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Old 13-01-2008, 16:43   #1
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2 x 2000 gph bilge pumps - reasonable?

I am currently considering the bilge pump system on Insatiable.


We don't currently have any electric bilge pumps (only the 2 x manula bilge pumps required for offshore racing back under IOR / IMS).

My current thinking is to get 2 x Rule 2000gph 12v bilge pumps, but rather than permanently fitting them, have themstored in a locker and connect them directly to the batteries if/when they are required. We are about to fit a 3rd battery, which will give us 2 x house, 1 x engine battery.

The question is, is 2 x 200gph bilge pumps reasonable / realistic? Obviously, more is better, but these suckers draw a lot of current, and battery power is finite. What do y'all reckon?
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Old 13-01-2008, 17:04   #2
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what is the cubic volume of your bilge space?
2x2000 could be too much.
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Old 13-01-2008, 17:30   #3
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The volume of the bilge space is tiny, but I'm not really talking about a system for keeping the bilge dry of incidental water... the occasional swab-out with a sponge and a basin will do that. I'm more talking about stopping the boat from sinking if, say, a sea-cock fitting broke- or if we put a hole in the boat (obviously, a decent size hole will probably sink the boat anyway, unless you can get it at least partially blocked quickly.

I'm talking about deploying these pumps in a situation where the floorboards are already floating, or close to it.
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Old 13-01-2008, 17:37   #4
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and the volume of your bilge plays into this.

If you have small bilges you need big bilge pumps. If your bilge is on the order of a crew cabin. Then you can step down to a smaller pump.
The reasoning is simple. A large bilge and hold more water and delay the time needed to dewater. A small bilge can't hold as much and needs to be dewatered quickly.
2000 is high and the amp draw will shut down a set of batteries quickly. Do you have an inboard engine?
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Old 13-01-2008, 17:55   #5
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I have an inboard engine; Its a volvo 29hp (M2003?).
The bilge space is, basically, almost non-existant - the boat is an old (1984) IOR "1-tonner" ex-racer, so the floor is, essentially, straight onto the spider.
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Old 13-01-2008, 18:00   #6
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ok, why don't you T your hose going into the raw water pump and put a pick up in the bilge. Then you can switch to internal sea water pick up and steam to port and clear the bilge. While charging batteries to run the 2000GPM pump.
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Old 13-01-2008, 21:23   #7
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ok, why don't you T your hose going into the raw water pump and put a pick up in the bilge. Then you can switch to internal sea water pick up and steam to port and clear the bilge. While charging batteries to run the 2000GPM pump.
I sort of had that plan, but more rough-n-ready; I planned to close the cooling water inlet ball valve and undo the hose clamp and let the water get sucked straight from te bilge, but really, I guess doing it "properly" is safer and allows for a strainer (to prevent bilge detritus from being sucked into the engine).
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Old 13-01-2008, 23:57   #8
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As the saying goes, "it depends on the size of hole you intend on making".
Pat has made some great points. Good plan to follow.
I would add one thought I had when reading. If you have a situation like you describe, trying to find the pump, connect it to power and connect it to plumbing woudl take valuable time you would not have. I suggest you do permanently mount the pump in situ. To aid in current draw, why not have a 1000 or even a 500 plus the 2000. You can switch between either or both depending on need. I am not sure I would worry much more about current draw than that I have just described. I see it as, if the situation is that bad, you don't care about if the batteries go flat, you want to remove water, find and fix leak. Then worry about the batteries. Or it maybe a case of, buy you as much time as possible in a emergency. If you have an engine to back up the pumps with charging, then you have no worries at all.
I am not so sure you want to play with cooling water inlets. Leave the engine in a trust worthy running condition. Make a mistake or foget and you cook up the impellor or worse the engine. And if that is maintaining charge, then fixing your water leak before the batteries become to weak becomes a major priority.
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Old 14-01-2008, 00:35   #9
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And consider the pumping rate of the engine water pump. Looking at the amount of water coming out of my boat's exhaust, it can't be very much. I agree, you really want to have something at least semi-permanently installed, and after that a backup system would be good.

Make sure that you have what is needed to give you a fighting chance at stopping the leak. It doesn't take much of a hole to overwhelm the typical electric bilge pump.

Regarding the Rule 2000 GPH, the specs say they draw 8.4A @ 12V, so any reasonable battery should run this for quite a while. But, 2000GPH is only 33 gallons/minute. By comparison the flow rate of a 2" hole only 6" below the surface is 55 GPM. And, the Rule 2000 pumping capacity is only 2000 GPH at 13.6V, and with no head. If it has to push the water up 6.7 ft, the output drops to 1160 GPH at 12V (if the pump actually meets the published specs).

I guess my point is that you probably shouldn't consider this an "emergency" pump! I realize that you already know this, but I figured it couldn't hurt to emphasize it.
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Old 14-01-2008, 02:02   #10
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Ask Kainui. He can move that quantity with a bucket. But he has to be worried at the time to be able to keep up.
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Old 14-01-2008, 14:02   #11
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And consider the pumping rate of the engine water pump. Looking at the amount of water coming out of my boat's exhaust, it can't be very much. I agree, you really want to have something at least semi-permanently installed, and after that a backup system would be good.

Make sure that you have what is needed to give you a fighting chance at stopping the leak. It doesn't take much of a hole to overwhelm the typical electric bilge pump.

Regarding the Rule 2000 GPH, the specs say they draw 8.4A @ 12V, so any reasonable battery should run this for quite a while. But, 2000GPH is only 33 gallons/minute. By comparison the flow rate of a 2" hole only 6" below the surface is 55 GPM. And, the Rule 2000 pumping capacity is only 2000 GPH at 13.6V, and with no head. If it has to push the water up 6.7 ft, the output drops to 1160 GPH at 12V (if the pump actually meets the published specs).

I guess my point is that you probably shouldn't consider this an "emergency" pump! I realize that you already know this, but I figured it couldn't hurt to emphasize it.
The above post pretty much gets to the crux of the matter; that being that it doesn't take much of a hole below the waterline to overwhelm any practical & realistic bilge pump system. Short of having a deisel or petrol motor driven pump, you are really just buying time to find and stop (or at least slow) the ingress of water before the boat sinks.

So, given that I have neither the money nor the inclination to buy a deisel or petrol motor driven pump, I have to arrive at a compromise that will provide some assistance, but which takes into account the reality of my boat, budget and battery bank (alliteration much?). I mean; sure, it would be great to have a 20,000 gph bilge pump system, but that is not realistic and it isn't going to happen.

Although I note the comments about the time required to connect stored pumps to the battery system, it was pointed out to me that this method does have the advantage that if things are getting really ugly, you can relocate your batteries to higher ground (i.e. the cockpit) before they get submerged and still run your bilge pumps....
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Old 14-01-2008, 20:06   #12
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Slight thread detour: Has anyone seen or installed one of these propshaft-driven impeller pumps?

They say "The smallest Fast Flow pump will pump 24,000 gallons/hour at 2,000 rpm".

It looks like a great concept, and it pumps over 10x the Rule 2000, but it's probably just one more good idea that I'll never get around to trying.
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Old 14-01-2008, 23:28   #13
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Err, that's 400GPm. That is a substantial amount of Hp to handle that flow rate. I do know of a boat that did somethign similar however. It was mounted off the front of the engine. The beauty of these Centrifugal pumps is that they can run endlessly dry. The will only pump once the water level covers the intake and floods the impellors. They will not suck if air is present. That means they won't suck up the very low level water, but they certainly will move a lot of water once the level gets high enough. Any of those pump types could be modified to be driven off the front of the engine.
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Old 15-01-2008, 00:15   #14
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Have you guys pondered a dedicated crash pump?

I'm considering finding a space for my 5 horse brigs powered pump. I think its a 250gpm model, but its been years since I mothballed it.

Without an inboard engine the thought of hand pumping a bilge on a sinking boat, particularly while single handing is not pleasant. Even with a one gallon per stroke diaphragm pump its limited to around 30 gallons a minute... but its hard to pump and patch at the same time.
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Old 23-01-2008, 05:34   #15
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I have 1 500 gph pump in the sump at the bottom of the bilge connected through an automatic float switch, then three 1,000 gph pumps with the float switches set at different heights in a reasonably deep bilge. These all run up to a manifold to join together before discharging via one outlet. The pumps can be left on in the auto position all the time as there is no energy consumed unless they are activated. This may seem like overkill but I sleep well when away from the boat not worrying about a burnt out pump motor allowing excess water to build up. I set this system up after reading a story about a centre cockpit yacht that almost sank after pamphlets were placed in the cockpit by well meaning chandlery's. It rained quite heavily and turned the pamphlets to mush which blocked the cockpit drains and allowed the water to build up enough and enter the cabin (it must have rained very hard). I don't envisage this happening to me but I do feel a little better knowing that there is at least some form of backup system in the event of electric pump failure whilst I'm not on board.
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