Mul;tiple bilge pumps ?

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Boo2

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Hi,

I have inheirited 3 bilge pumps in my boat and there are some problems. 2 of the pumps are electrical (Rule 500/800 types) and one is mechanical. There is only one discharge fitting, high up on the transom.

There are some problems with the electrical connections which I intend to fix by means of glue heat shrink and heat shrink terminals but there is also an as yet undiagnosed problem with the Henderson Mk5 manual pump does not pump at full capacity.

My question is, how should all these pumps be connected up ? I intend to replace the electric pumps with higher capacity versions at a later date but in the interim I need to know what the ideal setup should be ? Is it acceptable for the electric pumps to be plumbed in series with the manual one (I presume not) ? Otherwise there will need to be some kind of outlet manifold, but how do I ensure that operating eg the manual pump doesn't back flush the electric ones ?

Anyone know a website where all this is explained, or care to attempt it here ?

Thanks,

Boo2
 
So long as each pump has a functioning non-return valve in it's outlet side I can't really see a problem, whichever one is pumping, the bilge water will only be able to go one way - overboard.

Do you mean to connect the discharges of the electric pumps to the suction of the manual pump? If so, you will need isolating valves (I'd use full bore ball valves) somewhere on the electric pump discharges otherwise the manual pump will suck from both of them, and once the bilge level falls below the highest suction you will only pump air...
 
Anything you connect on the discharge side of your electric pumps, either a check valve or the manual pump, which is effectively a double check valve, is going to severely restrict both their flow and head. Recent tests in PBO showed none of these cheaper pumps to perform particularly well, rarely meeting the specified values for a variety of reasons.

The ideal way is to connect each pump to its own skin fitting but I can see that you might not want to do that. I would keep the manual one separate, taking advantage of the fact that it will prime itself, which the others won't unless immersed. You could experiment with putting one electric pump ahead of it to see whether it will still function effectively but these pumps make pretty poor strum boxes.

I would definitely have at least one electric pump, the biggest, piped to its own outlet, sited as close to it as possible and with the least head you can safely get away with. A siphon loop is good, as its head can be ignored as soon as the column is full. My manual and electric pumps are piped this way (separately), with skin fittings at water level.
 
If they are all in series, it will inhibit the performance of all of them. It is not unuaual, particularly on a small boat with little lift to achieve, for an electric pump to be mounted in series with a manual pump as the losses are acceptable for the task in hand. But there is a school of thought that the smaller the boat the bigger the pump required as a given amount of water shipped is more likely to sink the smaller vessel.

I would be inclined to pipe the outlet from the electric pumps to a Y joint and then to a new, shared skin fitting. If they both have one-way valves, they can then work independently. Put a strum box on the manual pump (I assume the electric pump strainers were being used as substitutes) and the performance should revert to full capacity. That gives you a first level of redundancy in your safety system.

Rob.
 
If there are two electric pumps, pumping the same space, I also like to have one on a float switch for its auto setting and one on a solid state switch for its auto setting, so you get the best of both worlds in terms of redundancy.
 
The problems are I believe that the Rule pumps do not have not return valves. Although the manual pump, by virtue of its design, does.

The Rule pumps if connected to the same outlet can simply back flush each other unless they operate together on the same float switch or similarly placed individual switches

The manual pump will simply back flush the Rule pumps if it is connected to the same outlet.

On the face of it non return valves fitted in the outlets of the Rule pumps will allow all three to discharge via the same outlet.

BUT if a non return valve is fitted to the outlet of a Rule submersible pump it may not re-prime against the head to a high outlet if it looses it prime.

However I think non return valves fitted in the individual Rule discharge hoses close to the common outlet, or at least some distance from the pumps, will work.
 
When you really need your pumps you want them to have their own outlets. The smallest Rule pump can have a check valve close to the pump. This will allow removing as much water as possible without it running back to the bilge. This is the everyday pump and will get the most use. It could have its outlet in the cockpit above a drain. The second larger electric pump should have a dedicated outlet and not have a check valve for max flow. Loop the outlet high and then down to its through hull on the transom about halfway from the waterline to the deck. The manual pump should have a strum box and its dedicated outlet, also with a loop high up before going down to the outlet.
 
Go for separate outlets. Not hard to fit through a normal fibreglass hull - holesaw and a bit of sikaflex and job done. I inherited KS with a single manual pump, and when I added an electric it never occurred to me to do anything other than add its own outlet.

When I was on a charter yacht that flooded off Falmouth, we had all three pumps going (and buckets!) and I wouldn't have wanted to think there was a restriction in the outlets that day.

Pete
 
prv said:
Go for separate outlets. Not hard to fit through a normal fibreglass hull - holesaw and a bit of sikaflex and job done. I inherited KS with a single manual pump, and when I added an electric it never occurred to me to do anything other than add its own outlet.

When I was on a charter yacht that flooded off Falmouth, we had all three pumps going (and buckets!) and I wouldn't have wanted to think there was a restriction in the outlets that day.

Pete
Click to expand...

If you do fit another outlet, the plastic skin fitting may require a backing pad to stop the hull flexing and breaking the fitting.
 
+1 for one pump one outlet. If one set fails for any reason then the others are independant and should wrok. I'd be minded to have the electrical pumps having independant switches auto/manual with a dedicated power supply to each (I mean each connected to a separate battery).

Call me over cautious if you will. I pulled out of an SI training day because one of the three circuits to my electric pump was faulty. The day would have meant spending time swimming in overfalls I considered one backup insufficient.
 
bilge pump thoughts..

check the diameter of hose needed for the smaller of the rule pumps and see if you could tee it into a galley sink outlet or airconditioner waste water outlet. you definitely dont want 2 or 3 bilgepumps all trying to pump water out thru the same outlet. if you put the outputs of the 2 rules flowing together via a y or tee into the same outlet you will lose a tremendous amount of head. if the purpose of the manual pump is only to serve as a backup if the electrical bilge pump fails, you can safely leave the manual plumbed into the same outlet as the larger rule pump. note that the rules will allow the water in the exit line to come back into the bilge when the bilge pump quits pumping. it is not recommended to put a one way valve in the outlet line of a bilge pump as they can clog. in the USA, surveyors will fail a boat with one way valves in the exit lines of bilge pumps. if you dont like the h 2 0 backflusing back into the bilge from the rules, you can swap out the rule style for a belt drive par jabsco diaphragm pump which costs significantly more money but lasts 20 years...
 
I wouldn't T a bilge pump outlet into a sink drain as when heeled the T may be underwater and become an inlet - the pump will not restrict it and I wouldn't depend on it in any case.

If you have 2 electric pumps, the smaller can be mounted the lowest and be considered the daily maintenance pump and it can have a check valve in the output. I have never seen a surveyor complain about that. The larger pump should be mounted a bit higher and should not have a check valve, mainly because it will reduce flow.

I wouldn't ever use one outlet for more than one pump as it you really need to remove water fast 2 electrics and one scared sailor on the manual can move a lot of water - this will not work with shared outlets.
 
eagleswing said:
if the purpose of the manual pump is only to serve as a backup if the electrical bilge pump fails
Click to expand...

If you have a significant quantity of sea on the inside where it doesn't belong, you're going to be pumping hard on everything that can possibly shift water, not ruling out some pumps as mere "backups" to others. Been there, done that.

Pete
 
prv said:
If you have a significant quantity of sea on the inside where it doesn't belong, you're going to be pumping hard on everything that can possibly shift water, not ruling out some pumps as mere "backups" to others. Been there, done that.

Pete
Click to expand...

Absolutely right. You want a big Gusher or better, mounted where you can pump without effort for an hour. This means where you can operate it standing up, using a rocking motion. Believe me, and presumably prv :), shifting a lot of water through a 1.5 inch pump takes lots of effort and the manual one will outperform most cheap electric pumps by a considerable margin.
 
vyv_cox said:
Believe me, and presumably prv :), shifting a lot of water through a 1.5 inch pump takes lots of effort and the manual one will outperform most cheap electric pumps by a considerable margin.
Click to expand...

Fortunately we'd completely sealed the leak so weren't battling against incoming water, only removing what was there. Also fortunately, we were fully crewed so had one person on the manual pump in the cockpit, one on the manual pump below, two people bailing with buckets, and the electric pump on. Not scary at any point, just very inconvenient - as well as wet bunks and clothes, the water rising under the chart table took out the "brains" for the instruments so for the rest of the week we had no GPS or wind/speed/depth.

Would have been scary if it had been hull damage we couldn't fully seal, rather than a transducer fitting that was quickly bunged. Also if we'd had only a single pump, I'd have been very conscious that we'd be in trouble if it failed.

Pete
 
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