Vented loop necessary?
- Thread starter Project_Mayhem
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It would probably be best to install a loop that goes well above the water line at any heel angle. This doesn't need to be vented, just high enough so water can't back into the hose when the boat is heeled.
I'm installing a small pump to suck the last bit of water out of the bilge. It's always wet, stuff is growing in there and it stinks!
I plan on installing a non-vented loop that's about 2' above the water line at its apex and a check valve. I know the latter isn't necessary and in some cases can fail open or closed
You are pumping water from your bulge and dumping through the sink - so that line has no external access to the boat? I don't think it needs to be vented. That would be for anti-siphon from the outside. Doesn't sound like that would be your case. Sounds like the anti-siphon would be the space between where you are dumping into your sink and the line. I do question dumping bilge water into your sink however. Not sure it's the best place but I don't know what options you have on your boat. Why the one way valve? And where are you putting it?
dj
dj
The need for a loop depends on where you ingress the drain hose. If you enter the drain hose just below the sink, then as long as you are not within a few inches of taking on water through the sink drain when you heel, you will not take on water through this hose. But, if that ingress point would put you close to the waterline in a strong heel, then a loop would help.
If you planned to ingress that drain hose quite low to minimize how far you would have to pump, then that is false economy because you would still need the loop that goes above the waterline. Otherwise, you risk taking on water in a heel. So, you will need to pump the water that high no matter what.
This subject comes up a lot - folks who want to get more water out of the bilge than a normal setup will accomplish. My advice has always been to just accept that there will always be some water because any solution brings more trouble than its worth. (Easy for me to say with my relatively shallow bilge that pumps nearly dry.)
But, just this summer I saw a solution that was kind of brilliant. The guy had two pumps - his main pump and a smaller pump with a 1/4" hose intake. The float switch was wired to prevent the smaller pump from operating while the larger pump was running. I don't know what triggered the smaller pump - presumably a moisture sensor of some sort, though I neglected to ask. Anyway, the pump just emptied into a gallon jug that sat in the bilge and he emptied it out every so often (about once a month, he said). If it overflows, it just overflows back into the bilge. I don't know what prevented it from just continously cyling, should this happen (like a backyard waterfall), but he was really happy and his bilge was nearly bone dry.
If you planned to ingress that drain hose quite low to minimize how far you would have to pump, then that is false economy because you would still need the loop that goes above the waterline. Otherwise, you risk taking on water in a heel. So, you will need to pump the water that high no matter what.
This subject comes up a lot - folks who want to get more water out of the bilge than a normal setup will accomplish. My advice has always been to just accept that there will always be some water because any solution brings more trouble than its worth. (Easy for me to say with my relatively shallow bilge that pumps nearly dry.)
But, just this summer I saw a solution that was kind of brilliant. The guy had two pumps - his main pump and a smaller pump with a 1/4" hose intake. The float switch was wired to prevent the smaller pump from operating while the larger pump was running. I don't know what triggered the smaller pump - presumably a moisture sensor of some sort, though I neglected to ask. Anyway, the pump just emptied into a gallon jug that sat in the bilge and he emptied it out every so often (about once a month, he said). If it overflows, it just overflows back into the bilge. I don't know what prevented it from just continously cyling, should this happen (like a backyard waterfall), but he was really happy and his bilge was nearly bone dry.
I've done the same thing for a small sump pump (it does not actually dump into the sink, it tees into the pipe a few inches below that). It saves a thru-hull and since the sink is well above any heeled waterline, that is the vented loop. The flow is low and it comes in at such an angle (hose it routed high, up under the countertop) that sink drainage is not impeded and it does not back up into the sink. Works fine.
Do make sure the sink drainage can't go back to the pump.
The way I do it is a 1 gallon craftsman shop vac and a sponge. The shop vac comes in handy for so many things other than drying the bilges too.
To reiterate, the question isn't is a loop necessary but is a vent necessary at the top of this loop. The pump's output is Tee'd into the sink drain so it would seem that the open drain would function as a vent. The Tee is just below the waterline. In addition, the engine and stuffing box have a separate area which fills up with water. The oil pan is partially submerged at all times so I plan on running a hose to get rid of this water as well.
It dumps into the sink drain line through a Tee fitting and then travels down 18" of hose to the through hull. Most other through hulls are intakes on my boat. I'd prefer not to give the other pumps dirty bilge water. The check valve is just extra piece of mind. I could put them on the intake side so water doesnt rush back into the bilge when the pump turns off (this might be a good idea to avoid constant on/off cycling). The check valve on the output side aren't really needed since I plan on doing a loop as high as possible in this cabinet. The question wasn't does it need a loop, but does the loop need to be vented
This is the exact same setup I'm planning on doing. On a rare occasion in heavier seas, we have seen water come up through the sink drain. I installed a check valve to reduce backflow as a loop for this isn't practical. The housing of it is clear and there's a lot of play in the bullet shaped "stopper" inside. I'm guessing it'll reduce backflow by 70-90%. The small pump to get the last of the water out of the bilge it Tee'd below this check valve. Thank you for a straightforward answer. It's much appreciated!
Minimizing boat prep and cleanup maximizes sailing time. Our stuffing box and engine have a separate section that holds 3-5 gallons. I plan on running a line to get rid of this water so the oil pan isn't submerged. We don't have shore power. I do keep a 12v dust buster on board
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The water in the sink can go down into the bilge if the water in the sink is above the entry point of the bilge water hose, without a loop. You can't use a check valve if you are using a centrifugal pump from the bilge, period. The centrifugal pump does not produce the pressure to open it.
You can't use a poppet (spring) check. They also tend to clog. A swing check will work, since they require practically no opening force. Their are types that are very clog resistant and are commonly used for bilges, sumps, and even wastewater.
Do note that in cold climates (the OP is in Chicago) a check valve will allow the water trapped in the hose to freeze, blocking the pump. Something to be aware of in the main bilge pump, if the boat is ever in the water when the air is below ~ 25F. Without the check valve, the water will drain into the bilge, where the water the boat is floating in will keep it from freezing. The moral is that check valves are designed to trap water, which can freeze.
I'd sail into December if I could but sadly, the marina's dont stay open past November 15th and that's with an extended permit that you have to pay extra for
Is your sink drain always above the water line at all points of sail? If no - it needs to be vented. If yes, then no you don't. That's the simple answer. I would want to look carefully at using a one way valve.
There are systems used to keep dry bilges. I'd have to look them up...
dj
There are systems used to keep dry bilges. I'd have to look them up...
dj
I admit to being real nervous about leaving a 'sink drain' thruhull open all the time.
We have no below-DWL entry point for water, having a PSS shaft seal, but do have a keel-stepped mast. So in the winter, after a rain storm, I visit the boat and dry out the bilge with............ a turkey baster! Bilge is bone dry all summer. Not a solution for everyone, but it has worked for us for 25 years.
It's irrelevant if the sink drain is always vented inside the boat. The question is if it remains above the waterline on all points of sail. The function of a vented line is that the vent sits above the water line on all points of sail such that a siphon cannot be established. But in this case, it actually would not matter where the sink drain is - it's where you make the attachment - if that attachment point is, or can be, below the water line, you are establishing the conditions for a siphon.
dj
The simplest solution is a plug in the sink. Walmart sells a package of rubber plugs in 3 sizes dirt cheap...one of them will fit.
Incidental water that collects in the bilge as a result of ongoing spills and leaks is usually clear, but stagnant water being pushed into the bilge is a different issue. The average sailboat will have multiple gallons of water trapped in the hull stringers bellow the sole. That trapped water gets stagnant and with the growth of bacteria and decay matter it will stink. This trapped water will usually escape to the bilge as the boat heels or moves around when underway. It could also be displaced by new water entering the stringers area. Determine if the fouled water coming out is because the boat is infrequently used or if it may be excesive water leaking in. Installing a pump may only extract the fouled water being released but will not take care of the major infestation. Some sailors dump a chlorine solution or cleaners into the high sides of the inside hull and then go out for a brisk sail, hoping to flush out the trapped stagnant water to the bilge. A marine safe product should be used to discharge into the waterways. Lastly a bilge is designed to have a little standing water that the bilge pumps are unable to suck up as it will block the smells from invading the cabin. In my book, dry bilges in other than brand new boats are a no-no. A fun-fact is that if you are taking a long trip usually by the 2nd day at sea you will no longer smell the foul odor. Curing and drying up the stagnant water sipping into the bilge may take a week or more depending on the size of the boat and the effort applied, just to have to periodically repeat the procedure. Just keeping the animal caged and away from the nose is at a lot easier.