Crash Pump / emergency bilge pump

[jimL]

We have a 2001 Grand Banks Europa 52 that is new to us. We think the previous owner had installed a crash pump off the starboard engine. We’re familiar with crash pumps because our previous Mainship aft cabin trawler had one on each engine.

The theory is that if you are taking on water, more than your high capacity pump can handle, one goes to the engine room and turns the valve so the engine sucks the water out of the bilge instead of taking cooling water from outside the boat. I understand the concept.

What has me baffled is that when I sea-trialed the boat and subsequently moved it 90 nm the crash pump valve was open, but no water came in the boat (ok, makes a few drops). So this weekend as I inspected each seacock and valve I moved the valve to closed. I’m guessing the top part of the valve must be above the waterline otherwise I would have sunk a few months ago.

Please look at the pic of the closed yellow valve and render any thoughts. Is there a reason to keep the crash pump open during normal cruising – other than if something we terribly wrong, the engine would suck excessive water out?

Ideas?

Thanks

Jim

 

[rgano]

I'd need a system diagram pointing out where that valve is in the system to be able to come up with an idea for you.

 

[chriscritchett]

Go buy a lottery ticket?

I’d guess your theory is correct about being just high enough above WL. But still, if you’d ever gotten enough of a slug of water to start a siphon somehow…spooky.

 

[Taras]

have you followed the hose inside the boat to the "thru hull" to look for an elevated "loop" in the hose which should be well above the waterline to prevent water from coming in?

 

[tiltrider1]

Stop. Your logic makes no sense. Something is wrong and I would not operate the boat until you know for sure we’re all the handles should be. I need to see more pictures before I can tell you what you have.

If it is a crash pump and the valve was open all you would do is suck air and your engine would over heat.

 

[AlanT]

Stop. Your logic makes no sense. Something is wrong and I would not operate the boat until you know for sure we’re all the handles should be. I need to see more pictures before I can tell you what you have.

If it is a crash pump and the valve was open all you would do is suck air and your engine would over heat.

Agree. The hose leading from the crash pump would terminate in a bilge not a through hull. The concept is that is pulls water from the bilge when open instead of from the engine intake through-hull, circulates it through the engine to maintain engine cooling then exhausts it in the exhaust system. The engine would suck air if opened when there was not a flood situation in the bilge. Sucking air would cause an overheated engine.
~A

 

[Simi 60]

Pumping bilge water via raw water pump is not enough unless running at full noise
On our larger than many 855 Cummins at cruise speed our bilge pump is I would think, faster.
Specs say we need to be running at 1750rpm for 3500gph via raw water pump.
Our cruise is 1150rpm.

Better to have multiple electric and some more again imho

We have 3 X 3500gph at varying heights
Plus 2 additional 4500gph 240v trash pumps that can be bought on line at the flick of a switch

 

[gsholz]

To my surprise, our 1998 GB 52 Europa only had 2 electric bilge pumps and one manual pump from the factory. Coming from a 60' boat with 5 large bilge pumps plus a gas powered emergency pump, I thought this was inadequate. We added two 3/4 hp 120V sump pumps adding about 10,000 gal/h dewatering capability.

 

[sean9c]

Those things always scared me. What happens if you suck the bilge dry and end up with no cooling water for the engine? Or such a bunch of bilge crap into the engine water pump?

 

[HopCar]

As you said, the valves in the photos are closed. It looks like they are in the emergency pickup hose.

If I’m correct, in a flooding emergency you’ll want to open those valves and close the seacock. When the emergency is over you’ll want to open the seacock and close those valves before the pump sucks air.

If you ran 90nm with them open it should have damaged the pump impellers and caused the engine to over heat. Could those pickup hoses be blocked somehow?

It’s unlikely, but the stems in the valves may be broken and moving the handle may not move the balls. I have seen that happen but only once or twice in fifty years of selling valves.

Can you put enough water in the bilge to test the system?

 

[twistedtree]

I get the principal, but I think most of these setups are fundamentally flawed in practice.


If you have excessive flooding, as HopCar says you need to close the main thruhull for the sea strainer, then open the valve to draw from the bilge. But you need to man both valves the whole time. If the main thruhull is closed for more than a few seconds before you open the bilge valve, you can trash the seawater pump. Then you are double forked.


And when the engine drains the bilge and starts to draw air, you need to quickly get the main thruhull reopened and the bilge valve closed or you will again run the pump dry and be doubly forked.


So you need to open and close the two valves in concert, while monitoring the bilge level. Hopefully the two valve handles are in one place, reachable at the same time by one person. Otherwise you need two people to man it.


I think a big pump controlled off an existing or dedicated float switch is a much better way to go, and frees crew to focus on fixing the problem rather than operating bilge pumps.

 

[HopCar]

Twistedtree you don’t actually have to open and close the valves at the same time. You open the emergency pickup then close the seacock. Then when the flooding is controlled, you open the seacock and close the pickup. If you screw it up you might loose an impeller. If your boat is sinking, don’t worry about the engine. You can deal with that problem once you prevent the boat from sinking.

I would prefer a belt driven pump instead of using the cooling pump but this is a cheap and easy way to increase your pumping capacity.

I did install a similar system to the OP’s on my boat but luckily I never had to use it in anger. I did test it and it moved significant water.

The emergency pickup should be installed between the seacock and your raw water strainer. That way the strainer should catch anything in the bilge that you hadn’t vacuumed up the day before. You do vacuum your bilge every day don’t you??

 

[Bacchus]

Jim
I agree with others... something ain't right and needs to be investigated which is your point in asking.
Have you pulled the cover to your sea strainer to see if you get inflow with sea cock open?
Can you push a flexible snake up the emergency line to ensure it is open? Or just add some water to the open sea strainer to see if it runs out the E- hose?
Does the valve handle turn freely? And appear, at least to turn the stem / ball?
I do not have this set up but understand the principle involved. Constant tending is the problem in my mind.
I have thought about possibly adding a system like this on my Gen so I could run / shut down as needed and if something screwed up I didn't endanger my main (single) engine operation. Being yours is installed obviously important to figure out how it works.

 

[HopCar]

Groco actually makes a seacock and an adapter that are designed to allow you to use your engine raw water pump to empty your bilge in an emergency. It also makes it easy to flush your engine.
https://www.groco.net/products/valves-seacocks/flanged-valves/sbv-series

 

[High Wire]

Could there be a check valve on the emergency suction line down by its strainer? The water head on top the CV may hold the disc closed until the seacock is mostly closed. If there is, that's a smart design except check valves tend to stick (open or closed) in seawater use. You need to look at the end of that line.
If there is a check valve it needs to be inspected for proper operation.

 

[jimL]

Archie - I think you nailed it!

A check valve where the raw water strainer pick up - would also explain why I'm seeing a few drops a minute in the bilge where this hose empties into the bilge and why my bilge aways has a shallow amount of water.

That would also explain why, as the other posters have indicated, that my engine should have over heated by now, but didn't!

I will check this out this weekend, and now it all makes sense (I'm 2.5 hours from the boat)

Thanks all for your recommendations and suggestions. This fourm is invaluable. I'll let you know what I find.

JimL