My odd shaped, expensive to duplicate, aluminium holding tank has developed a pinhole leak. Am giving some thought to cutting out top, leaving a 1.5 inch lip, and lining the entire tank with epoxy resin and glass fiber. Would also add new fittings and build new top piece. Do you have any thoughts, and or suggestions for this project?
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Replace it with a plastic tank
The first leak in an aluminum tank is ONLY the first leak.The average lifespan of a metal waste tank is only about 10 years...typically it eats through a weld at a seam or fitting in 2-5 years, turns the tank into a collander within about 10 years...so attempting to repair it by lining it with epoxy or other coating would only be a temporary "band aid" over a lot of rust and pinholes about to break through. A good quality plastic tank, otoh, will last as long as your hull. Your best source fo a new tank is Ronco Plastics (http://www.ronco-plastics.com) They make top quality tanks for a very reasonable price and have more than 400 shapes and sizes, including over 100 that are non-rectangular. And they install fittings in the sizes/locations specified by the customer when they make the tank. If the current tank location is more than about 6' from the toilet, I also recommend that you find another location for a tank that is within about 6' of the toilet.
The first leak in an aluminum tank is ONLY the first leak.The average lifespan of a metal waste tank is only about 10 years...typically it eats through a weld at a seam or fitting in 2-5 years, turns the tank into a collander within about 10 years...so attempting to repair it by lining it with epoxy or other coating would only be a temporary "band aid" over a lot of rust and pinholes about to break through. A good quality plastic tank, otoh, will last as long as your hull. Your best source fo a new tank is Ronco Plastics (http://www.ronco-plastics.com) They make top quality tanks for a very reasonable price and have more than 400 shapes and sizes, including over 100 that are non-rectangular. And they install fittings in the sizes/locations specified by the customer when they make the tank. If the current tank location is more than about 6' from the toilet, I also recommend that you find another location for a tank that is within about 6' of the toilet.
Plastic Tanks are great
I don't know what model boat that you have, but plastic tanks are great. They don't leak and you can calibrate your tank level gauge by shining a flashlight on the side of the plastic tank. And in most cases you can increase the size of your holding tank when replacing it. Metal holding tanks should be against the law.
I don't know what model boat that you have, but plastic tanks are great. They don't leak and you can calibrate your tank level gauge by shining a flashlight on the side of the plastic tank. And in most cases you can increase the size of your holding tank when replacing it. Metal holding tanks should be against the law.
aluminum tank repair
The repairs could be made with epoxy and glass as you have described, but I think if it were me, I would first look into the plastic replacement tank option first. The cost and time involved in repairing the tank could easily be more than a new tank. That said, the corrosion of aluminum tanks often starts around the mounting straps where disilmilar metals in the presence of moisture create a galvanic reaction - it makes a battery - and the tank is the metal that is reduced. Be sure, if you make this repair, to clean all contaminates, abrade, and etch the aluminum surfaces with our 860 aluminum etch kit. Also, be sure to coat and glass the outside of the tank where the straps are to remove the metal to metal contact.
The repairs could be made with epoxy and glass as you have described, but I think if it were me, I would first look into the plastic replacement tank option first. The cost and time involved in repairing the tank could easily be more than a new tank. That said, the corrosion of aluminum tanks often starts around the mounting straps where disilmilar metals in the presence of moisture create a galvanic reaction - it makes a battery - and the tank is the metal that is reduced. Be sure, if you make this repair, to clean all contaminates, abrade, and etch the aluminum surfaces with our 860 aluminum etch kit. Also, be sure to coat and glass the outside of the tank where the straps are to remove the metal to metal contact.
Can holding tanks be made of epoxy?
Is there a smell or other reason a holding tank cant be made of epoxy and fiberglass? couldnt a barrier coat be used on the inside surface ?
Is there a smell or other reason a holding tank cant be made of epoxy and fiberglass? couldnt a barrier coat be used on the inside surface ?
Holding tanks can be made of anything...
It's only a matter of "why would anyone with any sense do it?" when it comes to some materials. If it were a new tank, it might make sense to coat the inside of it with expoxy...although that hasn't proven to extend the typical 10 yr life expectancy of a metal tank by any noticeable time. Fiberglass/epoxy tanks haven't been shown to be bulletproof either...any hairline crack will allow moisture into the fiberglass to cause blistering a rot--something that goes unnoticed till it's severe because it's happening inside the tank. They're also very heavy compared to polyethelene. IMO, any DIY tank will not be as durable as a good quality poly tank...and will cost you more in time and effort than it's worth. Ronco Plastics shows more than 400 shapes and sizes...if you can't find one that'll fit in at least one workable space on your boat, you're not trying.
It's only a matter of "why would anyone with any sense do it?" when it comes to some materials. If it were a new tank, it might make sense to coat the inside of it with expoxy...although that hasn't proven to extend the typical 10 yr life expectancy of a metal tank by any noticeable time. Fiberglass/epoxy tanks haven't been shown to be bulletproof either...any hairline crack will allow moisture into the fiberglass to cause blistering a rot--something that goes unnoticed till it's severe because it's happening inside the tank. They're also very heavy compared to polyethelene. IMO, any DIY tank will not be as durable as a good quality poly tank...and will cost you more in time and effort than it's worth. Ronco Plastics shows more than 400 shapes and sizes...if you can't find one that'll fit in at least one workable space on your boat, you're not trying.
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