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Hull Blisters
I've dealt with hull blisters and have finally decided that they are
normally no big deal. I have never heard of hull failure from them and they seem to be simply a cosmetic problem. As far as drag goes, my fixed prop causes more drag. However, some ppl really hate em and go so far as to PEEEEEEEEELLLL their gelcoat (sounds really painful) dry the matting and re-gelcoat. I call this the Peel 'n Pray method cuz most offen the blisters return. Its just too hard to remove all the water from the matting even with heaters n such. Once, I took an electric heat gun and applied it about 4" from a blister (through the gelcoat)and was amazed at how much water came out of the blister (This was after 2 months of drying). Clearly, passive drying dont work. SO: Useless idea #3727 Peel only in narrow strips in a grid pattern to allow moisture to exit and apply heat to the grid squares. However, heating the glass is inefficient when you really want to heat the water. Instead, use microwaves which couple to polar molecules such as water and dont couple too well to the glass or resin (ie, you only heat the water). You could measure the microwave intensity inside the boat at different places as a function of time to determine dryness. The moisture would attenuate the waves and a dry hull would not. |
Hull Blisters
Parallax wrote:
I've dealt with hull blisters and have finally decided that they are normally no big deal. I have never heard of hull failure from them and they seem to be simply a cosmetic problem. As far as drag goes, my fixed prop causes more drag. However, some ppl really hate em and go so far as to PEEEEEEEEELLLL their gelcoat (sounds really painful) dry the matting and re-gelcoat. I call this the Peel 'n Pray method cuz most offen the blisters return. Its just too hard to remove all the water from the matting even with heaters n such. Once, I took an electric heat gun and applied it about 4" from a blister (through the gelcoat)and was amazed at how much water came out of the blister (This was after 2 months of drying). Clearly, passive drying dont work. SO: Useless idea #3727 Peel only in narrow strips in a grid pattern to allow moisture to exit and apply heat to the grid squares. However, heating the glass is inefficient when you really want to heat the water. Instead, use microwaves which couple to polar molecules such as water and dont couple too well to the glass or resin (ie, you only heat the water). You could measure the microwave intensity inside the boat at different places as a function of time to determine dryness. The moisture would attenuate the waves and a dry hull would not. Gosh, you have a LOT of ideas..... Because I think microwaves belong a long distance from people, I prefer the methods used 'round here. ALL depend upon a dry bilge, since water sitting in the bilge will keep the glass wet. The rankings are increasing level of severity. 1) Plastic draped over the hull to keep new water away. 2) A 100 watt bulb in the mostly-sealed cabin. 3) A dehumidifier in the mostly-sealed cabin, draining through an open through hull. 4) Plastic to the ground, a space heater under the hull 5) Plastic and a spacer taped closely to the hull and a vacuum pulled. Thus, I think #3727 should be filed as useless. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
Hull Blisters
One more... I used this and it worked great. http://www.hotvac.com/ I've
posted the summary a few times of all the work, but I'll post it again if anyone's interested. "Jere Lull" wrote in message ... Parallax wrote: I've dealt with hull blisters and have finally decided that they are normally no big deal. I have never heard of hull failure from them and they seem to be simply a cosmetic problem. As far as drag goes, my fixed prop causes more drag. However, some ppl really hate em and go so far as to PEEEEEEEEELLLL their gelcoat (sounds really painful) dry the matting and re-gelcoat. I call this the Peel 'n Pray method cuz most offen the blisters return. Its just too hard to remove all the water from the matting even with heaters n such. Once, I took an electric heat gun and applied it about 4" from a blister (through the gelcoat)and was amazed at how much water came out of the blister (This was after 2 months of drying). Clearly, passive drying dont work. SO: Useless idea #3727 Peel only in narrow strips in a grid pattern to allow moisture to exit and apply heat to the grid squares. However, heating the glass is inefficient when you really want to heat the water. Instead, use microwaves which couple to polar molecules such as water and dont couple too well to the glass or resin (ie, you only heat the water). You could measure the microwave intensity inside the boat at different places as a function of time to determine dryness. The moisture would attenuate the waves and a dry hull would not. Gosh, you have a LOT of ideas..... Because I think microwaves belong a long distance from people, I prefer the methods used 'round here. ALL depend upon a dry bilge, since water sitting in the bilge will keep the glass wet. The rankings are increasing level of severity. 1) Plastic draped over the hull to keep new water away. 2) A 100 watt bulb in the mostly-sealed cabin. 3) A dehumidifier in the mostly-sealed cabin, draining through an open through hull. 4) Plastic to the ground, a space heater under the hull 5) Plastic and a spacer taped closely to the hull and a vacuum pulled. Thus, I think #3727 should be filed as useless. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
Hull Blisters
Jere Lull wrote:
Because I think microwaves belong a long distance from people,... I think #3727 should be filed as useless. There may be valid reasons the idea won't work but a microwave phobia isn't one of them. |
Hull Blisters
"Keith" wrote in message ...
One more... I used this and it worked great. http://www.hotvac.com/ I've posted the summary a few times of all the work, but I'll post it again if anyone's interested. "Jere Lull" wrote in message ... Parallax wrote: I've dealt with hull blisters and have finally decided that they are normally no big deal. I have never heard of hull failure from them and they seem to be simply a cosmetic problem. As far as drag goes, my fixed prop causes more drag. However, some ppl really hate em and go so far as to PEEEEEEEEELLLL their gelcoat (sounds really painful) dry the matting and re-gelcoat. I call this the Peel 'n Pray method cuz most offen the blisters return. Its just too hard to remove all the water from the matting even with heaters n such. Once, I took an electric heat gun and applied it about 4" from a blister (through the gelcoat)and was amazed at how much water came out of the blister (This was after 2 months of drying). Clearly, passive drying dont work. SO: Useless idea #3727 Peel only in narrow strips in a grid pattern to allow moisture to exit and apply heat to the grid squares. However, heating the glass is inefficient when you really want to heat the water. Instead, use microwaves which couple to polar molecules such as water and dont couple too well to the glass or resin (ie, you only heat the water). You could measure the microwave intensity inside the boat at different places as a function of time to determine dryness. The moisture would attenuate the waves and a dry hull would not. Gosh, you have a LOT of ideas..... Because I think microwaves belong a long distance from people, I prefer the methods used 'round here. ALL depend upon a dry bilge, since water sitting in the bilge will keep the glass wet. The rankings are increasing level of severity. 1) Plastic draped over the hull to keep new water away. 2) A 100 watt bulb in the mostly-sealed cabin. 3) A dehumidifier in the mostly-sealed cabin, draining through an open through hull. 4) Plastic to the ground, a space heater under the hull 5) Plastic and a spacer taped closely to the hull and a vacuum pulled. Thus, I think #3727 should be filed as useless. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ Has anybody ever seen a case of hull failure due to blisters? I have never heard of such. |
Hull Blisters
Actually, I'm surprised that the racers haven't snapped to this yet.
Golf ball manufacturers sure did a long time ago. Don W. -- who is not a hydrodynamicist ;-) Larry W4CSC wrote: As to drag, a dimpled hull is FAR less drag than a smooth one that creates no eddy currents. Watch the jetski racers draggin' their race boats down the beach to roughen up the surface and break surface tension because they know it will go faster.....and it does. |
Hull Blisters
I believe that Jimmy Connors did it with a product from 3M called
"sharkskin." I also heard that the sailboat racing circuit had declared it illegal. "Don W" wrote in message . .. Actually, I'm surprised that the racers haven't snapped to this yet. Golf ball manufacturers sure did a long time ago. Don W. -- who is not a hydrodynamicist ;-) Larry W4CSC wrote: As to drag, a dimpled hull is FAR less drag than a smooth one that creates no eddy currents. Watch the jetski racers draggin' their race boats down the beach to roughen up the surface and break surface tension because they know it will go faster.....and it does. |
Hull Blisters
Parallax wrote:
Has anybody ever seen a case of hull failure due to blisters? I have never heard of such. I heard one story, but there were so many "heard it from"s that it could well be an urban (nautical?) legend. As I recall, there are some very close approximations on Dave Pascoe's site..... http://www.yachtsurvey.com/blisters.htm On the main site, I believe I saw a disintegrated powerboat that wasn't exactly blisters, but was a close relative. Could also have been in one of the BOAT/U.S. publications. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
Hull Blisters
Only one flaw in your arguement "drying the hull out generally doesn't work
ery well. What you are trying to get rid of is not only the moisture, but also the hydrscopic chemicals that are present. Just drying your boat out won't do the job. You need to draw out the chemicals and remove them. Other wise all that will happen is more moisture will be introduced into the laminate by the drying process. Unless the laminate is fully saturated, you'll do just as good a job by "peeling" and then washing the hul down with Alcohol or acetone. (your trying to strip those chmicals from the surface rather than attempt to "dry it out". Once that's been done you cna quickly recoat the hull. Don't waste your time waiting for it to "dry out" that will never happen. Pierre "Parallax" wrote in message om... I've dealt with hull blisters and have finally decided that they are normally no big deal. I have never heard of hull failure from them and they seem to be simply a cosmetic problem. As far as drag goes, my fixed prop causes more drag. However, some ppl really hate em and go so far as to PEEEEEEEEELLLL their gelcoat (sounds really painful) dry the matting and re-gelcoat. I call this the Peel 'n Pray method cuz most offen the blisters return. Its just too hard to remove all the water from the matting even with heaters n such. Once, I took an electric heat gun and applied it about 4" from a blister (through the gelcoat)and was amazed at how much water came out of the blister (This was after 2 months of drying). Clearly, passive drying dont work. SO: Useless idea #3727 Peel only in narrow strips in a grid pattern to allow moisture to exit and apply heat to the grid squares. However, heating the glass is inefficient when you really want to heat the water. Instead, use microwaves which couple to polar molecules such as water and dont couple too well to the glass or resin (ie, you only heat the water). You could measure the microwave intensity inside the boat at different places as a function of time to determine dryness. The moisture would attenuate the waves and a dry hull would not. |
Hull Blisters
Pierre,
What chemicals are you talking about? Regards, Ron |
Hull Blisters
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Hull Blisters
The uncured resins that are really the basis of blisters don't hold the
fiberglass together. They have to be heated to temperatures higher than the boiling point of water to get rid of. This can be a problem with cored hulls, where you might actually reach the glass transition temperature of the coring material before you get rid of the uncured resins. It's a common misconception that it's just water in the hull. It's really the acidic non-cured resins (which are hydroscopic in nature). See: http://www.hotvac.com/ http://www.daviscoltd.com/nams/Docum...er_Report.html http://www.yachtsurvey.com/blisters.htm http://www.marinesurvey.com/yacht/BlisterRepairFail.htm http://www.osmosisinfo.com/ ....to learn more about blistering, it's causes and repairs. "Parallax" wrote in message om... (Ron Thornton) wrote in message ... Pierre, What chemicals are you talking about? Regards, Ron With the microwave idea, I would not apply enough power to turn the water to steam, but enough to heat it to cause evaporation from the strips where the gelcoat has been peeled. This would cause the water from furhter from the strips to migrate (with the dissolved chemicals) to the peeled strips. Perhaps after the hull had dried enough, you might peel another inch on either side of the strips to get rid of more of the chemicals. HOWEVER, I am doubtful of ANY process getting rid of enouigh of these chemicals to matter since these chemicals are part of the resin holding the fibreglas together. The best bet may be to either not worry about blisters or to get rid of the water and then encapsulate the hull in a membrane that will not allow water penetration. Once again, has anyone heard of any real hull failures from osmotic blisters? |
Hull Blisters
Thanks Keith,
That explains a lot. Regards, Ron |
Hull Blisters
"Keith" wrote in message ...
The uncured resins that are really the basis of blisters don't hold the fiberglass together. They have to be heated to temperatures higher than the boiling point of water to get rid of. This can be a problem with cored hulls, where you might actually reach the glass transition temperature of the coring material before you get rid of the uncured resins. It's a common misconception that it's just water in the hull. It's really the acidic non-cured resins (which are hydroscopic in nature). See: http://www.hotvac.com/ http://www.daviscoltd.com/nams/Docum...er_Report.html http://www.yachtsurvey.com/blisters.htm http://www.marinesurvey.com/yacht/BlisterRepairFail.htm http://www.osmosisinfo.com/ ...to learn more about blistering, it's causes and repairs. "Parallax" wrote in message om... (Ron Thornton) wrote in message ... Pierre, What chemicals are you talking about? Regards, Ron With the microwave idea, I would not apply enough power to turn the water to steam, but enough to heat it to cause evaporation from the strips where the gelcoat has been peeled. This would cause the water from furhter from the strips to migrate (with the dissolved chemicals) to the peeled strips. Perhaps after the hull had dried enough, you might peel another inch on either side of the strips to get rid of more of the chemicals. HOWEVER, I am doubtful of ANY process getting rid of enouigh of these chemicals to matter since these chemicals are part of the resin holding the fibreglas together. The best bet may be to either not worry about blisters or to get rid of the water and then encapsulate the hull in a membrane that will not allow water penetration. Once again, has anyone heard of any real hull failures from osmotic blisters? It seems that most blisters occur between the gelcoat and "skincoat" of fibreglas or betwen the skincoat and the actual structural matting. In most cases they have no effect on structural strength since the skin coat is only there to prevent "print through" of the underlying matting that does provide structure. These blisters are almost always due to poor wetting of the skincoat with resin or use of poor quality resin that causes lack of adhesion of the skincoat to the matting ( I am paraphrasing from one of the websites suggested by an above poster, you oughta read it, cuz its got good material). Most gelcoat repairs fail, even those done by professionals. Since blisters are rarely structural, the best course may be to simply live with them but ascertain how your hull is built. So, here is another idea for blisters: Useless idea #3729 Since blisters are caused by poor wetting of the skincoat, why not make tiny holes in a large blister and inject very thin epoxy into the blisters (after forcing as much water out as you can) and then apply pressure to cause it to re-conform to the hull as much as possible forcing epoxy out the many holes. There are also materials (think superglue) that polymerise in the presence of water, maybe inject them. Since the professional "repairs" ussually fail, I feel justified in suggesting ideas. |
Hull Blisters
Parallax wrote:
So, here is another idea for blisters: Useless idea #3729 AHAH! CAUGHT you re-using a number! This should be 3730 or so ;-) Since blisters are caused by poor wetting of the skincoat, why not make tiny holes in a large blister and inject very thin epoxy into the blisters (after forcing as much water out as you can) and then apply pressure to cause it to re-conform to the hull as much as possible forcing epoxy out the many holes. There are also materials (think superglue) that polymerise in the presence of water, maybe inject them. Might be an idea, but I just found out that improperly wetted out glass in our new anchor well did NOT wet out when I put additional on top. I suspect what little resin was there prevented new resin being absorbed. In my case, it's of no significance since we put a couple of more layers of properly wetted out glass cloth over for strength and it's not going to be a normally-wet area, so blisters will not be a factor. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
Hull Blisters
Well, because it's easier to just grind out the blister and relaminate. Much
more effective that trying to get that stuff out on a blister by blister basis. "Parallax" wrote in message snip So, here is another idea for blisters: Useless idea #3729 Since blisters are caused by poor wetting of the skincoat, why not make tiny holes in a large blister and inject very thin epoxy into the blisters (after forcing as much water out as you can) and then apply pressure to cause it to re-conform to the hull as much as possible forcing epoxy out the many holes. There are also materials (think superglue) that polymerise in the presence of water, maybe inject them. Since the professional "repairs" ussually fail, I feel justified in suggesting ideas. |
Hull Blisters
x-no-archive:yes
Jere Lull wrote: Parallax wrote: So, here is another idea for blisters: Useless idea #3729 AHAH! CAUGHT you re-using a number! This should be 3730 or so ;-) Since blisters are caused by poor wetting of the skincoat, why not When we hauled our boat for the pre-purchase survey, the surveyor found blisters, which he showed to me. I saw them. We've never seen those blisters since on any subsequent haulout. They've disappeared. This was a (at the time) 19 year old boat. So I'm not sure all blisters are caused by poor wetting of the skincoat. Bob thinks that the ones we saw were in the paint. make tiny holes in a large blister and inject very thin epoxy into the blisters (after forcing as much water out as you can) and then apply pressure to cause it to re-conform to the hull as much as possible forcing epoxy out the many holes. There are also materials (think superglue) that polymerise in the presence of water, maybe inject them. Might be an idea, but I just found out that improperly wetted out glass in our new anchor well did NOT wet out when I put additional on top. I suspect what little resin was there prevented new resin being absorbed. In my case, it's of no significance since we put a couple of more layers of properly wetted out glass cloth over for strength and it's not going to be a normally-wet area, so blisters will not be a factor. grandma Rosalie S/V RosalieAnn, Leonardtown, MD CSY 44 WO #156 http://home.mindspring.com/~gmbeasley/id2.html |
Hull Blisters
Rosalie B. wrote:
When we hauled our boat for the pre-purchase survey, the surveyor found blisters, which he showed to me. I saw them. We've never seen those blisters since on any subsequent haulout. They've disappeared. This was a (at the time) 19 year old boat. So I'm not sure all blisters are caused by poor wetting of the skincoat. Bob thinks that the ones we saw were in the paint. My perception is that any "blisters" that don't penetrate through the basic layup are inconsequential. On the Tanzer list, we've had a number of complaints of "blisters" at the waterline, all less than a dime's size; almost all less than a quarter inch. As I read the descriptions, they were simply gel coat expanding and contracting differently than the substrate. That sort of thing is no problem; I know of no cases that got worse than that. Blisters extend into the hull's structure. The "blisters" that only affect the surface are of little consequence. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
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