Bilge pumps...where to install

[Barrie]

If you had it to do all over again, where would you install 3 bilge pumps in a Tri cabin or Tri Fly. I’m assuming the hull is the same for both.

I’m thinking, one (750 gph) as far forward as possible before the hull starts to rise, just outside the forward head door in the “V” birth

And a second (750 gph) about 24” forward of the transom, between the engines as flat as possible to the hull and an additional one in the same location but raised about 2” from the hull (for those situations where a 750gph can’t manage).

I have a shower sump box that collects water from the shower, ac condenser and the footwell drain (Tri Fly) (1250 gph).

The sinks at both the heads and the galley drain from through hulls

There’s also a manual pump in the “V” birth locker
Thanks for your input.

[P-Dogg]

If I was starting from scratch, I'd look up the " dreaded hollow keel" thread and put one in there, prolly biased forward. Then it would be the only pump to ever turn on. Everything else would be a backup.

[P-Dogg]

High water alarm while you're at it?

Most folks have them way too high in my experience. I'm using goretex (effectively dripless) packing on everything. Most water I get I believe blows in through the vents. But of course it is good to plan for the unexpected. My boat sits bow low at rest, so the pump that is at the foot of the forward steps does almost all the pumping that is needed. Would be fun to put a cycle counter on the mid and aft pumps. My mid pump switch doubles as my alarm switch, because that pump never has a legitimate reason to run.

Recall that pumps are rated when supplied with 13.6 volts, not 12. And head losses add up quickly. Use good low-friction hose. I like the clear kind with external ribs, so that you can see what is happening.

[P-Dogg]

High water alarm while you're at it?

Most folks have them way too high in my experience. I'm using goretex (effectively dripless) packing on everything. Most water I get I believe blows in through the vents. But of course it is good to plan for the unexpected. My boat sits bow low at rest, so the pump that is at the foot of the forward steps does almost all the pumping that is needed. Would be fun to put a cycle counter on the mid and aft pumps. My mid pump switch doubles as my alarm switch, because that pump never has a legitimate reason to run.

Recall that pumps are rated when supplied with 13.6 volts, not 12. And head losses add up quickly. Use good low-friction hose. I like the clear kind with external ribs, so that you can see what is happening.

[comodave]

I think that I would go larger than 2 750gph pumps. The shower sump isn't really a bilge pump so I would not count it. Boat/US recommends 1600 to 2000 gph for 35 to 40' boats. I would stray to the larger end of the scale and bigger is always better in bilge pumps. Then size your wiring correctly and use smooth bore discharge hose. And then hope that you never need them...

[Barrie]

Great advice/info thanks. P-Dogg and comodave


I was thinking of the smaller pumps because they are more flush to the hull and would leave less water behind and they have a smaller discharge hose also leaving less water behind.

But, if I open the keel and place a pump in it, that would really drain it ....thanks P-Dogg. I will read the hollow keel post

[oil&water]

Well, the smaller bilge pump thinking may not be entirely true. Almost all bilge pump float switches start at 2" of water and stop at 3/4". Yes, you could run the pump until it is below the strainer level, but the water in the tube will still backflow to the bilge. The very best pump I have ever seen is the tall plastic hand pumps with the T handle and the corrugated hose. You can suck up almost all the water in the bilge with those pumps.

[RWS]

I upgraded the factory 3 to 1500 GPH each

added an additional higher mounted switch for a backup in the lowest part of the bilge at rest AND in the Engine room, BOTH running off the isolated genny battery.

Added bonus was adding crash pumps to the engines during the refit.

On top of all this, she sports the International bilge alarms IN ALL THREE BILGE COMPARTMENTS !!!!!

RWS

[WayWeGo]

Do any of you have a diaphragm pump in use? That seems like an interesting choice for the pump draining the lowest location in a boat, especially with GFO packing, since it would allow getting more of the water out of the bilge or keel and allow you to have a very dry bilge. The downside is cost and more complicated plumbing and electrical. And I would want a higher volume submersible pump as a backup.

A very nice bilge pump switch I ran across is the Ultra Safety Systems: http://www.tefgel.com/contain.php?param ... itch_price. The senior model has a high water sensor built into the same package. Of all the switches out there, this one seems to have the best reputation on large yachts and commercial applications.

[WayWeGo]

Well, the smaller bilge pump thinking may not be entirely true. Almost all bilge pump float switches start at 2" of water and stop at 3/4". Yes, you could run the pump until it is below the strainer level, but the water in the tube will still backflow to the bilge. The very best pump I have ever seen is the tall plastic hand pumps with the T handle and the corrugated hose. You can suck up almost all the water in the bilge with those pumps.

A diaphragm pump can take care of most of these issues. It is mounted above the bilge, usually in a closet or cabinet, and draws the bilge water through a strainer in the bilge and up a hose to the pump. They are self priming and use check balls to avoid the water flowing back into the bilge. Since this is not the most reliable setup, you should have a submersible backup in case the diaphragm pump's strainer gets clogged or the check balls are dirty. Often, diaphragm pumps are only activated by a manual switch when you want to get the bilge really dry.

One advantage for our boats is that if you have a keel filed up with water, you only need to drill a small hole into the keel because the pump can be mounted above.

[BobCT]

If you have relatively easy access, one way is to use your shower as a shop vac. What I did was, add!a T and some shut off valves then ran a 1/2" hose to my engine room. There, I have a screen filter and about a foot of hose. When I want to vaccuum up the standing water, I just flip on the shower drain switch.

For the few times a year I need the shower drain to work, I just turn off two valves to disable the part I added. On my boat, the engine room is the only place I get standing water when it rains so I have it pretty easy. I agree, go bigger on the pumps, 750gph is a dribble once you factor in voltage and hose head. I have three 2,000's and a 4,000 on mine.


Bob

[Barrie]

Ok, great info,

High water alarm
Clear external rib/smooth bore hose
Bigger pumps 1500 gph plus, with sufficient gauge wire for ampere draw
Investigate “hollow keel” and ideally install diaphragm type pump and strainer
Lots of great ideas, thanks a bunch

Now how about switches
Built in automatic or the external float. Is one more trouble free/reliable than the other

[WayWeGo]

Now how about switches
Built in automatic or the external float. Is one more trouble free/reliable than the other

The one that I kept coming back to for reliability was: http://www.tefgel.com/contain.php?param ... itch_price. You can sometimes find better prices for it from industrial suppliers than marine ones.

It us used in many $$$ boats and also in commercial/industrial applications.

[Barrie]

I looked at those in your previous link. I assume that's the "switch" on the left side
Not really that much more money for something that's going to get the job done

I'm going to check locally (Ontario) and see if I can find a dealer or supplier for them

Thanks WayWeGo.

[WayWeGo]

Yes, the clear plastic tube next to the pump is the switch. I bought mine from Corrosion and Marine Solutions: http://corrosionandmarine.com/store.html