My original 1978 aluminum water tank has been corroded at one end by a long neglected (not by me) chain plate leak. Now that the leak is repaired, I need to address the corrosion on the end of the tank. One of the local repair guys suggested grinding off as much corrosion as possible and then applying zinc chromate to the clean surface. He said it was very caustic and not easy to handle. I am unfamiliar with this chemical. My thought was to grind and then encapsulate in fiberglass. Any comments or other ideas?
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Peggie Hall/Head Mistress
Replace the tank, David
20-25 years is about the average lifespan of aluminum water tanks, and your tank is there. You only know about the corrosion on the outside...the inside is likely to be pitted and ready to spring new leaks any time. Encapsulating in fiberglass will be more effort and expense than a new tank and leave you or the next owner with a worse problem: water soaked rotting fiberglass AND a tank that has to be replaced.
20-25 years is about the average lifespan of aluminum water tanks, and your tank is there. You only know about the corrosion on the outside...the inside is likely to be pitted and ready to spring new leaks any time. Encapsulating in fiberglass will be more effort and expense than a new tank and leave you or the next owner with a worse problem: water soaked rotting fiberglass AND a tank that has to be replaced.
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Ron
Dave
I keep my boat at Portofino in Clear Creek. Would like to discuss water tanks with you. I need to change mine also and will be starting the project in about a week. How can I get in touch?? Ron/KA5HZV
I keep my boat at Portofino in Clear Creek. Would like to discuss water tanks with you. I need to change mine also and will be starting the project in about a week. How can I get in touch?? Ron/KA5HZV
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Sam Lust
Zinc chromate
Zinc chromate is a paint, or at least that's how I know it. It is applied as primer on aluminum prior to regular paint, and will enable paint to stick to chrome plating. (I have used on both.) It tends to be difficult to find. Zinc phosphate on the other hand can be found and is nearly as good. I found some at a marine supply store and a local hardware store. Very nasty olive green color, but it does the job - similar to tthe orriginal color of your tank. Not tough to use at all. Sand lightly and paint immediately while the metal is still shiny. East to determine if the tank is going. Cut a hole in it for a Beckson port. I use clear because it allows me to check water level easily. Scrub and rinse completely I use a shop vac to draw out rinse water) and inspect all surfaces thoroughly. You may need light and a miror. Corrosion might be visable a surface level anywhere water has remained standing for long periods. (my experience) Probably the first place you'd experience problems would be the pickup tube. Mine developed holes or cracking, probably at the weldment. I just abandoned it and dropped in a new PVC plastic pipe one, ty-wrappint to the old pipe Works just dandy. Other than that mine seems ready to go a number of years yet. I almost wish it would hole through so I'd have a good reason to replace my single 50 gal two with Vetus bags mounted a bit aft, and I'd get to figure out how to cut the thing ou without cutting up the v-berth where it's mounted. I'd like more capacity and to get the weight closer to the keel.
Zinc chromate is a paint, or at least that's how I know it. It is applied as primer on aluminum prior to regular paint, and will enable paint to stick to chrome plating. (I have used on both.) It tends to be difficult to find. Zinc phosphate on the other hand can be found and is nearly as good. I found some at a marine supply store and a local hardware store. Very nasty olive green color, but it does the job - similar to tthe orriginal color of your tank. Not tough to use at all. Sand lightly and paint immediately while the metal is still shiny. East to determine if the tank is going. Cut a hole in it for a Beckson port. I use clear because it allows me to check water level easily. Scrub and rinse completely I use a shop vac to draw out rinse water) and inspect all surfaces thoroughly. You may need light and a miror. Corrosion might be visable a surface level anywhere water has remained standing for long periods. (my experience) Probably the first place you'd experience problems would be the pickup tube. Mine developed holes or cracking, probably at the weldment. I just abandoned it and dropped in a new PVC plastic pipe one, ty-wrappint to the old pipe Works just dandy. Other than that mine seems ready to go a number of years yet. I almost wish it would hole through so I'd have a good reason to replace my single 50 gal two with Vetus bags mounted a bit aft, and I'd get to figure out how to cut the thing ou without cutting up the v-berth where it's mounted. I'd like more capacity and to get the weight closer to the keel.
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David Popken
Contact Numbers
Try my office number 713-426-5900 or cell 713-705-2515. I am at Blue Dolphin Marina.
Try my office number 713-426-5900 or cell 713-705-2515. I am at Blue Dolphin Marina.
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David Popken
How to Replace?
Tank is under the starboard setee and would require some fiberglass cutting to remove and replace. maybe it could be cut up in place and then a bladder type replacement installed without cutting fiberglass. Any thoughts?
Tank is under the starboard setee and would require some fiberglass cutting to remove and replace. maybe it could be cut up in place and then a bladder type replacement installed without cutting fiberglass. Any thoughts?
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John
Cut the Glass
Cut the settee top. I just did this about 2 weeks ago. I agonized over whether to cut the tank out and replace with flexible, or cut the fiberglass and replace with "hard" tank. Decieded to cut the tank out. After wasting a lot of time trying to get good access, I ended up getting frustrated and just cut the "bridge" between the 2 access panels on the top of the settee. Took about 5 min, and then another 20 to work the tank out through the hole. Some people have chosen to reglass the piece back in, I took a piece of 3/4 in plywood, and bolted it ( 3 bolts ) to either side of the opening. Very strong, and allows me to get back in should I ever need to. Also ( most importantly ) I didn't have to mess with fiberglass. It took about an hour to get the wood sized, and bolted in. BTW, I ended up using a flexible water tank anyway....
Cut the settee top. I just did this about 2 weeks ago. I agonized over whether to cut the tank out and replace with flexible, or cut the fiberglass and replace with "hard" tank. Decieded to cut the tank out. After wasting a lot of time trying to get good access, I ended up getting frustrated and just cut the "bridge" between the 2 access panels on the top of the settee. Took about 5 min, and then another 20 to work the tank out through the hole. Some people have chosen to reglass the piece back in, I took a piece of 3/4 in plywood, and bolted it ( 3 bolts ) to either side of the opening. Very strong, and allows me to get back in should I ever need to. Also ( most importantly ) I didn't have to mess with fiberglass. It took about an hour to get the wood sized, and bolted in. BTW, I ended up using a flexible water tank anyway....
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John renfro
repair
hello david, it think it would be better to replace the tank. Depending on the depth of the corrosion, pitting can weaken the body in that area, surface is nothing to worry about,clean it off and leave it. If you need zink chromate, west marine has it in spray cans. I don't think it is a particularly caustic, it is used by general aviation to prime aircraft for painting and, without painting, as a corrosion preventative. John john
hello david, it think it would be better to replace the tank. Depending on the depth of the corrosion, pitting can weaken the body in that area, surface is nothing to worry about,clean it off and leave it. If you need zink chromate, west marine has it in spray cans. I don't think it is a particularly caustic, it is used by general aviation to prime aircraft for painting and, without painting, as a corrosion preventative. John john
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David Popken
Cut It?
I can cut between both hatches as you had to do, but the other problem I have is that the tank extends beyond the hatches in all four directions. I think I can cut it up with a sawzall and then compress it down before removing. I'm also wondering if your tank was glassed in place. I think mine is. That's another problem. What about flexible tanks? Sources?
I can cut between both hatches as you had to do, but the other problem I have is that the tank extends beyond the hatches in all four directions. I think I can cut it up with a sawzall and then compress it down before removing. I'm also wondering if your tank was glassed in place. I think mine is. That's another problem. What about flexible tanks? Sources?
Use a flexible tank........
David: If you install a flexible tank you will be doing it again in a few years. When you sail these thing rub back and forth. It wears out the tanks from small abrasions. In time it will be leaking again. There was a recent post where someone had done this and it leaked from the beginning. If you are going to purchase quality bladder they are more expensive that a good poly tank. Do yourself a favor. Spend a little more doing the job correctly now and you'll have more time to sail later.
David: If you install a flexible tank you will be doing it again in a few years. When you sail these thing rub back and forth. It wears out the tanks from small abrasions. In time it will be leaking again. There was a recent post where someone had done this and it leaked from the beginning. If you are going to purchase quality bladder they are more expensive that a good poly tank. Do yourself a favor. Spend a little more doing the job correctly now and you'll have more time to sail later.
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David Popken
Not even a question in my opinion.
David: I do not think that there is even a question regarding the best tanks. I would not even consider any metal tanks on the boat. Alum. & Stainless have their own set of problems. The poly tanks are not expensive. You could actually fill it with clorine or bleach and the tank would still last for many years. There is no question about the problems you would encounter with metal tanks. Just ask some of the owners with metal fuel and holding tanks (water is not as much of a problem). They are light weight and not very expensive either. You just want to make sure that they are properly mounted and secured.
David: I do not think that there is even a question regarding the best tanks. I would not even consider any metal tanks on the boat. Alum. & Stainless have their own set of problems. The poly tanks are not expensive. You could actually fill it with clorine or bleach and the tank would still last for many years. There is no question about the problems you would encounter with metal tanks. Just ask some of the owners with metal fuel and holding tanks (water is not as much of a problem). They are light weight and not very expensive either. You just want to make sure that they are properly mounted and secured.
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Leighton
Some things grow old then replace it...
I have a 1977 Cat27, Hull #3621 and I'm replacing my water tank with a brand new 13 gal. Poly tank by Todd. The tank is larger than the opening but the previous owner cut the fiberglass support between the two openings in the starboard sette but has been reinforced with a piece of wood that bridges the entire depth of the sette. I would replace that aluminum tank just from the taste of the water.
I have a 1977 Cat27, Hull #3621 and I'm replacing my water tank with a brand new 13 gal. Poly tank by Todd. The tank is larger than the opening but the previous owner cut the fiberglass support between the two openings in the starboard sette but has been reinforced with a piece of wood that bridges the entire depth of the sette. I would replace that aluminum tank just from the taste of the water.
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