One large automatic bilge pump. Or 2+ smaller ones?

[jeffsnox]

Is there any credence to the idea of fitting multiple smaller automatic bilge pumps rather than one larger one?

The Whale Orca 500GPH pumps are priced around £14 a piece... so it would be pretty cheap to buy 2 or even more and stick them all in place.

I guess for total redundancy you'd want an auto switch for each separately like...

Also not sure if you'd need a skin-fitting for each, or if it's feasible to plumb them in - meeting at a single outlet hose - without them fighting against each other somewhat.

Any thoughts?

 

[Bunny]

I have two auto bilge pumps fitted, and whilst messing about in the engine room I lifted one of the float switches to test and found it didnt work. Apparently float switches can just pack up, so personally i would go multiple, just in case.

 

[captainslarty]

We have 3 rule 3700 pumps in 3 compartment, 2 manual hendersons, 1 pond pump 12000 lph on 240v via sinewave inverter.
"normal" pump is small, self contained, rule 500 auto at the sump in the keel. this does the normal work. the only skin fitting is for the 500 and 1 of the manual hendersons.

the rest dump into the cockpit and out via the transom drains (2 * 3 inch tubes and 2 2 inch under drains)

in the vent of flooding, the cocpit is the place to dump if you have LARGE capacity drains.
the small pump is auto, as is one of the 3700s the rest are manual activation.

redundancy is ALWAYS better, float switches are unreliable, cheap pumps are not worth the money, each pump should have its own pipe and outlet.

and carry buckets

 

[pete]

Personally I would go for the multiple approach as already mentioned this provides a back up if one fails and on my boat water can lodge in different places.

For the outlet/s
I would have a large skin fitting above the water line
ideally on the transom with a large pipe rising up from it with the pump outlets rising up higher and then dropping down before connecting to the larger pipe creating there own swan necks to prevent water rising through one pumps pipework and returning down to another pump that is not running .
This will save you having to fit non return valves which often pass back and can block easily

Pete

 

[captainslarty]

Hi Pete, agrred, but only for the "working" pumps, if you CAN dump to cockpit, then you dont need the swan necks, this increases pump performance massively, you dont need one way valves either with cockpit dump. we intend, at some time, to fit the rubber flap lalves on the cockpit pump outlets, but never got a round tuit...

Joe

 

[ebbtide]

Obviously it depends on the layout of the boat AND what sort it is.
Wouldn't it be so much more helpful if we could just look that up in your Profile???

As my cockpit doesn't self-drain that's not where to chuck it.
Anticipate failure, blockage, whatever and duplicate everything, with at least one effective manual pump accessible without opening any lockers or hatches and turning any taps.
It helps if you can steer at the same time!

 

[boatmike]

________________-
and carry buckets
________________

Excellent!
Were you a boy scout by any chance?

 

[captainslarty]

[ QUOTE ]
Obviously it depends on the layout of the boat AND what sort it is.
Wouldn't it be so much more helpful if we could just look that up in your Profile???


[/ QUOTE ]

errr, its there, errr, in my profile.....

If YOUR centre cockpit thing doesnt drain well, then MAKE it drain well. if you cant be bothered looking at the profile, the she is an aft cokpit ketch (google seastream 34 if necessary)... the cockpit drains originally fitted (Designed before the very sensible 79 fastnet recommendations) were NOT up to purpose.. so we made 2 3" pipes from grp, cut holes, fitted pipes through transom.. on yours, you could lead them out the sidea, with a simple flap valve over the outlets.. one of the inherent problems with CC designs, apart from the height of the cockpit floor, increased moment arm. etc etc..

 

[captainslarty]

[ QUOTE ]
Obviously it depends on the layout of the boat AND what sort it is.
Wouldn't it be so much more helpful if we could just look that up in your Profile???

As my cockpit doesn't self-drain that's not where to chuck it.
Anticipate failure, blockage, whatever and duplicate everything, with at least one effective manual pump accessible without opening any lockers or hatches and turning any taps.
It helps if you can steer at the same time!

[/ QUOTE ]

I Just looked up YOUR "profile".... you have a stealth system... Jeeeeeeeeeeeeeeeez /forums/images/graemlins/laugh.gif

 

[2Tizwoz]

To add to a Lakesailoring it seems we now have a Malapropism. /forums/images/graemlins/laugh.gif

With a whole new meaning

 

[captainslarty]

or prioprism.............................................

 

[roly_voya]

A flaw in the multi pump theory nobody has metioned - small pumps loos far more performance due to resistance in the output line than big ones. This is largly because the surfice area of a small pipe compared to its volume is much larger, the same goes for the pump impellor. So yes multiple pumps for redundancy but consider anything with less than a 1.5" outlet a an automatic spunge for mopping up small spills not for coping with a leak. A good test is to remove the log impellor and see how your pumps cope, this coppies one of the most likely sinking scenarios which is the failure of a seacock but is also an exellent reality check!! I also regularly wash out the bilge by opening a seacock, keeps everthing sweet and chaecks the pmps at the same time.

 

[ADLS]

tried auto pump once but found having it trip in and out at night troublesome. Also they don't work well in a swell by the time they trip in the water has flowed away from the pump. I have 3 manual pumps now, 1 switched direct and 2 through float switches that can be lifted and held open, for testing and reducing water level below the swich shut off level and working in rough seas.
I prefer to dump all pumped water directly overboard.
I once had a wave over the stern and was glad the cockpit drains had only that water to deal with, the pumps took care of what went into the bilge. I was never more glad to get into Well's Next the Sea that night!!!!

Keep everything simple and stand alone.

 

[col_shaun]

my own feeling on this is one large pump on a float ond put the rest as and were you would need them as there could be a brake doun on the big pump and you will need the smaler ones in the place, as for cheep pumps not being worth there money, well a pump is better than know pump, also watch out for the older ruile floats as water can get in them and when it freeze up on a frosty knight the swich will break as there is mercery with in and the glass breaks.
the one pump that iv had after haveing the sinking feeling once was a small petral powerd one, and it got used as the drop keel came in throwe the keel box and flooded the cabin that pump was on that day and it saved the boat thank god.