What is the expected life of an aluminium holding tank and what caused the failures. Is there anything that can be done to extend the life, treatments, fresh water, Etc? I am going on 11 years and am not looking forward to the replacement.
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Steve Carpman
Aluminum Tank
Our 1991 Legend 37.5 still has its original aluminum holding tank. A pressure test earlier this year disclosed a small leak at the fittings on the top of the tank - not serious. Since its normally the welds that fail (the chemical content of urine apparently eats the welds), I have not been able to figure out why the tank is leaking on its top. We are changing the tank out next spring , as sooner or later it will leak. We have owned the boat for two years, but the PO always washed the tank throughly with fresh water as it was pumped out. We continue to do the same. We try not to leave any waste in the tank when we leave the boat, but that is not always possible. I beleive we have been lucky thus far with our tank. No point in pushing it any further.
Our 1991 Legend 37.5 still has its original aluminum holding tank. A pressure test earlier this year disclosed a small leak at the fittings on the top of the tank - not serious. Since its normally the welds that fail (the chemical content of urine apparently eats the welds), I have not been able to figure out why the tank is leaking on its top. We are changing the tank out next spring , as sooner or later it will leak. We have owned the boat for two years, but the PO always washed the tank throughly with fresh water as it was pumped out. We continue to do the same. We try not to leave any waste in the tank when we leave the boat, but that is not always possible. I beleive we have been lucky thus far with our tank. No point in pushing it any further.
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Terry
The expected life of any tank is until they start.
to leak. If the tank is flushed out with fresh water after eash cruise they should last many years. It is when sewage is left in the tank for long periods that becomes the culprit. After each cruise we always close the raw water intake/s then: 1. Pump the tank out, then fill with fresh water, 2. Pump it out again, then flush one gallon of fresh water down each head to clear out the hoses. 3. Apply city water to the vent scupper to clear out the vent line. 4. Fill the tank with about three gallons of fresh water, pump out again. 5. Repeat until the pumped out water is clear. 6. Flush qone quart of Odorlos/fresh water mix down each head. Our head system has been trouble free ever since we applied the above procedure recommended by Peggie Hall. As long as your tank is not leaking I would use it until it does, then go with a hard plastic replacement. Terry
to leak. If the tank is flushed out with fresh water after eash cruise they should last many years. It is when sewage is left in the tank for long periods that becomes the culprit. After each cruise we always close the raw water intake/s then: 1. Pump the tank out, then fill with fresh water, 2. Pump it out again, then flush one gallon of fresh water down each head to clear out the hoses. 3. Apply city water to the vent scupper to clear out the vent line. 4. Fill the tank with about three gallons of fresh water, pump out again. 5. Repeat until the pumped out water is clear. 6. Flush qone quart of Odorlos/fresh water mix down each head. Our head system has been trouble free ever since we applied the above procedure recommended by Peggie Hall. As long as your tank is not leaking I would use it until it does, then go with a hard plastic replacement. Terry
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Peggie Hall/HeadMistress
10 years is typical.
Any longer is living on borrowed time. Most uncoated aluminum tanks typically start to leak at a weld at seam or fitting within 2-5 years...and turn into a collander within about 10 years. The culprit: urine. (Read my reply in another thread at http://www.sailboatowners.com/forums/rview.tpl?rid=2003309134035.54&forumabr=thm&fno=11) Religiously rinsing it out VERY thoroughly so that no waste sits in it can extend the life by a year or two, but after about 10 years, the tank is living on borrowed time. The time to replace is when you discover the first leak...'cuz the first leak is only the FIRST leak to break through...more aren't far behind. But until you see the first leak, pressure test it annually each spring and keep on keepin' on with it.
Any longer is living on borrowed time. Most uncoated aluminum tanks typically start to leak at a weld at seam or fitting within 2-5 years...and turn into a collander within about 10 years. The culprit: urine. (Read my reply in another thread at http://www.sailboatowners.com/forums/rview.tpl?rid=2003309134035.54&forumabr=thm&fno=11) Religiously rinsing it out VERY thoroughly so that no waste sits in it can extend the life by a year or two, but after about 10 years, the tank is living on borrowed time. The time to replace is when you discover the first leak...'cuz the first leak is only the FIRST leak to break through...more aren't far behind. But until you see the first leak, pressure test it annually each spring and keep on keepin' on with it.
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Jim Rushing
Eight Years
Don, mine lasted 8 years in a fresh water lake. But when it starts to leak, it is so slow that it takes time before you realize it. On a 35.5, the water appears at the sump in front of the shaft seal. I have a dry seal so I knew that it wasn't coming from there. If you have the normal shaft seal, you wont identify the problem until it is major issue. And it really wasn't to smelly until I opened the bulkhead hatch to access the tank.
Don, mine lasted 8 years in a fresh water lake. But when it starts to leak, it is so slow that it takes time before you realize it. On a 35.5, the water appears at the sump in front of the shaft seal. I have a dry seal so I knew that it wasn't coming from there. If you have the normal shaft seal, you wont identify the problem until it is major issue. And it really wasn't to smelly until I opened the bulkhead hatch to access the tank.
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Shaun Moore
9 years in my 33.5
I just replaced mine, it lasted 9 years. I went back with another aluminum tank that was coated on the inside. I called the company , Ezell Industries, in Florida who had made the original tank and they still had the Hunter drawings. They made me one that dropped in perfectly. Polyethylene is the way to go if you want it to last forever, but for ease of replacement an aluminum tank with an epoxy coating that drops right in was pretty simple. On the 33.5 all the hoses come out of the top of the tank and is not hard to get to as it's under the u shaped couch around the table. I did not want to re-engineer the set up with a PE tank that had some fittings at the bottom, etc. When you change out your tank plan on changing the discharge hose from the toilet to the tank, mine had a much smaller I D due to all the caked salt/sediment, ie, urine and salt water crystallized.
I just replaced mine, it lasted 9 years. I went back with another aluminum tank that was coated on the inside. I called the company , Ezell Industries, in Florida who had made the original tank and they still had the Hunter drawings. They made me one that dropped in perfectly. Polyethylene is the way to go if you want it to last forever, but for ease of replacement an aluminum tank with an epoxy coating that drops right in was pretty simple. On the 33.5 all the hoses come out of the top of the tank and is not hard to get to as it's under the u shaped couch around the table. I did not want to re-engineer the set up with a PE tank that had some fittings at the bottom, etc. When you change out your tank plan on changing the discharge hose from the toilet to the tank, mine had a much smaller I D due to all the caked salt/sediment, ie, urine and salt water crystallized.
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Brian Leney
8 years
We got a disappointing 8 years (seasons) out of ours. I was disappointed because, knowing of the "problem," I did all that I could to maintain that tank: pumped-out immediately after each cruise (usually just a weekend), and then followed with a fresh-water flush. And it was only my wife and I using it most of the time. I had a pin-hole leak at the bottom of a side. Tell-tale signs are tiny piles of corroded aluminum on the tank or on the floor beside it. Akin to the little piles of sawdust that carpenter bees make. That's just before the tank leaks liquid all the way. Do not go beyond 10 years is my advice. The project is inevitable assuming you will be keeping the boat. Do the project at your leisure instead of being rushed after the gush!
We got a disappointing 8 years (seasons) out of ours. I was disappointed because, knowing of the "problem," I did all that I could to maintain that tank: pumped-out immediately after each cruise (usually just a weekend), and then followed with a fresh-water flush. And it was only my wife and I using it most of the time. I had a pin-hole leak at the bottom of a side. Tell-tale signs are tiny piles of corroded aluminum on the tank or on the floor beside it. Akin to the little piles of sawdust that carpenter bees make. That's just before the tank leaks liquid all the way. Do not go beyond 10 years is my advice. The project is inevitable assuming you will be keeping the boat. Do the project at your leisure instead of being rushed after the gush!
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