Auto Bilge Pump Plumbing

[cpedw]

Having just bought a Westerly Falcon, please prepare for a deluge of questions about getting it well prepared.

The boat currently has a single manual bilge pump. I am planning to install an automatic electric bilge pump as well.
Is this a good idea?
Would it be acceptable to T the new discharge into the existing manual discharge so saving on a new hole in the side?
If so, should it incorporate any extra fittings such as non-return valves?

Thanks in anticipation of your collective wisdom,

Derek

 

[gtmoore]

Hi

I had to do the same thing when I bought my boat but opted to run a new pipe. The main reason was the manual diaphragm pump had a very large pipe (38mm?) and the only submersible pumps that would fit my shallow bilge required 19mm hose.

It's probably not a bad thing to have a bit of redundancy but cutting the hole in the transom required a few deep breaths!!

Gavin

 

[Guest]

All bilge pump installations are good idea to have simple non-return - the pump if a Henderson etc. has a rudimentary one already - but is not to be relied on.

I Tee'd near the actual final outlet on one boat .... where it was good height above W/Line. On another boat where the discharge was at the w/line - I had the discharge into the self draining cockpit ..... as I played safe and always closed the overboard valve on the discharge through hull.

There is nothing to stop a short length of hose over the side from the pump without fancy plumbing etc.

Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[pvb]

New hole would be better...

If you plumb the electric pump to a new skin fitting, it will eliminate the need for non-return valves (which I don't think are a good idea in bilge pump piping) and ensure that both pumps can be used together with no performance compromises. Remember to loop new pipe up as high as possible to prevent siphon effect when heeled.

 

[oldsaltoz]

G'day Derek,

If you have the space, put a loop above the outlet for both pumps and 'T' them together at the fitting.

No valves required and no back flow into the other pump.

Hope this helps. . . . . . .

Soavagoodweekend Old Salt Oz /forums/images/icons/cool.gif

 

[Guest]

Nikagda ......

----- need for non-return valves ..... I advocate NR valves ..not to stop flow through the OTHER pump but to stop backfilling if anything fails / boat is heeled / boat gets waterlogged and outlet goes below water etc.

I certainly do not rec'd the cutting of MORE holes in a boat !! The size of the oputlet pipe existing may be big .... no problem as the electric pump can still be plumbed into it by using reduction fittings etc.

Still I reckon the best is to a cockpit self draining !!!

Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[pvb]

OK, that\'s another view...

But I still prefer to avoid non-return valves in bilge pump pipework, because of possible clogging problems. As far as backfilling is concerned, a decent high loop will prevent this in nearly all circumstances.

 

[Guest]

Re: OK, that\'s another view...

Agreed but then you inrease the pump head and we are talking an electric jobbie here ... not a manual positive displacement job etc. which will overcome quite a height !

The Falcon has a self draining cockpit and nice drains in the corners ..... why plumb at all ????

Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[tr7v8]

It's a condition of my insurance that I have an AUTO bilge pump on the boat.
I've brought a Rule 1100 auto (off of E Bay at a good price) that doesn't need a switch and intend taking it straight to the battery via a waterproof fuse. After a huge amount of reading I decided not to use a 1 way valve as one of the tests I read (PBO I think) said that it drops the throughput by about 5 %, as did a long elbow above the pump. So if yo do both you've just reduced output by 10%.
Another big output reducer was thin and long leads, so mine'll be in 2.5mm!

Jim
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[Guest]

Rule 1100 auto ...

1100 gph (open flow)
5 amps draw
Outlet 30mm

1100 less about 50% for rise and pipework = 550 gph

less 5% for non-return valve = 522.5 gph

Would you really notice the drop off for the valve ? I think it a good trade for safety ?

On a boat previous my auto was a Rule 300 std + s/hand auto switch from the Hamble barge .... about 20 quid all in .... I wanted the all in one 300 ... but the bilge space was not wide enough to accommodate - so needed to have separate.

I wired all together with an over-ride switch and then encased the joints in a small plastic box filled with epoxy - as the leads from the pump were quite short and I was worried about shorting the connections in the bilge. The box was then epoxied to the bilge side.

The pump albeit very small in capacity never had to run more than a few minutes ..... excellent and its output was into the cockpit to rain out via the outboard hole ..... before the outboard I cut - I had it to the manual pump o/board with a Tee and a non-return. The non-return was unnecessary in the cockpit output version !

Cheers


Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[tr7v8]

Re: Rule 1100 auto ...

Nigel,

I'll try and turn out the test but Rule 1100GPH and most of it's peers only managed about 50ish% of their rated output so
550GPH - 10% = 495ish GPH. That's before the volts have dropped a bit and the drag of the outlet and pipework.
I've already got a similar size pump and a manual, but I've also got 2 x Volvo's pumping vast amounts of seawater to stay cool and with relatively fragile rubber exhaust hoses. I feel I need all the help I can get in the event of failure!

Incidentally the footprint of this is the same as the standard one, it switches itself off every 2 1/2 minutes for a second or so, if it detects a load on the impeller it runs until the load is back to normal. It will then run for a further 30seconds and turn itself off, back into 2 1/2 minute mode. Twas only £ 40 or so.

Jim
------

 

[Guest]

Re: Rule 1100 auto ...

That agrees with my figures ..... the Specs are straight off their advertised blurb ..... so you should find it all tallies with what I wrote.

Believe me 40 quid for a Rule 1100 auto is good .... they were advertised at over 70 .....

My post was to illustrate the reduction in output, the ampage needed to operate and the use. My little 300 did a fantastic job where I had been advised by others to fit much bigger !! As the bilge stayed basically dry - because the pump operated at about 2-3 cms of water, the bigger capacity was unnecessary.

With your quoted lumps and potential ..... what about two of 'em !!!!!

Cheers


Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !