How connect two bilge pumps to ione thru hull

[OS2Dude]

No need to be nasty. He asked a question (Which is how we ALL learn). If you can't give a useful, constructive answer then please don't respond at all.

[john61ct]

Did not see anything nasty.

Important safety information is best delivered emphatically

[Taipe]

Why you want to eliminate one of your bilge pumps? You can never have enough bilge pump capacity.

In addition to having two electric pumps, you ought to have a manual high flow double-action pump operated from the cockpit.

Also, unlike what we find in the discharge location in most boats, and particularly important for sailboats, the diameter of the discharge thru hull should be an extra wide I.D. located aft, at or near the midline, and as high above the waterline as possible. A full-bore ball valve can be threaded onto it with a 'T' for tail pieces on each end to the discharge hoses. If using bronze, this results in a fairly heavy setup, so using Marelon for the 'T' & tailpieces reduces the weight considerably.

[rbk]

Originally Posted by pcmm

And NEVER discharge into the cockpit. least of all because bilge water occasionally get a bit oily. will make a mess on the floor and this way you are also dependant on the scuppers being clear.

This theoretically being the emergency bilge pump with water being at/near my floor boats (250-300 gallons of water in my bilge at this point) I wouldn’t be worrying about any oil (my bilges are clean btw as should everyone’s else’s, there’s really no excuse outside major mechanical emergency or lazziness) it also depends on your cockpit design. This is not something I worrying about in my boat.

[Mango51]

I have the emergency Manuel pump loop up around 4 feet above the water line. Exits two inches above waterline. My first electric bilge pump loops the same way on a smaller hose and tees on the exit side down hill after loop. Of the Manuel pump. Then high water pump with alarm same style loop on its own hose.

[Oceandeep]

I would really think about that before I made the change. I really think each pump should have their own thru Hull.
My boat came equipped as you describe. 2 big pumps feeding to a manifold with one way valves. Nothing but trouble. Sometimes one of the valves would stick. Sometimes one pump would over power the other pump and send the discharge back to the bilge.
Every tome there was a problem I effectively lost 2 of my best bilge pumps. No redundancy. My 2 cents is to have two separate systems- pump, hose, control switch and thru Hull. Then you have redundancy if one pump fails

[roverhi]

My bilge is split by the center board trunk. The two sides of the bilge are connected so on an even keel water flows from one side to the other. When the boat is heeled sailing water will not get to the high side until there is a lot of water in the bilge. With only one bilge pump better hope the leak is on the side with the pump or you going to have water sloshing on the cabin sole. Solved the problem by having a pump on each side of the trunk. The 3/4" hose from the pumps run to a 1 1/4" stand pipe with a loop well above the heeled water line with an anti-syphon valve at the top of the loop and rubber flapper check valve at the pump to keep the water from the relatively long hose run from flooding back into the bilge. If the boat is heeled sailing, the low pump will work with water ingress and only involve the high pump if there is a lot of water in the bilge and coming in fast. The rubber flapper check valve cannot fail closed and actually have found that they aren't all that good at stopping back flow over time. The the flapper tends to take a set and doesn't seal after awhile. Inverting the flapper will temporarily restore the sealing capacity but eventually the flapper takes a bad set for the new orientation. The bilge sump has a generous fairly level area so the water flowing back down the hose doesn't cause cycling shutoff problems with pump shutoff and hardly raises the residual water level in the bilge so not an issue if they don't seal.

[boatpoker]

Originally Posted by J.Kitchens

Maybe you should check the ABYC standards for bilge pumps and share your idea with your insurance company.

Sound advice, the idea is not ABYC compliant.

[SVTwilight]

I had two into one and it never worked well.

Ended up adding a through hull.

Bilge pumps are important. I would leave them separate....

Originally Posted by xxhat

Want to eliminate one thru hull.


Right now each bilge pump has its own thru hull.


Was thinking of eliminating one by having each pump go to a sea chest then the sea chest goes to the thru hull.


What are others doing ?


How else can I eliminate one thru hull ?


maybe by having one pump go to the cockpit ?


Thanks


jim

[Olddan1943]

One pump, one through hull 1 to 2 ft above the boot top
No check valves, they can jam
End of story.

[Uncle Bob]

Originally Posted by J.Kitchens

Let me spell it out for you.

The boat is sinking. This fact causes the water level to rise in the sea chest. The water has no place to go once it fills up the sea chest so it goes into the bilge pump lines. Once the lines are full the sea water will back flow out of the bilge pumps.

Please , just how is this any different to a single bilge pump connected to a single skin fitting in the same location, discharge line going up from fitting and then down to the pump? Would the result not be the same in the same scenario?
My boat has one skin fitting per pump and I agree that is the way it should be, however the concept of a seachest type device, appropriately sized discharge fitting, located high in the hull really is not that different to a riser loop between the pump and discharge fitting. Bear in mind that a seachest type device would be sealed except for input and discharge lines.

[FlightPlan]

Each of the bilge pumps should be installed as low as possible so they don't have to lift water to the pump. Each pump should go to an anti-siphon loop fitting high enough above the water line to break the siphon on the discharge side of the loop. If done this way, there is no reason to discharge oily dirty water down the shear of the boat, I like to keep that clean, as well as my cockpit.


I also would set my small pump float at 1" above the low point, and my larger pump float around 4" above the low point. Thus the little pump does the housekeeping work and the big pump does the heavy lifting.


What is wrong with thru hulls? I've got 13 total and three bilge pumps.

[GILow]

Originally Posted by rbk

You think that’s entertaining? Someone started an ‘exterior varnish’ thread, better get over there and claim a seat lol

Ha ha. I know my limits! [emoji846]

[GILow]

For the OP, I understand and applaud the desire to eliminate through hulls.

But in this case I vote with keeping things simple.

In my boat I have two electric bilge pumps and one manual.

As someone posted higher up, a small 12 volt “housekeeping” pump, a very high capacity 12 volt “oh sh*t!” pump and a manual “shut up and keep cranking” manual pump in the cockpit.

Each with its own hose to the stern of the boat with an anti siphon loop to just under the rear deck height and a skin fitting about 3 inches above the static waterline. No check valves.

When I first considered how to set up the boat pumps from scratch I looked at the single through hull option and came to the conclusion that the possible modes of failure far outweighed the trivial risk presented by three new, good quality skin fittings set above the waterline.

Like a lot of things in boats, getting too clever is sometimes not clever at all.

[Aaaskypilot]

I have 2 Rule 2000 on my 32 ft. Gulf, both have check valves about 10” away then go to aY fitting & out to the back thru Hull ... Each is wired on separate circuit thou for the safety back up if one were to fail in use