Bilge pump mounting position

[Rupert Bear]

Silly question time but hey, the only silly ones are the ones you don't ask, right?
Rule bilge pumps, is there any reason why you can't mount them horizontally? the exit route for the pipe and various other things are easier in this orientation although I know that I won't get the sump quite empty I am not too bothered about that.
Just want to make sure that they are not designed to run in the remains of the bilge water and running it completely dry on its side will not bugger it up.

[limeydal]

Don't know why not! The literature says they are safe to run dry so shouldn't be a problem. Just a little more stress on the mounting bracket I would think as the weight is now flexing it instead of pushing right down. So bouncing around in a RIB might cause the bracket to fail.
I just fitted a rule 1100 with electronic level sensor to my XS-550.
However couldnt face drilling a large hole in the transom until I knew I had the right setup. So found the rule fitting married nicely to 1" solid PVC pipe.
So put a rule elbow right off the pump and then up an over the transom.On the other side of the transom I put another elbow downwards ;so prevents the pipe from moving.If I ever want to change the pump; the push fit rule elbow just slides off. No hose clips to unscrew!
Seems to work well so far!
cheers Dal

[Simon B]

RB,

We have a 4000gph monster fitted to our RIB (got it cheap and really shifts it) it tends to run dry as soon as air enters the pump through the grating. I think this is because that is the bottom of the impellor but havent tested it yet.

when it does this it entrains loads of air into the little remaining water left to pump, thus pumping it very inefficiently. With the pump on its side I would hazard a guess that it would start to do this as the water level reached the top of the grating and the pump then "sucks a vortex"

[Ian Austin]

Rupert
If you mount the bilge pump on it's side there is a very strong chance it could cause a vortex (pulling in air) which wold cause the impeller to cavatate and with a head of water it will not pump, the only way to get it to pump again it would have to be switched off to let the water in the pipe to return to the bilge, you do not have to use a stiff pipe to get rid of the bilge water, you could use a colapsable pipe there for it would find it's own route.
HTH

[Pete7]

Limeydal,

Why is there an elephants trunk inside the boat ?

Pete

[swginn]

I can answer that one for you. The elephants trunk is actually tapered and goes around the cables exiting an underdeck wiring loom and to above water level. This stops any water ingress to the under deck loom. The under deck loom is watertight anyway and does leave the hull completely void sealed. This is just there to prevent any water entering the underdeck loom and reaching the centre console (where the cables enter the loom). I guess it's a bit overkill as the water level would need to be very high in the boat for it to enter the console. I suppose overkill is the better solution when working on RIBs though.

[ashbypower]

Hi I think you'll find it's the
underdeck ducting outlet. However on the 550 I've seen it had a witchs hat.
I could be (and most probably am) wrong.


Brian

[limeydal]

Brian,
hope this clarifies things,
cheers Dal

[ashbypower]

Cheers Dal, I guessed it would be something like that. Unsure what arrangement our 550 is coming with, but certainly like the layout of your's Do let us know how she goes when Skeg is sorted and the Suzi is "Run in".


Brian

[lc0021]

Mmmm ... I notice from the photograph that the exit from pump is tight over the top of the transom and then exits below the level of the transom..

Is it not necessary to put a large U bend on it to stop water syphoning back when the exit is under water - say in the stern wave when slowing down ??