I've been reading about this "weak spot" in the H37c for years, and it happened this morning. We live aboard on a mooring, so it's time to get out the bucket. I intend to scour the archives, but if anyone has a current lead on a replacement (rigid, not a bladder) tank, I would sure appreciate it. Thanks.
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"Weak spot?"
If your boat had a metal holding tank, that could be considered a "weak spot," but metal tanks don't just suddenly burst...they start to "weep" at a seam or a fitting first, then turn into a colander. Not many people could ignore the odor from all those leaks long enough for the whole bottom to fall out, though. So what's your tank made of, and exactly DID happen? If your tank was metal, you don't want to replace it with another metal one. You'd only be replacing an old "weak spot" with a new one. Ronco Plastics http://ronco-plastics.com is your best source for a new tank. They make top quality plastic tanks for a very reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular...and the install fittings in the sizes and locations specified by the customer when they make the tank. Their drawings can be oriented any direction, 'cuz there's no top or bottom till the fittings go in, and you determine where they go...so rotate 'em, flip 'em end for end and then rotate 'em. There's no rule that says the new tank has to go into the same space as the old one...so if there's another place within 6' of the toilet where a larger tank will fit, now's the time to move it.
If your boat had a metal holding tank, that could be considered a "weak spot," but metal tanks don't just suddenly burst...they start to "weep" at a seam or a fitting first, then turn into a colander. Not many people could ignore the odor from all those leaks long enough for the whole bottom to fall out, though. So what's your tank made of, and exactly DID happen? If your tank was metal, you don't want to replace it with another metal one. You'd only be replacing an old "weak spot" with a new one. Ronco Plastics http://ronco-plastics.com is your best source for a new tank. They make top quality plastic tanks for a very reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular...and the install fittings in the sizes and locations specified by the customer when they make the tank. Their drawings can be oriented any direction, 'cuz there's no top or bottom till the fittings go in, and you determine where they go...so rotate 'em, flip 'em end for end and then rotate 'em. There's no rule that says the new tank has to go into the same space as the old one...so if there's another place within 6' of the toilet where a larger tank will fit, now's the time to move it.
Thanks
Jeez, Alan, I guess I "ignored" it for 20 years of constant use and it gave us 20 years of excellent service....that's why. Peggy, I hoped you'd check in on this one. Actually, there was no leakage, odor or other warning. I haven't opened it up yet, but I suspect a seam is probably the culprit. I heard a soft "pop" before the odor announced the problem. I will follow your good advice and mount a Ronco (couldn't remember the name) tank in the locker just forward of the current location. Thanks.
Jeez, Alan, I guess I "ignored" it for 20 years of constant use and it gave us 20 years of excellent service....that's why. Peggy, I hoped you'd check in on this one. Actually, there was no leakage, odor or other warning. I haven't opened it up yet, but I suspect a seam is probably the culprit. I heard a soft "pop" before the odor announced the problem. I will follow your good advice and mount a Ronco (couldn't remember the name) tank in the locker just forward of the current location. Thanks.
Vent Line Blocked
If it popped maybe the vent line was blocked. It takes very little pressure (pounds per square inch) to create large forces (many square inches) in a tank, wether it be holding, diesel or water. If the tank was already weakened that would bring the sudden failure. Ensuring these vents are clear is important as the flexing caused by cycling pressure can shorten the life of tanks. You can also get other issues like diesel being burped out of the vent. I have gone to some trouble to make sure that the vent lines run uniformly "upwards", so there are no places for liquid to accumulate. One more thing to be careful of is when pumping out a holding tank there is an adequate path for air to get in. The 3/4 inch vents are most likley too small to be relied on. European standards, I am told, require the vent to be the same size as the pump out. John Brecher
If it popped maybe the vent line was blocked. It takes very little pressure (pounds per square inch) to create large forces (many square inches) in a tank, wether it be holding, diesel or water. If the tank was already weakened that would bring the sudden failure. Ensuring these vents are clear is important as the flexing caused by cycling pressure can shorten the life of tanks. You can also get other issues like diesel being burped out of the vent. I have gone to some trouble to make sure that the vent lines run uniformly "upwards", so there are no places for liquid to accumulate. One more thing to be careful of is when pumping out a holding tank there is an adequate path for air to get in. The 3/4 inch vents are most likley too small to be relied on. European standards, I am told, require the vent to be the same size as the pump out. John Brecher
Avalon, Have fun ripping it out
and what he meant by a "weak spot" is these boats are all over 20 years old and all had metal tanks and all have or will fail in the next few years ( days). the only good thing about the tank was the location- it is a foot away from the head, so short hose run.
and what he meant by a "weak spot" is these boats are all over 20 years old and all had metal tanks and all have or will fail in the next few years ( days). the only good thing about the tank was the location- it is a foot away from the head, so short hose run.
Ronco a good bet
I agree with Peggy about Ronco, and you'll find details on which tank will fit where in the archives. I like the idea of using the space under the V-berth where I currently have a bladder (ugh), as it is close enough to the head, and existing plumbing, to require less rework... Have fun. Sanders s/v Good News
I agree with Peggy about Ronco, and you'll find details on which tank will fit where in the archives. I like the idea of using the space under the V-berth where I currently have a bladder (ugh), as it is close enough to the head, and existing plumbing, to require less rework... Have fun. Sanders s/v Good News
I'd bet real money that the vent was/is blocked
'Cuz that's the only thing that can cause a sudden catastrophic failure. And not only in "weak" aluminum tanks, but even brand new thick-walled plastic or stainless steel tanks. In fact, that happened to a poster here a few years ago during his first shakedown cruise after completing restoration of an older boat. He kept pumping a toilet that was becoming harder and harder to pump till his brand new stainless tank finally burst at a seam. So while the aluminum tanks on older boats may be a "weak spot" in the boats, this time it was the owner who was the "weak spot." Didn't you notice that the toilet was getting a bit harder to pump as the tank became increasingly pressurized??? Or maybe your tank had deteriorated enough that it let go before it became that noticeable. But you still deserve a rap on the knuckles for ignoring your tank vent. I'm even more amazed you managed to get away with that for 20 years than I am that your aluminum tank lasted that long. As John said, it's essential that the tank vent line be kept clear...'cuz if air in the tank displaced by incoming waste can't out, the tank becomes pressurized...if air can't get in to replace contents as they're pumped out, a strong pumpout can implode even the sturdiest tank. The two most common places for vent blockages to occur are the vent thru-hull and the connection to the tank--both the fitting and that end of the vent line. If you want to prevent it, backflush the vent with a hose every time you pump out and/or wash the boat. If your vent thru-hull isn't designed to let you do that, replace it with one that is.
'Cuz that's the only thing that can cause a sudden catastrophic failure. And not only in "weak" aluminum tanks, but even brand new thick-walled plastic or stainless steel tanks. In fact, that happened to a poster here a few years ago during his first shakedown cruise after completing restoration of an older boat. He kept pumping a toilet that was becoming harder and harder to pump till his brand new stainless tank finally burst at a seam. So while the aluminum tanks on older boats may be a "weak spot" in the boats, this time it was the owner who was the "weak spot." Didn't you notice that the toilet was getting a bit harder to pump as the tank became increasingly pressurized??? Or maybe your tank had deteriorated enough that it let go before it became that noticeable. But you still deserve a rap on the knuckles for ignoring your tank vent. I'm even more amazed you managed to get away with that for 20 years than I am that your aluminum tank lasted that long. As John said, it's essential that the tank vent line be kept clear...'cuz if air in the tank displaced by incoming waste can't out, the tank becomes pressurized...if air can't get in to replace contents as they're pumped out, a strong pumpout can implode even the sturdiest tank. The two most common places for vent blockages to occur are the vent thru-hull and the connection to the tank--both the fitting and that end of the vent line. If you want to prevent it, backflush the vent with a hose every time you pump out and/or wash the boat. If your vent thru-hull isn't designed to let you do that, replace it with one that is.
Info request on custom tank
Jim W. can you supply some details on how you fit a 25 gal tank in a 15 gal space? I need to replace my tank as well and have been thinking a lot about how to replace the tank in place. Any pictures you can post would be great. How did you install the tank? Did you cut into the shower seat or go in through the v-berth? Thanks for any more information you can supply.
Jim W. can you supply some details on how you fit a 25 gal tank in a 15 gal space? I need to replace my tank as well and have been thinking a lot about how to replace the tank in place. Any pictures you can post would be great. How did you install the tank? Did you cut into the shower seat or go in through the v-berth? Thanks for any more information you can supply.
$750 for a custom holding tank??? Yikes!!!
that's nearly twice what a good quality welded plstic tank should cost. We need to talk...'cuz I guarantee you that we can find a good location--maybe with a little modification--for a new "stock" tank from Ronco that's at least 25 gal. If you'd like to take me up on that offer, email me...I'm in all the owner directories.
that's nearly twice what a good quality welded plstic tank should cost. We need to talk...'cuz I guarantee you that we can find a good location--maybe with a little modification--for a new "stock" tank from Ronco that's at least 25 gal. If you'd like to take me up on that offer, email me...I'm in all the owner directories.
Peggie's advice about vents
I'm glad Peggie checked in with what has to seem to her like a broken-record-like mantra of 'vent line, vent line, vent line!' I've been moonlighting at West Marine and have repeated it to everyone. The vent line just has to be big enough to to allow real air (oxygen) into the tank. Peggie advises a vertical vent, or, if it must go out a side wall of the tank, two, one to either side. The hose should be 3/4" minimum, 1" preferred. There should be no check valves, kinks, or tight turns in the hose line. The good thing about that is a sailboat usually spends its time with wind on the side, so that with a vent to either side you might just get flow-through ventilation-- the best thing you could have. This is not a subject most people like chatting about, and I'll bet the vast majority of people choose to live in denial about it. But facts don't lie, and denial usually comes up and spanks us. I replaced my stupid little 5/8" gas-tank vents with their unnecessary flame-arrestor screens, that I chose just because they looked cute (just like the overwhelming majority of production boats use-- with their airless stinky holding tanks and myriad of chemicals from a whole 'nother industry just to stop the stink). I found a terrific all-stainless Attwood through-hull in 3/4" hose size and am installing one on each side to provide cross-ventilation for the (plastic) holding tank under the vee berth in my H-25. Ronco tanks are good quality and their service from California is excellent. I've bought them for C-44 production.
I'm glad Peggie checked in with what has to seem to her like a broken-record-like mantra of 'vent line, vent line, vent line!' I've been moonlighting at West Marine and have repeated it to everyone. The vent line just has to be big enough to to allow real air (oxygen) into the tank. Peggie advises a vertical vent, or, if it must go out a side wall of the tank, two, one to either side. The hose should be 3/4" minimum, 1" preferred. There should be no check valves, kinks, or tight turns in the hose line. The good thing about that is a sailboat usually spends its time with wind on the side, so that with a vent to either side you might just get flow-through ventilation-- the best thing you could have. This is not a subject most people like chatting about, and I'll bet the vast majority of people choose to live in denial about it. But facts don't lie, and denial usually comes up and spanks us. I replaced my stupid little 5/8" gas-tank vents with their unnecessary flame-arrestor screens, that I chose just because they looked cute (just like the overwhelming majority of production boats use-- with their airless stinky holding tanks and myriad of chemicals from a whole 'nother industry just to stop the stink). I found a terrific all-stainless Attwood through-hull in 3/4" hose size and am installing one on each side to provide cross-ventilation for the (plastic) holding tank under the vee berth in my H-25. Ronco tanks are good quality and their service from California is excellent. I've bought them for C-44 production.
Ronco Tank - Odor
Granted that Ronco tanks are the best and easiest to control, how permeable are they; that is, how well do they contain odor.
Granted that Ronco tanks are the best and easiest to control, how permeable are they; that is, how well do they contain odor.
Ronco tanks don't permeate
In 20 years, I've yet to hear of a Ronco tank permeating. I have occasionally run into someone who thought one had permeated, but it turned out to be fitting or hoses in the same compartment. The walls of their smallest tanks are about 3/8"--at least 50% thicker than most--and increase in thickness as needed to support the weight of the contents in larger tanks. Fwiw, Ronco supplies tanks most of the high builders and quite few production builders too...in fact, they've made Catalina's water and waste tanks for as long as I can remember.
In 20 years, I've yet to hear of a Ronco tank permeating. I have occasionally run into someone who thought one had permeated, but it turned out to be fitting or hoses in the same compartment. The walls of their smallest tanks are about 3/8"--at least 50% thicker than most--and increase in thickness as needed to support the weight of the contents in larger tanks. Fwiw, Ronco supplies tanks most of the high builders and quite few production builders too...in fact, they've made Catalina's water and waste tanks for as long as I can remember.
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