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lupussonic 05-16-2012 05:07 AM

bilge pump system with mulitple bukheads???
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Hi there, I'm a brand new member here, although I have been reading threads for quite some time, info here has proved invaluable...what a resource!

My question for debate is as follows..
I am trying to design a bilge pump system for a 42' Zulu, rebuilt recently, that has 3 watertight bulkheads, hence 4 compartments. I have so far thought that all hoses that come from strum boxes in respective compartments should come to a manifold via taps. This means that if compartment 1 is filling, you open tap 1 and then choose your pump, open the tap to that pump (manual, electric or engine clutch pump), close taps to other pumps so water will not back down them, and Bobs your mother's brother. This was explained to me by a friend who worked on ships systems...

The problem arises when i am away from the boat and she springs a leak. When i am away, I planned to leave all compartment hose taps open, as i would not know where a leak might come from, and leave the electric pump on auto with float switches. BUT, if a leak occurs in compartment 1, and all hose taps are open, the electric bilge pump will also be sucking in air from the three remaining dry compartments...... see attached drawing....

This system also means that I should have 8, yes 8! float switches, one normal and one high water for each compartment!

Is there a way round all this?

sea_hunter 05-16-2012 05:58 AM

How about multiple pumps?

celenoglu 05-16-2012 06:37 AM

Re: bilge pump system with mulitple bukheads???
In my opinion watertight means watertight, which means no connnection of water to other compartments. Therefore it is best to design individual pumps for each compartment with their individual seacocks.

lupussonic 05-16-2012 08:11 AM

Re: bilge pump system with mulitple bukheads???
So how is it done on major ships with water tight bulkheads then? I am trying to build redundancy into the pump system, so I have manual, electric, and engine pumps available. aft in one compartment.. if i have a pump system for each compartment, that would mean 12 pumps (three for each), and four exit holes instead of one (manifold). Phew! Thats a serious pump system for a 40 footer....

lupussonic 05-16-2012 08:13 AM

Re: bilge pump system with mulitple bukheads???
But I take your point, well made, that if the four hoses are left open to the electric pumps while I am away, one compartment could flood another by backing down the next hose.....Doh!

sea_hunter 05-16-2012 09:00 AM

One compartment one pump. Each pump one auto/manual switch. You can limit through hulls with check valves. EG 2 pumps one TH or 3 pumps 1 TH. Easy.

lupussonic 05-16-2012 09:39 AM

Re: bilge pump system with mulitple bukheads???
Thanks for your reply...So I will end up with 4 electric pumps that handle the whole boat ( probably with their own batteries), and a manual and engine pump that only handles one compartment...? There has to be a way for the whole boat to be covered by one electric, one manual and one engine pump with canny piping. I have never had watertight bulkheads before, which I am glad to have, but the bilge system is foxing me! Anyone out there with bulkheads that have got around this problem with less pumps? thanks again Sea Hunter...

sea_hunter 05-16-2012 10:30 AM

Whoa there; batteries? Batteries need a charging system of some type; if you're a going to run wires for that you might as well just send them directly to the pumps. Sounds like you need a qualified marine electrician as induvidual batteries are not required for each pump.

lupussonic 05-16-2012 11:12 AM

Re: bilge pump system with mulitple bukheads???
I can wire up myself, but would rather solve the problem with fewer pumps and a better piping/hose system. Also, if I have 4 electric pumps, one in each compartment, and one compartment floods entirely it could short out the whole batt system. I would rather have all batts, pumps and taps aft, in one place and to hand. Not a big fan of having lots of non-return valves if I can avoid it as they clog, and consequentely cease to function. One electric, one manual, and one engine pump should handle it from the aft compartment, keeping electric lines short and everything to hand.

The question is the hosing layout which will not allow water into a dry compartment if another one floods, or allow air to be sucked up from a dry compartment when the float switch activates in a wet one...........hmmmm.....
I am trying to build in ease of use and redundancy, without 6 pumps and 8 float switches which seems excessive for a 40 footer!

Actually, there will be 2 manuals, 2 electrics and one engine pump but the song remains the to hose them with watertight bulkheads and leave the boat safe in the knowledge that the float switches and hose layout will kick in satisfactorily....

mitiempo 05-16-2012 12:41 PM

Re: bilge pump system with mulitple bukheads???

Originally Posted by lupussonic (Post 871776)
So how is it done on major ships with water tight bulkheads then?

Ships have crew to control pumping and manifolds 24/7 :)

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