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Microwaves to dry boat hulls
Say you want to drive the moisture out of gelcoat. I've used a heat
gun to do it and was surprised at how much water came out. So, what would a high power microwave unit do? Water absorbs the microwaves much better than the polyester so it would get hot and come out. This would avoid the months of waiting for a hull to dry if you are repairing blisters (a real scam as blisters are not a real problem). |
Microwaves to dry boat hulls
Probably would work well, but I know of no way to do this safely. You would be irradiating the world.
Steve "Frogwatch" wrote in message ... Say you want to drive the moisture out of gelcoat. I've used a heat gun to do it and was surprised at how much water came out. So, what would a high power microwave unit do? Water absorbs the microwaves much better than the polyester so it would get hot and come out. This would avoid the months of waiting for a hull to dry if you are repairing blisters (a real scam as blisters are not a real problem). |
Microwaves to dry boat hulls
On Wed, 24 Mar 2010 20:20:45 -0700 (PDT), Frogwatch
wrote: Say you want to drive the moisture out of gelcoat. I've used a heat gun to do it and was surprised at how much water came out. So, what would a high power microwave unit do? Water absorbs the microwaves much better than the polyester so it would get hot and come out. This would avoid the months of waiting for a hull to dry if you are repairing blisters (a real scam as blisters are not a real problem). Some years ago I read, in one of the boating magazines, about a guy that had invented an innovative method of drying a hull. He removed the door from a micro-wave oven and bypassed the "door-open" safety switch. Placed the oven face down on the deck and turned on the power. I never read anything more about the method and have visions of him heating the saturated deck core to the point that steam was generated and the resultant upheaval. Water when heated turns to steam and I can assure you that the steam will come out :-) Cheers, Bruce |
Microwaves to dry boat hulls
On Mar 25, 7:58*am, wrote:
On Wed, 24 Mar 2010 20:20:45 -0700 (PDT), Frogwatch wrote: Say you want to drive the moisture out of gelcoat. *I've used a heat gun to do it and was surprised at how much water came out. So, what would a high power microwave unit do? *Water absorbs the microwaves much better than the polyester so it would get hot and come out. *This would avoid the months of waiting for a hull to dry if you are repairing blisters (a real scam as blisters are not a real problem). "some" blisters are not a problem. Who said anything about being safe? Seriously, you could put an absorber on the far side to stop the waves or even a metal plate (thin foil) to reflect em back to be more efficient. |
Microwaves to dry boat hulls
Bruce writes:
On Wed, 24 Mar 2010 20:20:45 -0700 (PDT), Frogwatch wrote: Say you want to drive the moisture out of gelcoat. I've used a heat gun to do it and was surprised at how much water came out. So, what would a high power microwave unit do? Water absorbs the microwaves much better than the polyester so it would get hot and come out. This would avoid the months of waiting for a hull to dry if you are repairing blisters (a real scam as blisters are not a real problem). Some years ago I read, in one of the boating magazines, about a guy that had invented an innovative method of drying a hull. He removed the door from a micro-wave oven and bypassed the "door-open" safety switch. Placed the oven face down on the deck and turned on the power. Innovative and dangerous. I never read anything more about the method and have visions of him heating the saturated deck core to the point that steam was generated and the resultant upheaval. Water when heated turns to steam and I can assure you that the steam will come out :-) Heat the laminate + water quick enough and you create blisters. This is one of the quality assurance tests of printed circuit boards. Too much moisture (which is much, much less than found in any boat laminate) or poor laminating quality (still much better than you hand layup boat laminate) will cause blisters. OK, that test involves much higher temperatures than what you are likely to subject your laminates to. Bear in mind that high temperatures degrade laminates. Why not try the kind of equipment used to dry out buildings that got drenched one way or another? It may not be as innovative but also much less likely to damage your boat or indeed yourself. /Martin |
Microwaves to dry boat hulls
On Thu, 25 Mar 2010 11:04:49 -0400, I am Tosk
wrote: In article , says... On Wed, 24 Mar 2010 20:20:45 -0700 (PDT), Frogwatch wrote: Say you want to drive the moisture out of gelcoat. I've used a heat gun to do it and was surprised at how much water came out. So, what would a high power microwave unit do? Water absorbs the microwaves much better than the polyester so it would get hot and come out. This would avoid the months of waiting for a hull to dry if you are repairing blisters (a real scam as blisters are not a real problem). Some years ago I read, in one of the boating magazines, about a guy that had invented an innovative method of drying a hull. He removed the door from a micro-wave oven and bypassed the "door-open" safety switch. Placed the oven face down on the deck and turned on the power. I never read anything more about the method and have visions of him heating the saturated deck core to the point that steam was generated and the resultant upheaval. Water when heated turns to steam and I can assure you that the steam will come out :-) Cheers, Bruce Won't vacuum boil out water vapor? Scotty Well, yes I suppose that you are correct in that a decrease in pressure results in water vaporizing at a lower temperature, however suspect that the evaporated vapor has far less energy then water vapor that is produced by heating. At least it is difficult to put a pot of water out in the sun and power a steam engine with it :-) I suspect that the O.P. was trying to devise a method to laminate layers and get a chemical bond between layers. In practice no one who works in the trade seems to consider this a problem. The worry about laminating epoxy structures is always amine blush and cleaning it prior to laminating the next layer. There are epoxies that do not produce blush but I have never seen them used in actual practice. I suspect it is a matter of cost. It would be interesting to see some testing of laminated structures produced by continuous laminating, I.e., not letting the epoxy set up between layers, and the same structure produced by waiting until each lamination hardened and then sanding with coarse paper before applying the next layer. Cheers, Bruce |
Microwaves to dry boat hulls
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Microwaves to dry boat hulls
Frogwatch wrote:
Say you want to drive the moisture out of gelcoat. I've used a heat gun to do it and was surprised at how much water came out. So, what would a high power microwave unit do? Water absorbs the microwaves much better than the polyester so it would get hot and come out. This would avoid the months of waiting for a hull to dry if you are repairing blisters (a real scam as blisters are not a real problem). A few years ago there was a system developed in Europe that used a combination of heat and vacuum to dry out laminates. I see it is now available in the USA. Take a look at: http://www.hotvac.com/testimonial/default.aspx Brian C |
Microwaves to dry boat hulls
I do not think Microwave heating to eliminate moisture in fiberglass is practical. The oven in a microwave unit is a reflective
cavity. You would have to have a reflective chamber the size of the boat and a several megawatts of RF to be effective. There would be dead spots and spots of excessive heating, just like in a microwave oven. Even if you would do this, you would still have to provide a means of absorbing the moisture generated in the chamber's air. (Basic gas laws and equilibrium apply) There are more practical ways of achieving this. It is important to understand the problem in order to find a solution. No construction material lasts forever. They each have their disadvantages and advantages and a finite life. The failure mode of all fiber based plastics are UV driven disintegration and osmosis. Osmosis is the wicking effect all fibers have when exposed to a liquid, which causes hydraulic delamination at the weakest bond. Although FG is not waterproof, it is not readily permeable either and there is your dilemma. Once moisture has invaded the material, it is next to impossible to get it all out.Even though fiberglass boat construction has been around since the 50's, there are not many boats still around that old. The cost of FG hull maintenance is only exceeded by wood. All other materials have a better TCO (total cost of ownership). I'm sure that statement will generate some flames, but it is observable and self evident, Steve. |
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