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Old 06-04-2013, 18:46   #31
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Re: What do you all think of engine-driven bilge pumps?

And on hand-pumps:

An Edson double acting, gallon-a-stroke hand operated pump can operate at 30gpm indefinitely.

A moderately fit crewmember, provided they've got access to energy food, can easily keep this up indefinitely at a 30% duty cycle, and I would guess at a pinch keep it up for maybe twelve hours at a 70% duty cycle, possibly more.

As a consolation, it's far more efficient than the hand pumps in the original Bounty, which kept it afloat while they tried unsuccessfully for months to sail against the westerlies around Cape Horn, eventually taking the 'long way round'.
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Old 06-04-2013, 18:52   #32
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Re: What do you all think of engine-driven bilge pumps?

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My understanding is that the only high capacity pump on Bounty was a mains electric (ie AC) pump, which relied on a genset.
I know more than I ever wanted to about the Bounty . . . There's a ton of mis-information floating around about it . . . .

They in fact had 5 significant pumps on board, all in the 'major damage control dewatering' capacity.

Two were electric (AC). These seem to have not been working to their rated capacity, possibly with seal or impellor damage.

Two were hydraulic, driven from a PTO on the starboard engine. One of these was fixed mounted, and the other was semi-portable. They could only run one at a time. These had apparently not been used in quite some time and the hydraulic connections were all corroded, and we expect the insides of the pumps were also.

One was a gas powered 'portable' trash pump. They were required to buy this by MCA in England. They use it once (to show to MCA) and then never used it again. They could not get it working at all (the engine worked but the pump did not pump).

If all these pumps had in fact been in working order, they might well have survived, at least long enough to get to a shallow dock where they could rest the keel, because the combined capacity is absolutely huge. Before the replanking they apparently once were leaking 30,000gals/hr and the pumps kept up with it.
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Old 06-04-2013, 18:58   #33
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Re: What do you all think of engine-driven bilge pumps?

Andrew,
Maybe but these pumps have very simple valves and seals. As such need maintenance and cant handle trash. Agree that a good hand pump is nice but its no way to stem off a major in flow. The bounty went down because inflow exceeded the capcity to pump the water out. The strainers were reported to be clogging with debris. more to the point they had equipment but it could not handle the in flow. Maintenance etc.. but they did not work like they did when specked. I run a facility and test run the sumps weekly. How often had the pumps been tested on the Bounty? Why are the coast guard reports suggesting they clogged?
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Old 06-04-2013, 19:01   #34
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Re: What do you all think of engine-driven bilge pumps?

Evans

Thanks for that. Very interesting. I guess my source was reporting the pump(s) which were (marginally) functional, rather than those which were eye candy ... and not very appetising candy, by your account.

It's sobering, to those relying on a portable trash pump, that a brand new pump, which had demonstrably worked, did not work when needed.]

It's also a fair question why, with their evident reliance on pumps, there was not a direct-coupled engine-driven pump on either or both propulsion engines. In view of the inadequate maintenance, it would have helped if at least one had been a centrifugal pump with macerating rotor and ample internal clearances discharging above any conceivable waterline (so no valves required, and virtually immune to maintenance issues)

If fitted between engine and gearbox, it could be run at full output without requiring the vessel to make way.
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Old 06-04-2013, 19:08   #35
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Re: What do you all think of engine-driven bilge pumps?

Getting good suction/priming a trash pump requires training. They can be hard to prime. If you have ever used one you know it takes time patience bad words and a hammer sometimes
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Old 06-04-2013, 19:36   #36
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Re: What do you all think of engine-driven bilge pumps?

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Originally Posted by estarzinger View Post
Re flow rate with 'typical head', I usually figure half the zero head output.

Just for example . . . for one of the rule pumps, its 30GPM at zero head (which is the marketing flow rate), 21GPM for 5' of head, and 12GPM for 10' of head. And I figure the best practice anti-syphon installation has 6" or so of head.
I was thinking that the flow rate should be fairly linear between maximum GPM @ zero head, and 0 GPM @ maximum head. For example, the Honda WX15 specs a max flow of 72 GPM, and a max head of 125 ft. My prediction of flow for a lift of 8 ft would be 72 * (1 - (8 / 125)) = 67 GPM. Factor in a frictional resistance due to hoses and fittings, and we would see somewhat less.

It is interesting that the Rule spec you mention isn't quite linear with head.

In any case, with a max head of 125 ft for the small Honda, we shouldn't lose much flow in a typical boat application.
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Old 06-04-2013, 20:08   #37
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Re: What do you all think of engine-driven bilge pumps?

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Getting good suction/priming a trash pump requires training. They can be hard to prime. If you have ever used one you know it takes time patience bad words and a hammer sometimes

Take it from someone who worked on a daily basis with the best trash pumps money can buy, don't waste the space on the boat or the money. Even the very best, when fairly new, and when used every day, will start easily sometimes (50%) and prime first try about the same (50%).

When it is not used every day the numbers drop dramatically, not much of a last resort. At best, if everything goes right, it takes a few minutes to set up and prime, and you need something NOW.

I really like my Whale Gusher mounted in the locker under the tiller, it is always ready to go NOW, and pumps on both strokes. With the extension handle for more leverage, the wife could easily pump and steer at the same time. Our LaVac head uses the same pump, and one hose clamp removed (under 1 minute) allows me to drop the hose from it, and get the same output, or maybe a little more because it's lower.

If there are others aboard, the two could be used simultaneously, and pump a lot of water. Of course the electric would also be pumping.

The whale gusher allows us the ability to switch up as needed. For instance, she could steer/pump while I locate the leak, we could switch while she gathered plugs and necessary repair gear, then we could switch off to make the repairs.


If all else fails we'll hit the flotation bags.

And I could remove more water with a spoon than the 1 cylinder Yanmar will.




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Old 07-04-2013, 03:10   #38
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Re: What do you all think of engine-driven bilge pumps?

Folks, it seems a big manual (or 2) works best. A lot of discouraging information here!
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Old 07-04-2013, 04:37   #39
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If you had a generator or inverter, would a household sump pump be something to consider? http://www.sumppumpsdirect.com/Wayne...ump/p6500.html
Is a 3/4hp pump that draws 4 amp and at 10' of head is 60 gpm. With a flat hose it would store easily. At $169, 2 of them would keep up with the 2" hole.
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Old 07-04-2013, 05:49   #40
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My engine mounted pump is 16,000 gph, how is a manual pump comparing to that? My biggest 12V pump is the Rule8000 with 3" piping which will still beat a person on the big manual pump; my guess is that after derating it still pumps more than 4,000gph. The engine mounted was tested at better than 10,000gph at 2,000rpm.
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Old 07-04-2013, 08:53   #41
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Re: What do you all think of engine-driven bilge pumps?

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If you had a generator or inverter, would a household sump pump be something to consider? Wayne EE980 - EE980 - 3/4 HP Energy Efficient Stainless Steel Cast Iron Sump Pump w/ Vertical Float Switch
Is a 3/4hp pump that draws 4 amp and at 10' of head is 60 gpm. With a flat hose it would store easily. At $169, 2 of them would keep up with the 2" hole.
If you can't mount a centrifugal pump on the front of your engine, the AC pumps are a decent choice. But as someone mentioned above, most of them have significant start up amp draws - often about 5 times the running amp draw. SO you just have to be sure your ac system (genset or inverter) can handle that start up amp rush.

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My engine mounted pump is 16,000 gph, how is a manual pump comparing to that? My biggest 12V pump is the Rule8000 with 3" piping which will still beat a person on the big manual pump; my guess is that after derating it still pumps more than 4,000gph. The engine mounted was tested at better than 10,000gph at 2,000rpm.
What do you have mounted on your engine (type/brand/model)? I presume its clutched?

Is the Rule 8000 still sold? I know they used to make 8000 and 4000, but can't seem to find on the web any of the really big Rule pumps.

You must have some big wires going to the rule. Where is it located - near the batteries, or is there a wire run to the bilge sump.
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Old 07-04-2013, 09:02   #42
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Re: What do you all think of engine-driven bilge pumps?

Raw water pumps as bilge pumps are possibly less smart and less effective than the apocryphal "motivated man with a bucket" method. It's like trying to put out a fire with a hair dryer.

I had a second PTO put on my new Beta 60 in case I ever wanted to install a engine sump pump, but my first lines of defense are a Rule 3700 and a couple more 2000 g/hr elsewhere, plus a Patay manual pump and a Y-valve for even the Henderson Mk. V I use to flush the Lavac (it's a good pump used to, uh... "debris".

But my main defense are three steel collision bulkheads, a full one forward and two half-heights either side of the engine room. On passage, we have shaped rubber bungs for the limber holes. Clearly, this isn't an option for most boats today, which have shallow, continuous bilges (I could have a couple of hundred gallons in just the engine room bilges before it got the stringers wet), but it does show the benefits of "area sumps" over "continuous" bilges.

The first seven feet of my boat could get mangled by a container and all we would lose are my tools, some of my ground tackle and most of my pointing ability. We could still float, still crawl downwind under sail and still motor. It wouldn't be pretty, sure, but it would likely be survivable. Some of the better fibreglass boats have at least one serious (meaning no penetrations for hose or electrical until well above the WL) collision bulkhead forward, because all the Plan Bs are pretty grim if you are holed forward.
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Old 07-04-2013, 09:07   #43
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Re: What do you all think of engine-driven bilge pumps?

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I know more than I ever wanted to about the Bounty . . . There's a ton of mis-information floating around about it . .

snip...

If all these pumps had in fact been in working order, they might well have survived, at least long enough to get to a shallow dock where they could rest the keel, because the combined capacity is absolutely huge. Before the replanking they apparently once were leaking 30,000gals/hr and the pumps kept up with it.
I concur completely, Evans. I've read all the gCaptain reportage (the best I've seen) and there and elsewhere, I've seen nothing that indicated that this wasn't the ship's "fault" so much as it was lax maintainance, lax training and a skipper who rolled with loaded dice against a hurricane.

I feel that the Bounty tragedy was among the more clearly avoidable of any of which I've heard. Having five vast pumps in non-working order is functionally identical to having no pumps at all. The prudent seaman must test and verify the state of his/her gear, especially his/her "save our souls" gear.
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Old 07-04-2013, 09:43   #44
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Re: What do you all think of engine-driven bilge pumps?

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\What do you have mounted on your engine (type/brand/model)? I presume its clutched?

Is the Rule 8000 still sold? I know they used to make 8000 and 4000, but can't seem to find on the web any of the really big Rule pumps.

You must have some big wires going to the rule. Where is it located - near the batteries, or is there a wire run to the bilge sump.
I have a Jabsco impeller pump mounted with electric clutch on my engine. It's impeller is as big as my hand and I'm 6'6"

The Rule8000 is in my keelsump. Wires not so bad at all. The 8000 is a dual 4000 with a smart manifold. It has two powerfeeds, one for each 4000 that is in it. They don't sell them anymore? Guess nobody cares about staying afloat anymore
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Old 07-04-2013, 10:44   #45
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Re: What do you all think of engine-driven bilge pumps?

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I have a Jabsco impeller pump mounted with electric clutch on my engine. It's impeller is as big as my hand and I'm 6'6"
:
What are the dimensions of the jabsco + clutch . . . . Mostly how far does it stick out in front of the engine?

When we built hawk we did the "double bottom" and "watertight bulkheads" thing, but I have always been a little sorry I did not mount a pump on the engine. We thought about it, but there was a trade-off with galley space, and at the time we decided to go with the better galley. But I would still love to find a way to do it.

We do have a big rule, and an AC pump that will run off our Honda, but neither of those are as good as a engine direct drive pump.
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