We were just talking about boardshaping amongst friend and one guy who has worked on the hull of his boat said you need to protect polyester hulls for osmosis.
To my knowledge and a quick act of googling,. we dont really do this, or do we?
I mean the hotcoat is our final layer (aside from an add. gloss coat).
We add parafine allowing us to sand the coat, but the parafine floats on top during hardening (right?) so I don’t see how we protect boards from osmosis.
is the effect so minimal it is not really something to take into account? But if it isn’t I have to assume general quick repairs stay vulnerable parts.
btw, I have summed some general assumptions I’ve gathered working on my first board about two years ago. I am about to start a second project. So point me out if anything I said is false.
thanks for caring, thanks for sharing
if osmosis does relates to boathulls made out of polyester i understand polyester can be perceived as a semi-permeable membrane by your given definition.
And if solutions are the key element here, i can only image the lack of moisture inside the board cancels the effect of osmosis here (true?)
if osmosis does relates to boathulls made out of polyester i understand polyester can be perceived as a semi-permeable membrane by your given definition.
And if solutions are the key element here, i can only image the lack of moisture inside the board cancels the effect of osmosis here (true?)
The post above is the correct definition of osmosis. You need two liquids of two different concentrations. The guy you talked to didn’t know what osmosis was and just threw out the term trying to define a problem. He was probably refering to the issue of fiberglass boat hulls “wicking” where water will travel along fibers into the hull. This is due to atmospheric pressure pushing down on the water as the hull displaces water and strands are exposed at the surface of the hull. Most hulls have layers of fiberglass mat and if there is exposure, they will wick like crazy. Surfboards with sanding coats and no gloss will also wick water but the weight gain is so minimal that the surfboard will usually break down due to surfing damage, pressure dings, etc. long before the board becomes water logged. Lost boards pre-leash days would sometimes wash up on the beach in Hawaii years later, brown as a coconut husk but still floating… Just my 2c
The guy you talked to didn’t know what osmosis was and just threw out the term trying to define a problem. Actually osmosis is the term used in polyester boat hulls . Surfteach has the correct discription for what is happening. I think it is on the West Systems or Epoxy works web sight that they explain why it is called Osmosis but no way am I going to take the time to look it up !
Thanks Ogre, that might be true, but they still have it wrong!! As a science guy, I run into this all the time, mis-use of terminology by someone trying to sell something, describe something, etc… Back in the day when I was working my way thru 8 years (non-continuous, eg. Vietnam) of college, one of my many part-time jobs was sanding boat hulls at a repair yard in Long Beach. You would have been shocked like me to see how many of the millionaire’s boats had dry mat in the hull! As you were grinding back the barnacles & worm holes, you would hit a patch and water and fiber would fly!! Sometimes so much water that you would be afraid it would short out the grinder… Ah, those were the days of itch…LOL
Actually, the term Osmotic blistering is an industry standard in boating. What it refers to (whether correctly named or not) is the ability of water to eventually enter a hull and gather in any air pocket or area of dry laminate. When you hit a blister with a grinder it is filled with a liquid that smells like rotten eggs and styrene. It is also why core hulls are usually put on the hill to dry after being in the water for several years. But even solid core hulls will wick moisture thru microscopic pores. We used to bag a badly blistered hull after stripping the bottom and let it bake in the sun for a couple of months. Moisture meter readings check the level of saturation every week. After about 3 months in the Florida sun the hull would be pretty dry again. Then a new epoxy resin barrier coat plus several layers of epoxy “micro plates” and ready for bottom paint and back in the water.
Given time and immersion water will enter any substance at least on a microscopic level.
I’m with Surfteach. I’m no science guy but logic tells me that wicking could only occur if weave is actually exposed, or in the case of a boat hull if the gelcoat is compromised by abrasion or intruded by barnicles or wormholes as he stated. We’ve all seen boards stored in the backyard fo 30 years and now have weave exposed and whited out from the resin being broken down from the elements. On those boards the fatal blow is from full delams from where the bond was compromised by UV exposure to the foam and extreme temperature changes every day over many years. I’ve never seen a board with water damaged foam from wicking, not even when weave is exposed, but only from open cracks, dings, pinholes, popped lap cuts, etc.
Your board will meet it’s end one day but it won’t be from osmosis or wicking, the problem only exists in theory and in practical terms it’s a non-issue. When making a board worry about pinholes, creating thin spots when sanding that will crack easily, overly aggressive razor blade pressure when cutting laps, etc.
I’d say don’t waste one more brain cell worrying about osmosis.
Edit: Just saw Johnny Fevers post above that makes perfect sense when talking about boats with mesh, gelcoats, and constant water emersion. These guys speak from experience there. Still, when it comes to surfboards fugetaboutit.
Gene is right. Boats and boards are completely different in the immersion aspect. Water will get in but it takes time. Boats are in the water 24/7 for their entire life. It takes years for blistering to occur in a good glass job. I’ve seen old Bertrams and Hatteras that were 30+ years old with few blisters. I’ve also seen boats less than 3 years old riddled with them. Porosity and resin content are key issues.
But again, that is in boats. Sitting in water. Always. Boards get hauled out and dried at the end of the day. Unless you have open wounds or seriously exposed cloth, don’t worry.
Thanks Johnny, for the update. I haven’t been around big boats for a long time so am really out of touch. When I was grinding away, core hulls were just a dream. I remember when the first hexcel boards came out. A rich friend bought one and the third time he took it to the beach in the back of his hot car, it blew up from the heat… Anyway, thanks for the newer info!!