I recently purchased a pre-owned 1999 Hunter 310. I am a new Hunter owner, and am new to larger sailboats. Last weekend, I tried to pump out the holding tank for the first time. When I unscrewed the cap to the pump-out, I got a large geyser of... well, really icky stuff. The holding tank was clearly pressurized, and I'm pretty sure it's not supposed to work that way. I'm guessing that we waited too long to pump out, and that the plastic tank had distended to accomidate our last few uses. It was clearly somewhat distended when I inspected it; after I pumped out, it re-formed back to its square shape. I'm lucky I finally pumped out when I did, or I'd have had a really horrible mess when the tank ruptured. My question is this: isn't there a vent to the holding tank, and is it possible that my vent is clogged? If so, then how should I go about unclogging it? It doesn't seem right that the tank should become pressurized like that without some sort of warning or venting. L. Baker, "Flat Broke" out of Grapevine, TX
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Yes, the tank is vented, and yes...
It's obviously clogged. It has nothing to do with how long waste is in the tank, only with whether air displaced by waste coming into can get out and waste sucked out by a pump out or macerator pump can be replaced by air. It's doubtful (but not impossible) that pressuring the tank would have exploded it...the more likely scenario is a toilet bowl eruption 'cuz back up the hose is the line of least resistance. You're lucky suction from the pumpout didn't implode the tank...and it's highly likely that the pumpout couldn't empty the tank...that the pumpout only got a few gallons out before it pulled a vacuum. You're the second person in a week to have the same problem, so instead of repeating myself here, I'll ask you to go to the Head Mistress forum and read the holding tank vent threads there. While you're there, I suggest you also read the articles in the Reference Library on the right hand side of the forum home page. It wouldn't hurt to ramble through a whole bunch of the head and plumbing discussions, in both the active Head Mistress files and the archives. And finally, I suggest you read the article in the link I've provided. Between it and the articles in the Library you'll find the answers to more questions than it ever occurs to most boat owners to ask. Then I want you to go back to your boat and trace all the hoses attached to the head and the holding tank, to see where they lead. When you find the vent hose coming off the top of the tank, go to the outside of the boat and inspect the thru-hull it's attached to. I suspect you'll find it clogged with anything from dust dirt and pollen to a dirt dauber nest. Clean it out...water under pressure may do it...and if there's a screen in it, remove it...'cuz it's just gonna get clogged up again. Welcome to the fun part of boat ownership.
It's obviously clogged. It has nothing to do with how long waste is in the tank, only with whether air displaced by waste coming into can get out and waste sucked out by a pump out or macerator pump can be replaced by air. It's doubtful (but not impossible) that pressuring the tank would have exploded it...the more likely scenario is a toilet bowl eruption 'cuz back up the hose is the line of least resistance. You're lucky suction from the pumpout didn't implode the tank...and it's highly likely that the pumpout couldn't empty the tank...that the pumpout only got a few gallons out before it pulled a vacuum. You're the second person in a week to have the same problem, so instead of repeating myself here, I'll ask you to go to the Head Mistress forum and read the holding tank vent threads there. While you're there, I suggest you also read the articles in the Reference Library on the right hand side of the forum home page. It wouldn't hurt to ramble through a whole bunch of the head and plumbing discussions, in both the active Head Mistress files and the archives. And finally, I suggest you read the article in the link I've provided. Between it and the articles in the Library you'll find the answers to more questions than it ever occurs to most boat owners to ask. Then I want you to go back to your boat and trace all the hoses attached to the head and the holding tank, to see where they lead. When you find the vent hose coming off the top of the tank, go to the outside of the boat and inspect the thru-hull it's attached to. I suspect you'll find it clogged with anything from dust dirt and pollen to a dirt dauber nest. Clean it out...water under pressure may do it...and if there's a screen in it, remove it...'cuz it's just gonna get clogged up again. Welcome to the fun part of boat ownership.
Always flush out the vent line!
Be sure to flush out your vent line EVERY time you pump the head. If you overfill the tank you can plug up the vent. Then there are the critters that nest in the vent. Also a good idea not to let the tank get too full if you have control.
Be sure to flush out your vent line EVERY time you pump the head. If you overfill the tank you can plug up the vent. Then there are the critters that nest in the vent. Also a good idea not to let the tank get too full if you have control.
Thanks, but how can I...
Thanks, Peggy. I've already traced the line; I'll try running water back through it with a garden hose fitting and visually verify the flow back into the tank. Unless you can suggest a better means.... Which brings me to my next question. How can I be sure that I've sufficiently purged the line of its obstruction(s), rather than just poked a hole through them? The obvious suggestion that comes to mind is to detach the vent hose from the tank, couple it to a garden hose, and blast it clean from inside, though I guess this could get a bit messy. Any thoughts? The hose disappears into the wall in the head; finding its attachment point to the through-hull fitting escapes me at the moment, though I'm sure I can figure it out. Thanks for your response, and the pointers to the Head mistress articles. They helped a lot. I'll master this thing yet - I hope before I do something that creates a real mess! Best regards, Larry Baker
Thanks, Peggy. I've already traced the line; I'll try running water back through it with a garden hose fitting and visually verify the flow back into the tank. Unless you can suggest a better means.... Which brings me to my next question. How can I be sure that I've sufficiently purged the line of its obstruction(s), rather than just poked a hole through them? The obvious suggestion that comes to mind is to detach the vent hose from the tank, couple it to a garden hose, and blast it clean from inside, though I guess this could get a bit messy. Any thoughts? The hose disappears into the wall in the head; finding its attachment point to the through-hull fitting escapes me at the moment, though I'm sure I can figure it out. Thanks for your response, and the pointers to the Head mistress articles. They helped a lot. I'll master this thing yet - I hope before I do something that creates a real mess! Best regards, Larry Baker
Blast water at the thru-hull
Don't just try to run water through it. An air horn sometimes works too...just hold it over the thru-hull and honk it. Best way to find out if you've completely cleared it is to fill your tank with water till it's overflowing out the vent. You can stick a hose (but NOT the same one you use to fill your potable water tank!) in the pumpout fitting. If it's a good strong stream, the line is open. And btw, let the water run till it's clear to rinse out your tank. If you've already identified the correct thru-hull, it's not critical that you trace the entire path of the vent hose. It's just a good idea to know which hose is attached to what at both ends and know where the hoses go... A crisis is no time to START hunting for thru-hulls, seacocks etc.
Don't just try to run water through it. An air horn sometimes works too...just hold it over the thru-hull and honk it. Best way to find out if you've completely cleared it is to fill your tank with water till it's overflowing out the vent. You can stick a hose (but NOT the same one you use to fill your potable water tank!) in the pumpout fitting. If it's a good strong stream, the line is open. And btw, let the water run till it's clear to rinse out your tank. If you've already identified the correct thru-hull, it's not critical that you trace the entire path of the vent hose. It's just a good idea to know which hose is attached to what at both ends and know where the hoses go... A crisis is no time to START hunting for thru-hulls, seacocks etc.
Thanks again, Peggy
Thanks again; your advice really helps. I found the through-hull fitting and it was quite clearly fouled with "stuff." I cleared the stuff as best I could, and blasted it with a "water blaster" fitting on a garden hose; I don't have much confidence that it really cleared out all the obstructions, but the tank is clearly venting (no back pressure after many flushes). Or more accurately, it's venting enough to prevent back-pressure build-up. Next time I pump out, after I clear the tank, I'll try your suggestion of attaching a regular hose (theirs, not mine to the fitting and causing a good strong flow through the through-hull until it's clear. That seems to be about the only easy way to do it. My only concern at this point is the fear that I comprimised the integrigy of the tubing or the tank. I'm watching closely for leaks, but at this point I don't see any. Ah, the aromatic joys of boat ownership! Thanks again, Larry
Thanks again; your advice really helps. I found the through-hull fitting and it was quite clearly fouled with "stuff." I cleared the stuff as best I could, and blasted it with a "water blaster" fitting on a garden hose; I don't have much confidence that it really cleared out all the obstructions, but the tank is clearly venting (no back pressure after many flushes). Or more accurately, it's venting enough to prevent back-pressure build-up. Next time I pump out, after I clear the tank, I'll try your suggestion of attaching a regular hose (theirs, not mine
to the fitting and causing a good strong flow through the through-hull until it's clear. That seems to be about the only easy way to do it. My only concern at this point is the fear that I comprimised the integrigy of the tubing or the tank. I'm watching closely for leaks, but at this point I don't see any. Ah, the aromatic joys of boat ownership! Thanks again, LarryI doubt if you damaged anything
It's almost impossible to damage a hose, and your tank returned to its original shape, so it's prob'ly ok. And, since 99% of vent clogs happen in the thru-hull and your tank is now venting, there's a good chance that you've cleared it completely. But keep an eye on things, and flush the system out very thoroughly next time you pump out. Btw...you won't attach a hose to any fitting...you'll just stick the end of it--sans sprayer--in the pumpout fitting.
It's almost impossible to damage a hose, and your tank returned to its original shape, so it's prob'ly ok. And, since 99% of vent clogs happen in the thru-hull and your tank is now venting, there's a good chance that you've cleared it completely. But keep an eye on things, and flush the system out very thoroughly next time you pump out. Btw...you won't attach a hose to any fitting...you'll just stick the end of it--sans sprayer--in the pumpout fitting.
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