Bilge Pump Non-Return Valve

[sea1ljs]

Ok let's add a question from left field. Emergency gas driven bilge pumps are used by the Coast Guard and sounds like a good defense for emergency de-watering. The problem with that solution is the practicality of storing one onboard not to mention keeping a supply of “fresh” fuel onboard. There’s the suggestion of a two way valve on the boat’s engine water pump">raw water pump as an emergency pump but what if you forget to switch the valve when the bilge runs dry? I’ve considered installing a vane pump on my 1 cylinder Kabota diesel engine I use to drive my alternator for power generation but it’s amazing how much even a small pump costs. So here’s the question from left field; what about an electric sump pump used in domestic water wells? They’re made to deal with high volume of water movement and head pressure. Yes there’s the question of electrical power should the batteries becomes submerged but I weigh that against the maintenance required to keep a gas pump viable. Fire away.

[Cheechako]

I see Whale has a new line of linear design bilge pumps now that have built in check valves. They are longer but small diameter. A thought occurred to me the other day when I had to have a new pump installed in my well. If you have a gen set, a well pump would be really good. They are 1/3 hp and larger. 4" diameter, stainless steel. My 1/2 hp model easily pumps 200+ foot head! The water spews out of a 1" pipe like a gusher! Not cheap, but not that bad in terms of a boat buck! it's a linear design so would have to lay on it's side in the bilge.... Mine lasted 14 years with daily use and lots of grit in the water....

[sea1ljs]

Cheechako

Are you refering to a bait well pump?

I just reread your post and I'll assume you're referring to a domestic well pump. I see these at Home Depot but keeping in mind we're talking marine use here. I'm just wondering what the downside may be.

[Cheechako]

No, an actual in the ground landlubber well pump like this for instance. (no relation)
Goulds Water Well Submersible Pump 18SB10412C 18GPM 1 Hp Goulds Submersible Pump on eBay!

[sea1ljs]

So theoretically this pump would pump 1080 gallons an hour. Sounds impressive but I would imagine a larger capacity pump would be in order but it’s certainly a start. Any brainiac out there with answer of how many gallons per minute a 40,000lb boat would encounter with a small 1 inch hole (failed through hull) 2 inch, 3 inch, etc. I’m sure there’s a table somewhere. And don’t forget the soft plugs after you find the failed through hull.

[roverhi]

The problem with the CG pumps is they either don't start or can't be recovered onto the boat. Don't know how many times it's reported that the CG dropped a pump to no avail.

I've got my trusty Edson in the cockpit locker. That sucker will move a lot of water relatively easily. Still, any pump will have a very hard time keeping up with a hole larger than an inch or so.

[cal40john]

Originally Posted by sea1ljs

So theoretically this pump would pump 1080 gallons an hour. Sounds impressive but I would imagine a larger capacity pump would be in order but it’s certainly a start. Any brainiac out there with answer of how many gallons per minute a 40,000lb boat would encounter with a small 1 inch hole (failed through hull) 2 inch, 3 inch, etc. I’m sure there’s a table somewhere. And don’t forget the soft plugs after you find the failed through hull.

18 GPM isn't a lot if we're talking disaster pumps like the coast guard drops on you. A Rule 3500 is 58 GPM theoretical, even if you rate its true capacity at 1/2 that to account for head, hose run and low voltage you're still at about 30 GPM. Draws 15 amps at 12 volts.

Here's a thread I started long ago asking about more in the 100 GPM pump sizes and it has a discussion on flow rates through holes:
http://www.cruisersforum.com/forums/...read-6547.html

[sea1ljs]

Thanks for the thread link, very informative.

[HopCar]

What do you guys think of this pump? Does it have a place on a boat?
I think it sells for around $200. D Best Pump Ltd. | Manufacturer of The Crank EZ Pump

[Cheechako]

I've never seen a Rule pump, even the 2500 GPH actually put out water the way these well pumps do. I think they must rate the Rules by testing them in zero gravity! :>) At any rate , it's a wild idea! 18 gpm is almost twenty 55 gallon drums an hour if you think of it that way. But realistically, I think only a trash pump is going to keep up with a severed 1.5 dia hose. and likely nothing is going to keep up with an underwater hull crack.... Seems like if you have a big boat and a gen set, having a big 120v(?) trash pump, or one mounted on the gen motor!, would be a good safety thing.... although beyond what I would ever do!

[sea1ljs]

My basic thinking of using a high capacity pump is to buy some time while trying to sort out a possible failed fitting or whatever is the problem. Beyond that it would merely be a helpful tool delaying the inevitable while grabbing the ditch bag and deploying the life raft. Even then, as past cases have shown, it may not help at all because events are happening too fast such as a major hull breach. The fact is if it doesn't require a lot of space to store, isn't too expensive, low maintenance and easy to deploy chances are you may want to have it on board to use when needed. After all what's the downside?

Collision mats.... now there's another subject that could be discussed particularly now there is all that junk headed to the west coast from the Japan tragedy. Already items are being found on the Pacific NW beaches well ahead of predictions.

Thanks to all for the links and info.

[risailor]

I have had the same problem, which continued even after I raised the float switch. What I finally did was install a circuit to keep the bilge pump operating for an additional 15 seconds. This provide additional time for the pump to clear the discharge line.

In case you are interested, I have attached a photo. I picked up the timer circuit at Amazon for $16. I added an automotive relay to control the pump, versus using the onboard relay of the circuit.

Happy to help with any questions.

[GordMay]

Greetings and welcome aboard the CF, risailor.

[Cheechako]

Originally Posted by risailor

I have had the same problem, which continued even after I raised the float switch. What I finally did was install a circuit to keep the bilge pump operating for an additional 15 seconds. This provide additional time for the pump to clear the discharge line.

In case you are interested, I have attached a photo. I picked up the timer circuit at Amazon for $16. I added an automotive relay to control the pump, versus using the onboard relay of the circuit.

Happy to help with any questions.

Not sure I understand this? The problem isn't the pump running long enough, it's that once the bilge is dry, the pump is trying to pump air, so it cant push out what water's in the hose. Once the pump stops, the water returns to the bilge. How are you making your pump push air?

[Kelkara]

Originally Posted by Cheechako

Not sure I understand this? The problem isn't the pump running long enough, it's that once the bilge is dry, the pump is trying to pump air, so it cant push out what water's in the hose. Once the pump stops, the water returns to the bilge. How are you making your pump push air?

I think that timer is a great idea, and I'm going to look into it.

How does it work? It works because the switch turns off before the bilge is actually dry, according to Rule my switch will leave 3/4 of an inch of water behind and the flow-back will add to that ... in my bilge this water is enough to slosh around in a swell tripping the switch, but not for long enough to pump out any water. By holding the switch in "manual" for 30 seconds longer I can clear the bilge of this water, and a swell won't cause the pump to cycle.