At the end of last season I found 4 - 1" size water filled blisters. I cut them open to drain and dry out through the winter. In the spring The bumps were cleaned out, sanded and washed with acetone. Then they were filled with a 3M two part epoxy filler, sanded and covered with two coats of antifoul. So at haulout if there are another few bumps should I be concearned? Some say that to make life easier, just have the bottom epoxied by a professional and it should never have to be delt with for years. Comments?
Epoyx For hulls
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Interlux Barrier Coats
I've put barrier coats on four different boats. Each time I have used Interlux 2000E/2001E two part epoxy sealers to protect the bottom from blisters. Each time I was very satisfied with the out come. Once I used four coats of 2000/2001 and two coats of 3000/3001. Had to do with drying time or something. When the time is right I plan to do my 320. You must make certain that there are no blisters. If there are you must do what you did for the others last year. Just before the last coat was completely dry, I put the first coat of bottom paint on -- they meld together that way. Good luck. Paul
I've put barrier coats on four different boats. Each time I have used Interlux 2000E/2001E two part epoxy sealers to protect the bottom from blisters. Each time I was very satisfied with the out come. Once I used four coats of 2000/2001 and two coats of 3000/3001. Had to do with drying time or something. When the time is right I plan to do my 320. You must make certain that there are no blisters. If there are you must do what you did for the others last year. Just before the last coat was completely dry, I put the first coat of bottom paint on -- they meld together that way. Good luck. Paul
S
Steve D
Epoxy barrier coat in 1987
Jason: We purchased our H'31 in 1987. It had a barrier coat applied prior to it first launch. It has been pulled every 2-4 years since then and has NEVER had a single blister. Is this lucky or is it epoxy?
Jason: We purchased our H'31 in 1987. It had a barrier coat applied prior to it first launch. It has been pulled every 2-4 years since then and has NEVER had a single blister. Is this lucky or is it epoxy?
When to repair Individual Blisters
Gelcoat blisters can be a serious problem if left unattended. At some point, your hull may need extensive repair, including gelcoat removal and epoxy barrier coats as described in “Gelcoat Blisters: Diagnosis, Repair & Prevention” (West Systems #002-650). However, if you have isolated blisters and a manageable number to repair individually, it’s often recommended that you patch individual blisters and continue to use the boat until you determine the cause and extent of the problem. When does filling individual blisters make sense? 1. There are not many blisters on the hull. It is far easier and more sensible to fill a few blisters than to start peeling the gelcoat. Fill them and inspect each time you haul the boat. 2. The boat has not had blisters previously. It makes sense to repair the newly developed ones, then wait and see if more develop. These may be the only blisters that will ever form, or a small number may form each year that will require repair on an annual basis. 3. You just bought a used boat and have found a few blisters. Fill the individual blisters and investigate before doing a complete barrier coat. 4. You can improve ventilation and see if this solves the problem, making a complete barrier coat unnecessary. There appears to be an inverse relation between ventilation and blisters. More ventilation-fewer blisters. Fix individual blisters and then improve ventilation. 5. Funds are not available for a complete barrier coat. 6. The boat may not be worth the expense of doing a complete barrier coat repair. It costs a lot of money to have the job done by a yard, currently about $200 a foot. This may add up to more than the resale value of the boat. Additionally, costs of storing your boat out of the water just to dry and prepare the hull can add considerable expense. 7. You want to get your boat into the water so you can go boating. The time required to properly prepare and dry a hull may be longer than you want to wait. To do a full barrier coat, the boat will have to dry for a period of time. This can be accelerated with heat and dehumidifiers, but if you are depending on Mother Nature, drying time can be months.
Gelcoat blisters can be a serious problem if left unattended. At some point, your hull may need extensive repair, including gelcoat removal and epoxy barrier coats as described in “Gelcoat Blisters: Diagnosis, Repair & Prevention” (West Systems #002-650). However, if you have isolated blisters and a manageable number to repair individually, it’s often recommended that you patch individual blisters and continue to use the boat until you determine the cause and extent of the problem. When does filling individual blisters make sense? 1. There are not many blisters on the hull. It is far easier and more sensible to fill a few blisters than to start peeling the gelcoat. Fill them and inspect each time you haul the boat. 2. The boat has not had blisters previously. It makes sense to repair the newly developed ones, then wait and see if more develop. These may be the only blisters that will ever form, or a small number may form each year that will require repair on an annual basis. 3. You just bought a used boat and have found a few blisters. Fill the individual blisters and investigate before doing a complete barrier coat. 4. You can improve ventilation and see if this solves the problem, making a complete barrier coat unnecessary. There appears to be an inverse relation between ventilation and blisters. More ventilation-fewer blisters. Fix individual blisters and then improve ventilation. 5. Funds are not available for a complete barrier coat. 6. The boat may not be worth the expense of doing a complete barrier coat repair. It costs a lot of money to have the job done by a yard, currently about $200 a foot. This may add up to more than the resale value of the boat. Additionally, costs of storing your boat out of the water just to dry and prepare the hull can add considerable expense. 7. You want to get your boat into the water so you can go boating. The time required to properly prepare and dry a hull may be longer than you want to wait. To do a full barrier coat, the boat will have to dry for a period of time. This can be accelerated with heat and dehumidifiers, but if you are depending on Mother Nature, drying time can be months.
Individual Blister Repair
INDIVIDUAL & ISOLATED BLISTER REPAIR: 1. Open up blisters with a small abrasive tool like 3M's Rolock™ 2" diameter sanding disk with 60-grit sandpaper. Make sure that you have removed the entire blister, including the edges of the blister dome. 2. Wipe the cavity clean with an alcohol prep pad or paper towels that have been soaked in rubbing (isopropyl) alcohol. Be generous with the alcohol and be sure to change towels frequently so the contaminants are removed rather than spread. Repeat the alcohol wipe/allow to dry process until the laminate is dry to the touch. It is particularly important to repeat the alcohol-wipe process on blisters that were fluid filled at the time they were ground away. 3. Wet out the recently sanded and cleaned blister cavities with an unthickened mixture of 105/205 or 105/206 epoxy (* Note). Use 205 hardener if you are in a hurry. Allow this initial epoxy coat to gel slightly. This will lessen the likelihood of the thickened epoxy sliding out of the repair. If you don't have the time or the patience to wait for the epoxy to gel, you can wipe off most of the initial epoxy with dry paper towel or apply moderate heat to accelerate the epoxy's gel. 4. Fill the cavities with thickened epoxy (406 Colloidal Silica filler). (Note: This method is only for repairs that will not receive epoxy barrier coats prior to bottom painting.) Use enough filler to create a creamy non-sag paste that will feather out nicely with a plastic spreader or drywall taping knife. Avoid overfilling the cavities because 406 thickened epoxy is difficult to sand. On larger cavities where the epoxy may generate exotherm (heat buildup), add more filler to the mix to increase viscosity. The extra filler helps to resist sagging at elevated temperatures caused by exotherm. Allow the epoxy to cure. 5. Wet sand with 80-120-grit wet/dry sandpaper or wash with water (no soap, no ammonia) and sand dull with 100-grit sandpaper. If 105/205 epoxy has been used in warm conditions, sanding and bottom painting can be done later the same day. With slower hardener or in cooler temperatures, allow the epoxy to cure overnight. Notes: 1. All example part numbers are from WEST SYSTEM®. 2. See also WEST SYSTEMS publication #002-650 (“Gelcoat Blisters - Diagnosis, Repair & Prevention”)
INDIVIDUAL & ISOLATED BLISTER REPAIR: 1. Open up blisters with a small abrasive tool like 3M's Rolock™ 2" diameter sanding disk with 60-grit sandpaper. Make sure that you have removed the entire blister, including the edges of the blister dome. 2. Wipe the cavity clean with an alcohol prep pad or paper towels that have been soaked in rubbing (isopropyl) alcohol. Be generous with the alcohol and be sure to change towels frequently so the contaminants are removed rather than spread. Repeat the alcohol wipe/allow to dry process until the laminate is dry to the touch. It is particularly important to repeat the alcohol-wipe process on blisters that were fluid filled at the time they were ground away. 3. Wet out the recently sanded and cleaned blister cavities with an unthickened mixture of 105/205 or 105/206 epoxy (* Note). Use 205 hardener if you are in a hurry. Allow this initial epoxy coat to gel slightly. This will lessen the likelihood of the thickened epoxy sliding out of the repair. If you don't have the time or the patience to wait for the epoxy to gel, you can wipe off most of the initial epoxy with dry paper towel or apply moderate heat to accelerate the epoxy's gel. 4. Fill the cavities with thickened epoxy (406 Colloidal Silica filler). (Note: This method is only for repairs that will not receive epoxy barrier coats prior to bottom painting.) Use enough filler to create a creamy non-sag paste that will feather out nicely with a plastic spreader or drywall taping knife. Avoid overfilling the cavities because 406 thickened epoxy is difficult to sand. On larger cavities where the epoxy may generate exotherm (heat buildup), add more filler to the mix to increase viscosity. The extra filler helps to resist sagging at elevated temperatures caused by exotherm. Allow the epoxy to cure. 5. Wet sand with 80-120-grit wet/dry sandpaper or wash with water (no soap, no ammonia) and sand dull with 100-grit sandpaper. If 105/205 epoxy has been used in warm conditions, sanding and bottom painting can be done later the same day. With slower hardener or in cooler temperatures, allow the epoxy to cure overnight. Notes: 1. All example part numbers are from WEST SYSTEM®. 2. See also WEST SYSTEMS publication #002-650 (“Gelcoat Blisters - Diagnosis, Repair & Prevention”)
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