Curious Case of Bilge Pumps that can't reach the top!

[Degobah Schooner]

Hello everyone,
Wishing you well.

Got a question with pictures!

I installed 2x bilge pumps on either side of an engine bay, connected to a T JUNCTION going to the waste OUT. 25mm internal diameter on pipe, classic transparent PVC Flex reinforced, matching the old original waste pipe size. All fittings snug with jubilee clips. Original single pump worked OK. Yet now both pumps can't get the waste water up to the top of the pipe, never mind out the waste. What would anyone recommend? Thinking -  simply, get narrower pipe? (Available in 5mm interior diameter - 51mm so can defo get thinnner). Also thinking when it can draw to the top, the T-JUNTION likely won't work as one pipe may drain to the other descent to other pump at the T and miss the outlet, so may switch position of TJUNCTION before OUT. SEE PIC for Ref. Thanks in advance one and all!

[David Mack]

Do you have non-return valves fitted? Are both pumps running at the same time? If you run only one pump with no NRVs fitted the water will be running back down and through the pump that isn't running.

The easiest option may be for each pump to have its own skin fitting outlet.

[Alan de Enfield]

Could it be there is not enough water ?

 

Disconnect one of the pumps from the T and connect it directly to the skin fitting - does that work ?

 

Why 2 pumps ?

Are the two sides not connected (limber holes at the stern beneath the engine bearers ?

[ditchcrawler]

2 minutes ago, Alan de Enfield said:

Could it be there is not enough water ?

 

Disconnect one of the pumps from the T and connect it directly to the skin fitting - does that work ?

 

Why 2 pumps ?

Are the two sides not connected (limber holes at the stern beneath the engine bearers ?

Our last boat wasn't, the engine bearers went from the bulkhead to the swims with a divider to make a bit under the prop gland. The pump was in the bit under the gland and I bailed/mopped out the side sections 

[pearley]

6 minutes ago, ditchcrawler said:

Our last boat wasn't, the engine bearers went from the bulkhead to the swims with a divider to make a bit under the prop gland. The pump was in the bit under the gland and I bailed/mopped out the side sections 

Mines like that now. As it's a trad stern the water can only come from rain blown through the engine air intakes which are about 1 1/2 metres from the stern. I taped over them last winter and bilges either side of the engine remained dry so will have to look at some permanent means of prevention.

[Degobah Schooner]

Thanks for all the responces!

• No non-return valves fitted - Did not know they were available for such waste pipes, could be good. Will research, but any one used before/know where/name?
• Both pumps operate/are planned to be on auto setting at the same time all the time.
• One pump when operating, running down to the other pump - this is my worry hence, the adjustment of T suggestion on drawing.
• Each pump to have its own skin fitting outlet suggestion - too invasive, don't want to cut another hole.
• Could it be there is not enough water ? YES, but want to keep it relatively shallow and the amount of water needed to get the rise is too much.
• Disconnect one of the pumps from the T and connect it directly to the skin fitting - does that work. - YES this works.
• Why 2 pumps - Requested and the two sides are largely seperated, and fill at different rates, hence pump installed for each side.

Seems like there's many ways to go about this, any thoughts on the skinnier pipe to increase suction?

 

 

[Tracy D'arth]

3 minutes ago, Degobah Schooner said:

 

• Disconnect one of the pumps from the T and connect it directly to the skin fitting - does that work. - YES this works.
•  

Seems like there's many ways to go about this, any thoughts on the skinnier pipe to increase suction?

 

 

Thinner pipes will make no difference.

If one pump on its own works then that is the answer, isolate the waste pipes from one another. I am not a fan of non return valves in waste pipes, they get clogged.

If you take both pipe up higher than the skin fitting like swan necks then down to the fitting with the tee still above the skin fitting it should work as each pump can drain separately.

[Degobah Schooner]

Thanks Tracy, yes I was thinking of something like that, like a washing machine waste. Will give it a go but don't want to isolate each pump - so still going to puzzle this; as would like to try to have both pumps on auto, can run at the same time or singly and out of the same waste outlet.

[ditchcrawler]

1 hour ago, Degobah Schooner said:

Thanks Tracy, yes I was thinking of something like that, like a washing machine waste. Will give it a go but don't want to isolate each pump - so still going to puzzle this; as would like to try to have both pumps on auto, can run at the same time or singly and out of the same waste outlet.

Leave them on auto and the first pump to cut in will pump all the water to the other side, when that happens the other pump will start and while both run it will go over the side, but once one stops it will just jeep transferring one side to the other until your batteries are flat

[Arthur Marshall]

Battery power? I know if the water pump is running for a shower and I turn on the shower pump the water pressure drops immediately. Is there enough power to run both pumps fast enough to get the rise? Bilge pumps are pretty wimpy things.

Edited February 17 by Arthur Marshall

[David Mack]

30 minutes ago, ditchcrawler said:

Leave them on auto and the first pump to cut in will pump all the water to the other side, when that happens the other pump will start and while both run it will go over the side, but once one stops it will just jeep transferring one side to the other until your batteries are flat

Or more simply, arrange the pump on one side to simply pump to the other side, and the pump on that side to go to the outlet. With both on automatic each will cut in and out in its own time when necessary to empty its own side. And a single outlet pipe from the second pump which the OP knows works.

2 hours ago, Degobah Schooner said:

Both pumps operate/are planned to be on auto setting at the same time all the time.

That will only happen if you have a single float switch controlling both pumps. If they each have their own float switch they will cut in and out at different times depending on the water level each side, the different mounting heights and trigger points of the two switches and any list of the boat.

[magnetman]

3 pumps and a bucket. 

 

Two auto pumps discharging individually to the bucket. One auto pump in the bucket discharging to the skin fitting. 

 

 

[Peugeot 106]

5 hours ago, magnetman said:

3 pumps and a bucket. 

 

Two auto pumps discharging individually to the bucket. One auto pump in the bucket discharging to the skin fitting. 

 

 

yes but if the pump in the bucket fails you are stuffed if the object of having two pumps is to allow for redundancy

Or simply a hopper higher than the skin outlet  so that the hopper gravity drains with each pump separately pumping into the hopper. Then either pump can fail.  
As drawn won’t work without non return valves which are an added thing to clog unless they are integral (inbuilt) in the pump which I very much doubt.

 

[Rincewind]

Please tell us.........we would love to know,

Just how many of you are related to Heath Robinson?

   

[blackrose]

T-ing waste hoses together is often problematic. You've said when you connect one of your bilge pumps direct to the skin fitting it works, so that's confirmed the problem is T-ing the hoses together.

 

I don't understand why cutting a hole for another skin fitting is "too invasive"? It's just a skin fitting. Unless you really mean you're scared to cut a hole in your hull? It's understandable, plenty of people are, but as long as you measure carefully it's not major boat surgery. You've already got the existing skin fitting to show you the correct height.

Edited February 18 by blackrose

[magnetman]

Make the existing hole bigger then fit two skin fittings to a brass disc then bolt the disc over the hole and fit the two hoses. 

 

 

[Tony Brooks]

3 hours ago, blackrose said:

I don't understand why cutting a hole for another skin fitting is "too invasive"? It's just a skin fitting. Unless you really mean you're scared to cut a hole in your hull? It's understandable, plenty of people are, but as long as you measure carefully it's not major boat surgery. You've already got the existing skin fitting to show you the correct height.

My thoughts also, but I would want to take care to site the fitting close to a rubbing band to protect it from the possibility of having the head knocked off in a lock. A hole saw in a drill with plenty of lube will do the job, even if it takes a while.

[magnetman]

It would seem logical to have a skin fitting on each side in the same location.

 

Must say I do like the raised hopper solution put forward by @Peugeot 106

For the bucket and 3rd pump setup the idea would be to have a second separate float switch higher up than the pump wired to the pump manual control wires via a relay. So if the float on the pump itself failed then the second float would sort it out. Wire a third float switch to a flashing warning LED somewhere indoors to give notice if the bilge pump float fails. 

 

 

 

OR sort it out so that water does not enter the bilges. 

 

Maybe tricky if it was a wooden Boat. 

 

A bit odd that the bilge areas to the sides do not communicate with the bilge area beneath the stern gland. 

 

Obviously this is a rain ingress story. 

 

 

 

 

[Peugeot 106]

7 hours ago, Rincewind said:

Please tell us.........we would love to know,

Just how many of you are related to Heath Robinson?

   

I for one sometimes wish I was. Most of his lashups seemed to work

[blackrose]

24 minutes ago, magnetman said:

Make the existing hole bigger then fit two skin fittings to a brass disc then bolt the disc over the hole and fit the two hoses. 

 

 

 

Making an existing hole bigger sounds like more trouble than cutting a new hole. Come on, it's not brain surgery, it's just cutting a hole and putting in a skin fitting. I've probably done over a dozen on various boats. It takes a while to cut though 6mm steel with a hole saw but with a slow drill speed and some WD40 as cutting lube it's not that difficult.

Edited February 18 by blackrose

[magnetman]

It would be much better to just put another fitting in to match but always worth being a little reluctant. 

 

Someone mentioned the obvious answer earlier which was simply to route the second pump to the same bilge as the first pump. 

 

It doesn't seem like a lot of water should be getting in there anyway. It it is coming from above perhaps a cover of some sort over the deck or even over the engine might be considered. If a lot of rain gets in it will also probably get into the engine tray. 

[blackrose]

1 minute ago, magnetman said:

Someone mentioned the obvious answer earlier which was simply to route the second pump to the same bilge as the first pump. 

 

 

Yes he could do that if they are separate bilges. But then the boat effectively only has one pump taking water overboard. Anyway it's a better solution than T-ing hoses together.

[magnetman]

19 minutes ago, blackrose said:

 

Yes he could do that if they are separate bilges. But then the boat effectively only has one pump taking water overboard. Anyway it's a better solution than T-ing hoses together.

They must be separate bilges or the two pump question would not have arisen. 

It seems to me the amount of water being handled must be very small and also it seems to be likely to be clean water. 

 

 

The little Whale supersub pumps have removable joker valves / non return valves in the outlet. 

 

I think two of those would probably work via one hose. 

Edited February 18 by magnetman
unfathomable reason

[ditchcrawler]

5 hours ago, Tony Brooks said:

My thoughts also, but I would want to take care to site the fitting close to a rubbing band to protect it from the possibility of having the head knocked off in a lock. A hole saw in a drill with plenty of lube will do the job, even if it takes a while.

Been their and got the tee shirt, twice.

[Degobah Schooner]

Hello all, thanks for the suggestions! Great stuff! In review. 🤓

• Non return valves after each pump; not recommended by many, unless built into pump such as ‘Little Whale’ Supersub Pumps
• Pumps in circuit; second pump rerouted to pump out into first pumps reservoir which is then pumped out to waste outlet.
• Pump 1 & 2 pump out into a bucket containing a third pump going straight to the waste outlet. Advised to fit higher than the outlet, acting like a hopper tank, draining out by gravity.
• Cut/refit skin fitting for pump 2 on the opposing side.
• Expand the current skin fitting so there is room for pump two’s pipe alongside one’s original.

YES to mostly clean water coming in and not a lot of water in the bilge in the first place.

 

It’s not my boat so working to other's preference, which may need reviewing and adapting to, after all these options are mulled over.

 

I think I'm going to suggest a second skin fitting, being added to accommodate pump two as it’s own separate installation. It seems the most pragmatic and functional - in the long run.  Yet I do love the circuit option as a quick pragmatic fix for now.

 

Hypothetically and irrespective of the current problematic T situations, would a thinner pipe truly make no difference to how much fluid can travel up a pipe? - given that there would be less water being pumped and thus give the pump more power/capacity, which presumably would allow for a higher quantity of fluid to be pushed up. 🤔