Hi, After a cruise up in Maine, where pumpouts were scarce (and one overflowing incident, yuck!), I want to figure out a better solution to pumpouts than I have now. Going through Whale's brochure, they reccomend a pretty complicated system: put a Y valve on the pumpout house, then a pump, then a vented loop (ugh, another hole in the deck), and then your throughhull. With this setup, you can pump out your holding tank while underway (presumably 3 miles out, as required by law). My question is this: all that permanently installed stuff is great, but why not just put a nice waste hand pump on a hose that fits onto your normal pumpout fitting? Then you can just pump out your head on deck, and then I suppose rinse the hose through with sea water. Has anyone done this? Does anyone have advice on it? Will I just NEVER rinse that hose as well as I'd like to?
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I haven't done it
But on our RV, we drain out tanks occasioanlyl into the sewage vent in our front yard, rather then drive to a holding station. We then close the drain, dump a few gallons of water down the toilet, do a bunch of fwd- stop- reverese-stop to shake things up a bit, then drain that. the drainage hose is rinsed with fresh water and stored in a pipe underneath. I'd think you could then drop the inlet and outlet both into the water and pump to your hearts content to flush everything out..but i wouldn't want the pump stored beneath my bed!
But on our RV, we drain out tanks occasioanlyl into the sewage vent in our front yard, rather then drive to a holding station. We then close the drain, dump a few gallons of water down the toilet, do a bunch of fwd- stop- reverese-stop to shake things up a bit, then drain that. the drainage hose is rinsed with fresh water and stored in a pipe underneath. I'd think you could then drop the inlet and outlet both into the water and pump to your hearts content to flush everything out..but i wouldn't want the pump stored beneath my bed!
impractical
The RV is presumably above water level as compared with a boat holding tank which is not. There are two obstacles which would make this difficult if not impossible on a boat- 1. to inset a hose "that fits onto your normal pumpout fitting" would require an air tight seal if you hope to draw the requisite vacuum (requiring an expensive pump). The alternative being to drop a hose all the way to the bottom of the tank might be impractical. 2. any reasonably sized pump would necessarily have to be close to the level of the tank to prime itself and also would have to pump the head ( increased vertical level) to reach overboard ( a messy visual image). Assuming someone has figured out a practical solution to this, you could give it a try but it seems futile to me and also it seems like a pretty messy alternative to doing it correctly.
The RV is presumably above water level as compared with a boat holding tank which is not. There are two obstacles which would make this difficult if not impossible on a boat- 1. to inset a hose "that fits onto your normal pumpout fitting" would require an air tight seal if you hope to draw the requisite vacuum (requiring an expensive pump). The alternative being to drop a hose all the way to the bottom of the tank might be impractical. 2. any reasonably sized pump would necessarily have to be close to the level of the tank to prime itself and also would have to pump the head ( increased vertical level) to reach overboard ( a messy visual image). Assuming someone has figured out a practical solution to this, you could give it a try but it seems futile to me and also it seems like a pretty messy alternative to doing it correctly.
RV tanks drain via gravity...boat tanks don't
Boat tanks have to pumped out using suction. There are a few that are installed to drain via gravity...they have be mounted completely above the waterline, which isn't easy to do on a sailboat. It CAN be done the way you want to...I know people who've done it, but the drawbacks outweigh the advantages: it's expensive 'cuz you'd need to buy the same kind of fitting that's on the end of a pumpout--one that has a cam coupler to link up with the same type fitting that threads into the deck fitting that's used at a pumpout. And you'd have to store that smelly hose and pump somewhere aboard. The system described in the Whale brochure isn't really that complicated. You COULD use just a tee in the pumpout line--which is what most builders use 'cuz it costs less than a y-valve...but a y-valve is recommended because it provides a means of shutting off the flow from the tank to service the pump. And a vented loop is necessary if the tank or any part of it is below waterline, 'cuz without it, sea water would rise to the waterline when the thru-hull is open. You can get away without one if you can mount the pump above the top of the tank, so that the pump becomes the loop. I dunno where you got the idea that a vented loop requires a hole in the deck though...it doesn't. So it's simple...y-valve, one side to the pumpout, the other to the pump...from the pump to the thru-hull, with or without a vented loop between 'em. If you use a macerator pump instead of a manual pump, it gets even easier to dump the tank...just open the thru-hull, turn on the macerator pump. Installation would be the same.
Boat tanks have to pumped out using suction. There are a few that are installed to drain via gravity...they have be mounted completely above the waterline, which isn't easy to do on a sailboat. It CAN be done the way you want to...I know people who've done it, but the drawbacks outweigh the advantages: it's expensive 'cuz you'd need to buy the same kind of fitting that's on the end of a pumpout--one that has a cam coupler to link up with the same type fitting that threads into the deck fitting that's used at a pumpout. And you'd have to store that smelly hose and pump somewhere aboard. The system described in the Whale brochure isn't really that complicated. You COULD use just a tee in the pumpout line--which is what most builders use 'cuz it costs less than a y-valve...but a y-valve is recommended because it provides a means of shutting off the flow from the tank to service the pump. And a vented loop is necessary if the tank or any part of it is below waterline, 'cuz without it, sea water would rise to the waterline when the thru-hull is open. You can get away without one if you can mount the pump above the top of the tank, so that the pump becomes the loop. I dunno where you got the idea that a vented loop requires a hole in the deck though...it doesn't. So it's simple...y-valve, one side to the pumpout, the other to the pump...from the pump to the thru-hull, with or without a vented loop between 'em. If you use a macerator pump instead of a manual pump, it gets even easier to dump the tank...just open the thru-hull, turn on the macerator pump. Installation would be the same.
Not a problem
Not my idea of a great solution but then it is not my boat either ;-) With that said you can indeed get a vacuum going on the pump-out fitting with your standard hand waste pump. The trick would be getting the deck fitting to hold the vacuum. You can probably Rub Goldberg a screw in fitting for the deck. Most of the ones I've seen have threads in the pipe. It would just be a matter of figuring out what size and thread pitch you need. For the record it is a little known fact that when you have moving water flowing past a hole oriented perpendicular to the flow there is reduced pressure. Witness the changing of the knot meter paddle wheel while underway. "Look maw no big gusher of water coming in?!?!?" Soooo, if you just add a Tee to the pump out line and plumb it through the sink drain with an additional valve to isolate it when you don't want the tank to empty into the sea through the sink drain thru hull....... You could develop a pump out drill. While on a strb/port tack (to get the tank as high as possible) and going above X knots (to get enough venturi suction) open the sink drain and then the holding tank drain. Wait for 3 minutes and then close the holding tank drain. I'd recommend playing around with an empty tank that you filled with raw water before trying it with the real stuff. some issues would be how much heel before the sink thru hull is exposed. this would be great for draining but probably stink to high heaven. also have a sink drain plug in place so the full venturi suction is applied to the holding tank. Lots of stuff to think through. If you holding tank is up high already you can do away with the vented loop on the discharge side and just use the tank vent. And don't forget about resale value. The next owner my not think your idea is so hot and it could actually end up costing you more than doing it the standard way. Good luck and let up know how you solved it.
Not my idea of a great solution but then it is not my boat either ;-) With that said you can indeed get a vacuum going on the pump-out fitting with your standard hand waste pump. The trick would be getting the deck fitting to hold the vacuum. You can probably Rub Goldberg a screw in fitting for the deck. Most of the ones I've seen have threads in the pipe. It would just be a matter of figuring out what size and thread pitch you need. For the record it is a little known fact that when you have moving water flowing past a hole oriented perpendicular to the flow there is reduced pressure. Witness the changing of the knot meter paddle wheel while underway. "Look maw no big gusher of water coming in?!?!?" Soooo, if you just add a Tee to the pump out line and plumb it through the sink drain with an additional valve to isolate it when you don't want the tank to empty into the sea through the sink drain thru hull....... You could develop a pump out drill. While on a strb/port tack (to get the tank as high as possible) and going above X knots (to get enough venturi suction) open the sink drain and then the holding tank drain. Wait for 3 minutes and then close the holding tank drain. I'd recommend playing around with an empty tank that you filled with raw water before trying it with the real stuff. some issues would be how much heel before the sink thru hull is exposed. this would be great for draining but probably stink to high heaven. also have a sink drain plug in place so the full venturi suction is applied to the holding tank. Lots of stuff to think through. If you holding tank is up high already you can do away with the vented loop on the discharge side and just use the tank vent. And don't forget about resale value. The next owner my not think your idea is so hot and it could actually end up costing you more than doing it the standard way. Good luck and let up know how you solved it.
Just thought of a way to test it
if the water level in the sink drain hose is below the bottom of the holding tank then you are golden. Most likely this is not going to be the case when you are not moving and the water is at the static level. If you take the sink drain hose off the bottom of the sink you should be able to determine just where the water level is while underway by just lowering the end of the hose till you see raw water. I'd hate to see you plumb the whole thing only to find you can't make it work. I actually have to deal with this when the reefer raw water pump is on and we are on a starboard tack. The pump and thru hull are "under water" but the venturi effect sucks the water down to where the pump looses prime. It is fine till the pump cycles off. I actually thought I had a gremlin in the boat cause I could not reproduce the problem once we got back to the slip. I got tired of hearing the admiral complain one afternoon and took the hose off and it sucked air?!?!
if the water level in the sink drain hose is below the bottom of the holding tank then you are golden. Most likely this is not going to be the case when you are not moving and the water is at the static level. If you take the sink drain hose off the bottom of the sink you should be able to determine just where the water level is while underway by just lowering the end of the hose till you see raw water. I'd hate to see you plumb the whole thing only to find you can't make it work. I actually have to deal with this when the reefer raw water pump is on and we are on a starboard tack. The pump and thru hull are "under water" but the venturi effect sucks the water down to where the pump looses prime. It is fine till the pump cycles off. I actually thought I had a gremlin in the boat cause I could not reproduce the problem once we got back to the slip. I got tired of hearing the admiral complain one afternoon and took the hose off and it sucked air?!?!
Actually the self pump out is standard ...
on several O'Days ... on the 272 LE there is a whale pump ... same model as the bilge pump ... mounted on the wall under the vee berth and a Y valve that allows you to empty the tank with the hand pump. If I remember you have the option of direct overboard, into the tank, and out of the tank ... Maybe two y valves. You also have the deck empty option. I don't think there is more than one vented loop and that comes from the head. Vic "Seven"
on several O'Days ... on the 272 LE there is a whale pump ... same model as the bilge pump ... mounted on the wall under the vee berth and a Y valve that allows you to empty the tank with the hand pump. If I remember you have the option of direct overboard, into the tank, and out of the tank ... Maybe two y valves. You also have the deck empty option. I don't think there is more than one vented loop and that comes from the head. Vic "Seven"
How' that again...????
" if the water level in the sink drain hose is below the bottom of the holding tank then you are golden." What would the water level in a sink drain line have to do with the location of a holding tank??? There's no common plumbing ...the holding tank can be anywhere in the boat--forward of it, aft of it, above the sink, lower than the sink, on the other side of the keel, and at a different height relative to the toilet or the sink.
" if the water level in the sink drain hose is below the bottom of the holding tank then you are golden." What would the water level in a sink drain line have to do with the location of a holding tank??? There's no common plumbing ...the holding tank can be anywhere in the boat--forward of it, aft of it, above the sink, lower than the sink, on the other side of the keel, and at a different height relative to the toilet or the sink.
Peggie
I think the post to which you referred was thinking the head a pump would have to push/pull as a function of how much below water level the tank was located. How that's relevant is arguable unless one wants to have the pump effluent located at the water level. Regardless, unless the pump is at or close to the tank level, this may not violate any laws of physics but sure seems impractical.
I think the post to which you referred was thinking the head a pump would have to push/pull as a function of how much below water level the tank was located. How that's relevant is arguable unless one wants to have the pump effluent located at the water level. Regardless, unless the pump is at or close to the tank level, this may not violate any laws of physics but sure seems impractical.
Not an expert but..............
I recently purchased a C25 with a fix head. I sail mostly on a lake without any pumpout stations. I purchased a small DC pump off ebay. I put a long clear hose on the intake end of the pump and shorter hose on the other end. I stick the long hose down the deck fitting and the other end in an old gas tank. I then use one of these portable handheld 12V battery to start cars with and connect it to the pump. I turn the pump on and drain the holding tank into the old gas can. This is just an idea, that so far has worked for me. Greg
I recently purchased a C25 with a fix head. I sail mostly on a lake without any pumpout stations. I purchased a small DC pump off ebay. I put a long clear hose on the intake end of the pump and shorter hose on the other end. I stick the long hose down the deck fitting and the other end in an old gas tank. I then use one of these portable handheld 12V battery to start cars with and connect it to the pump. I turn the pump on and drain the holding tank into the old gas can. This is just an idea, that so far has worked for me. Greg
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