by boats from Florida. I should be OK here in northern California where the water temperature is low 50's F.
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