bilge setup question

[doctom]

i couldnt find anything directly addressing this question in the archives but maybe someone could give me an opinion....
i have a cheoy lee offshore 33. the bilge has basically two levels, one in the engine compartment below the cockpit and another deeper in the cabin sole. i have a auto bilge pump in the cabin bilge and a larger one for the engine bilge. the PO set it up so the cabin bilge was pumped into the engine bilge and the engine bilge pump went to the above water through hull. There is only one above waterline through hull. There is a manual bilge that empties via a thru-hull just below the water line.
i would like both bilges to empty off the boat. i thought about a y valve with a flapper. or could i run the bilge through the manual pump (t is a diaphragm type)? should i leave the setup as is? or must i really carve another hole in the side of my boat for another dedicated bilge through hull? the boat has another thru hull for the holding tank access as well as one forward for the AC outlet.

thanks in advance,
mike

[TrueBlue]

My boat has only one high capacity bilgepump with float and manual switches and a dedicated through-hull - above the waterline. There is also a Whale manual diaphram bilge pump with a dedicated through hull, located alongside the other.

When I installed a shower sump box, with an integrated float switch and pump, I also connected a Y-valve onto the manual pump outlet hose - just before it exits the hull. The shower sump outlet hose is connected to the other Y end. I located an extended Y-valve handle next to the manual pump handle - for easy access in case of an emergency.

I suppose you could do something similar with the upper bilge pump valve always directed overboard. Then, switch the valve to use the emergency manual pump.

[LazyGuy]

One of my hand bilge pumps dumps into the cockpit drain. It is T so I need to install a wood plug into the cockpit drain to use the normal, manual bilge pump otherwise I get bilge water into the cockpit. My high capacity electric bilge pump which operates on a float switch and my gusher T into the same above waterline outlet. The manual pump is well above water line and the electric has a loop that takes it well above waterline. I do not see any problem with a T from two bilge pumps as long as they discharge above the waterline. The manual goes straight through the T to the discharge and the 2K goes into the side of the T.

Cheers
Dennis

[T34C]

Ideally the smaller pump should have a seperate thru-hull. That way you can use a smaller ID hose between the pump and the thru-hull and reduce the amount of water that runs back into the bilge when the pump shuts off. The run between the pump and the thru-hull should also be as short as possible.

[sailingdog]

Originally Posted by LazyGuy

One of my hand bilge pumps dumps into the cockpit drain. It is T so I need to install a wood plug into the cockpit drain to use the normal, manual bilge pump otherwise I get bilge water into the cockpit. My high capacity electric bilge pump which operates on a float switch and my gusher T into the same above waterline outlet. The manual pump is well above water line and the electric has a loop that takes it well above waterline. I do not see any problem with a T from two bilge pumps as long as they discharge above the waterline. The manual goes straight through the T to the discharge and the 2K goes into the side of the T.

Cheers
Dennis

The high loops aren't recommended for most bilge pumps... the higher the pump has to push the water, the lower the amount of water it can push. Most pumps are rated with zero head—meaning that the water they are moving is not being lifted, but moved horizontally. While pumps should discharge above the waterline, they should do so without having to lift the water any higher than necessary.

[SimonV]

I would say the reason for the cabin bilge, pumping into the engine bilge and then out, would be the cabin bilge will self siphon after being turned off giving you a very dry cabin bilge. Also if you empty the engine bilge in a NDZ you might end up with the EPA calling by due to the oil slick.

[hellosailor]

Mike, the only "proper" way to dump bilge pumps is one pump, one hose, one exit fitting. Partly to ensure they don't fight each other, partly to ensure one failure can't block it all. So it you want both to pump overboard...spring for the extra plumbing, among other things it will keep insurance surveyors happy.

I suspect that your PO rigged things this way because the lower pump does not have enough lift capacity to lift water all the way from the bottom UP to deck level so it can loop and then exit the boat. You would need to measure the distance from the bottom up to the top of your loop (and as mentioned you definitely want a high loop) and then see what kind of pump capacity you can get for it.

There will also be another drawback--that whenever the pump shuts, the "slug" of water in that large hose, making that long run all the way up, is going to drop back down into the bilge--leaving lots of bilge water.

The kludgy 2-stage design you have probably also cuts that amount of water in half. So, there are plusses and minuses, and I'd guess the PO did this compromise with them in mind. (Not really the right way to do it, but...)

If you have to use a big pump with a long run, resulting in a large slug of water coming back into the bilge, the only real way that I have heard of dealing with that is by using a second VERY small pump--designed to suck up that last inch of bilge water, slowly but thoroughly, with a small diameter hose. (Yeah, three hoses, just what you didn't want to hear.)

Well, the alternative is learn how to roll the boat quickly so it spills out the companionway.