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Old 30-10-2012, 13:52   #1
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How Many Bilge Pumps ?

I am concerned that my new 42' boat is a little light in the bilge pump area. The deepest part of the bilge is in the engine compartment which has a manual whale pump. It seems quite efficient for a manual pump. There is also an electric pump in the middle of the boat where the pick up would be 50mm above the manual pick up in the engine bay. There is also a Y valve on the raw water intake where I can open it to the bilge and close off the raw water intake and let the 75hp Yanmar pump it all out. I would have thought that I should have at least 2 and maybe 3 electric pumps as the flow rate is not going to stem any significant breach. What sort of pumping capacity are boats this size normally delivered with?
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Old 30-10-2012, 14:01   #2
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Re: How many bilge pumps ?

How many watertight compartments does your boat have? There is some discussion on other threads about bilge pumps that you might want to have a look out. It's good to have a human powered, engine/mechanical and electrical pump. I think that's the best you can do within reason.

It's good to have backup pumps like you do but there reaches a point where the hole is so large that no amount of pumps are going to handle the flooding, and that is difficult to predict. Go with what makes economic sense to you realizing that there is no perfect solution that will handle all flooding situations.
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Old 30-10-2012, 14:25   #3
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Re: How many bilge pumps ?

On our boat (huge, deep bilge), we have:

- water witch (thanks to cruisersforum.com for the tip).
- electric hooked up to the water witch
- whale manual
- edson 1 gallon/stroke portable manual. thing is a beast.

Electric does most everything, whale manual backs that up. The big Edson is for dewatering other boats or our boat if there was some major problem. The hoses for the Edson are loose.
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Old 30-10-2012, 14:38   #4
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Re: How many bilge pumps ?

Having had 2 automatic pumps fail over the years I now have 3 set at different levels ..... maybe I'm being a bit anal but I figure if the first fails I still have the second and if that fails ... blah, blah, blah, .... anyway like I said perhaps I'm a bit anal.
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Old 30-10-2012, 14:42   #5
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Re: How many bilge pumps ?

Since my boat was an old race boat it had the required pumps for offshore racing. 2 manual pumps, one pumped in the cabin, one pumped on deck. One is a Titan 28 GPM, the other a Whale Henderson 18 GPM.

There was also a 6 GPM diaphragm electric pump to dry the keel.

I added a Rule 2000 (20-30 GPM depending on how much you derate it) up high in the keel with a float switch. Since I don't race this boat, I'm usually short handed and don't want to be stuck pumping when I should be fixing the hole.

If I ever get to go distance cruising (the whole point of buying my own boat and no longer sponging off of my friends), I'll add a disaster pump as being discussed in the other thread. Don't know which one yet.

John
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Old 30-10-2012, 14:42   #6
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Re: How many bilge pumps ?

I have one deep area within my bilge that would recieve water from any area of my 41' boat with three separate pick-up hoses at the deep point. One is a Whale Gusher manual, one is a Rule centrifugal electric pump and a third is a Jabsco electric diaphragm pump. I would have the option of picking up water with my Yanmar or Kubota diesel raw water intakes, but this would take some prep time. They are not "stand by" ready for use. My arrangement matches my acceptance of reasonable risk. One could always have more and always have an event that is overwhelming.
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Old 30-10-2012, 15:14   #7
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Re: How many bilge pumps ?

I think the engine pumps are more trouble than help. The pumping capacity of a Yanmar cooling system is less than a small bilge pump -- and I wouldn't want to risk overheating my engine when it sucks up a piece of of bilge trash right in the middle of an emergency.

Easiest upgrade is to install something like a Rule 3700 pump on a bracket clear of normal bilge water. Hopefully the thing will never get wet. The challenge is installing a thru-hull for the 1 1/2" hose but you will move a lot of water.

+1 on the Edson manual pump. No other manual pump comes close but it's very expensive.

Carl
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Old 30-10-2012, 15:33   #8
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Re: How many bilge pumps ?

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Originally Posted by CarlF View Post
I think the engine pumps are more trouble than help. The pumping capacity of a Yanmar cooling system is less than a small bilge pump -- and I wouldn't want to risk overheating my engine when it sucks up a piece of of bilge trash right in the middle of an emergency.

Easiest upgrade is to install something like a Rule 3700 pump on a bracket clear of normal bilge water. Hopefully the thing will never get wet. The challenge is installing a thru-hull for the 1 1/2" hose but you will move a lot of water.

+1 on the Edson manual pump. No other manual pump comes close but it's very expensive.

Carl
I agree about the engine pickup.
You should have one electric as big as you can fit in there. You dont want to be trying to use the manual whale while you are trying to manage a boat foundering in huge seas.... at least not until absolutely necessary....
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Old 30-10-2012, 15:46   #9
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Re: How many bilge pumps ?

As noted earlier, the racing rules used to call for two manual bilge pumps - one at the helm, and one below. (I don't know the current standards.) I consider these for emergency use only, and of less utility for a single-hander like me than for a crewed race boat. Nonetheless, I have both pumps (Whale).

Additionally, it is normal to have an electric bilge pump with an automatic switch for removing the small amount of water that works its way in via the stuffing box, condensation, small deck leaks, etc. Often these have too little capacity to be of any use for a serious leak, as with a ruptured hose. I think the electric diaphragm pumps are particularly undersized. I have used a Rule centrifugal pump (1" hose) which has worked well, but wasn't enough to deal with large leaks. I will be changing to a 1-1/2" 4000gph centrifugal pump during the current refit. This will provide enough capacity for most emergencies. This would allow me to concentrate on fixing the problem without dealing with an emergency pump.

I have always carried in a bucket a large centrifugal pump with a long 2" hose and a quick connector for electrical power. If needed I can drop it in the bilge, run the hose out the 4" port through the cockpit, and plug in to a panel-mount connector. I also keep an adapter pigtail with large alligator clamps to attach directly to a battery, if needed to help out another boat. As with other safety gear, I have never used this. My current thinking is that I was relying too much on this, as the permanently mounted pump was not all that large. Even though it would be very fast to deploy, that is still time which could be better spent stemming the inflow. Hence the change to the main pump noted above. Once that is accomplished, I may decide to sell this pump. Still thinking on it...

As with all safety gear, your choice of pump arrangements needs to be part of an overall strategy which will fit your boat and crew. Personally I don't see manual pumps as a great solution for a short-handed boat, but still very useful in the event that the electric pump(s) don't work, or as additional capacity. For me, there needs to be a high-capacity electric pump which will be quickly available, preferably automatically but possibly with a manual switch, or at least available to quickly plug in. Finally, an electric bilge pump of at least moderate capacity with an automatic switch is needed for everyday use. YMMV

'Hope this helps.

Greg
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Old 30-10-2012, 15:54   #10
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Re: How many bilge pumps ?

"I think the engine pumps are more trouble than help." (CarlF)

I'm inclined to agree, in the case of the cooling pump, but how about an extra engine-driven pump purely for disaster "de-watering" (not previously in my nautical vocab!)

Either belt-driven or in-line via a muff coupling from the crank or camshaft, or - for propshafts low in the hull, there used to be (ten years ago, may still be available) a very high-throughput option which was the ultimate solution for any diesel installation with a well engineered air intake:
I think it was axial flow, like a really crude waterjet unit, all cast metal, quite sizeable, with a split impeller which could be bolted around the shaft, and a split housing (with plenty of clearance on the tips of the impeller)

It didn't need an inlet; water just flowed into it at the suction end, IIRC.

(Maybe that's something like the "Waterwitch" referred to by rebel above?)

ON EDIT
Used to be made by Ericson (sp?)
Now by these guys:
http://www.yachtwork.com/bilge-pump.htm

Something like this would have saved the Bounty, I reckon. A few hundred horsepower can shift an awful lot of water.

(When I first heard the news, it occurred to me that manual pumps, much less efficient than the Edson referred to above, were sufficient to keep the original Bounty afloat during several months of trying to battle the wrong way around Cape Horn during the wrong season against conditions which would surely have sunk the replica....

but then I realised that was probably an uncharitable thought, considering how many people were available to man the pumps on the original. And they were not perhaps the happiest of possums thereafter.... )

It seems to me axiomatic that electric pumps cannot be included in any list of disaster-dewatering assets, but engine driven pumps (given a carefully thought-through snorkel, connected also to all breathers) will run indefinitely with the engine completely submerged.

If there is a smaller diesel, say for genset duties, this should be the one with the engine driven pump if the larger diesel cannot be started without electricity.

(I've done several trips on a 78' yacht with a 6LXB Gardner, which could be started by human power. The galley was designed with removable partitions, and the handles from one of the grinder installations detatched and brought below. Four big boys could kneel on the floor in the galley and get her up to speed for one cylinder to fire, the other five being decompressed. The flywheel was then heavy enough to allow bringing the remaining cylinders 'on-line' one at a time.)

Hydraulically (oil-)driven waterpumps are available, but have no relevance to the OP's question. Even if electric pumps are unconditionally submersible, it's hard to ensure that any battery bank, contactors, isolating switches etc will all survive

They clearly represent overkill for anyone likely to read this, except perhaps on very large vessels with multiple watertight spaces distant from the engine.
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Old 30-10-2012, 16:10   #11
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Re: How many bilge pumps ?

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Something like this would have saved the Bounty, I reckon. A few hundred horsepower can shift an awful lot of water.
Except the Bounty lost engine and generator power. Hence it lost the power to de-water the ship.
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Old 30-10-2012, 16:56   #12
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Re: How many bilge pumps ?

My last post was misleading: the Ericson / Fast Flow pumps are centrifugal, not axial flow.
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Old 30-10-2012, 17:07   #13
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Re: How many bilge pumps ?

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Except the Bounty lost engine and generator power. Hence it lost the power to de-water the ship.
I'm thinking that the most likely reason for losing both engines was electrical, so it's not so much a case of the electrics AND the engines, but the electrics HENCE the engines being down.

Even a ship that size should (to my way of thinking) be able to START, and certainly run, at least an auxiliary engine without electrical power, despite that engine's compartment being entirely full of water.

There are various well-proven solutions: A hand-started diesel donkey engine ("starter motor" engine, as "Cat" earthmoving machinery and graders formerly had); a hydraulic starter motor (with an accumulator, pumped up by hand), one or more cylinders rigged for pneumatic starting, etc etc...

Naturally it will require some finesse to design and install, or alternatively scuba tanks ..... if you literally want to be able to do it with the compartment full of water.

In our size range: a biggish diesel can be started (if you had the foresight to get a suitable capstan-style pulley machined for the crankshaft) by gybing or using a drogue line.

Especially if cylinders can be selectively decompressed.

I'm not casting aspersions here, just trying to learn lessons from the hard experiences and travails of others*, in whose place I might just as well have been
(*the easy way, my favourite)
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Old 30-10-2012, 17:26   #14
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Re: How many bilge pumps ?

There's good cause to consider preparation for stopping the inflow of water as well as pumping it out. Wood plugs, collision mats, creative use of uphostered foam, etc. In an emergency both sides of the flow require some good problem solving techniques.
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Old 30-10-2012, 17:29   #15
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Re: How many bilge pumps ?

My previous engine (Sabb) could be hand-cranked and required no electricity to operate. I had considered adding a belt-driven pump for emergencies; it used to be possible to buy such a pump with an integral clutch operated by a lever. That would have provided a powerful pump independent of electricity, until the engine was nearly fully submerged. Perhaps a bit of overkill - it never rose high enough on the list to get done - but a sensible alternative.

With the new engine it will be impossible to start or operate without electricity (that's an improvement?). So if there is electricity and the engine (with alternator) works, an electric pump is a good solution. If the engine/alternator doesn't work then at least the pump will run for a while off the batteries. If there is no electricity then there will only be manual pumps. The only advantage to a belted pump would be for the case that there is electricity for starting and the engine runs but the alternator fails - not too likely I think.

In the years out cruising I never completely lost the electrical system. Once I lost an alternator. So I am betting that it will be available in an emergency - or I'll have to man the pump handle.

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