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Old 15-04-2013, 20:41   #76
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The concern with power loss is addressed my USL survey code (and probably most other codes) which requires more than one power source for bilge pumps - could be more than one motor, electric and motor etc. common sense really.
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Old 15-04-2013, 22:28   #77
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Re: What do you all think of engine-driven bilge pumps?

It seems pumps die more commonly from lack of use rather than overuse.

Human nature being what it is, it seems to make sense to me to make any engine driven pump have an additional non emergency use, ie deckhose and chainwash down, as is common on most fishing boats. That way the system is regularly used, and quickly repaired when it fails.

Don't hang the washdown hose overboard, a syphon can cause backflooding. Also, it might be a good idea to locate the outlet somewhere easy to see (like into the cockpit if it drains through the transom), so you can make sure it is still pumping. locating the outlet anywhere it could go underwater is a recipe for making the problem worse if the pump fails.

However one time I really needed a pump to work was in a mid Tasman blow on a square rigger. Wood chips washed into the bilge from behind the ceiling planks lining the hull and blocked the pipework. To make matters worse while checking the strumbox the bookshelf gave way, and the bilge filled up with trashy paperbacks. The engineer was incapacitated by seasickness. This impeller pump was regularly used and well maintained, with a good strum box and a filter. The blockage turned out to be in the pipework inside an elbow.

The hand diaphragm pump rubber failed when a wave nearly washed the two crew operating it away. They grabbed the handle, and all the loads went on the diaphragm which promptly tore. We latter fitted a lanyard to the handle to stop this happening again. This isn't a bad idea for any boat, as I have seen the whole pump body break, or be torn off from similar loads.

The centrifugal fire pump could not get a prime from it's on deck position. I really wished we had a few electric pumps then.

A large workboat I ran had a tee into the cooling water">engine cooling water so the bilge system could do double duty as an emergency engine cooling pump. I guess the volume of water could be an issue, if too much you might need to let some of it bypass the engine and go overboard, but might be handy.

I guess for me I feel that a couple of good big 12v electric pumps with very well waterproofed cabling and batteries together with some decent hand pumps and half height watertight divisions where possible to help isolate identify the source of any leak, plus a few buckets are going to keep me feeling much safer than I do when driving a car.

But I wouldn't argue with those that would prefer a large engine driven pump as well. I might even fit one day myself.
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Old 15-04-2013, 23:25   #78
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Re: What do you all think of engine-driven bilge pumps?

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The concern with power loss is addressed my USL survey code (and probably most other codes) which requires more than one power source for bilge pumps - could be more than one motor, electric and motor etc. common sense really.
That's a good point, but it's only strictly true to the extent that there are not vulnerabilities shared between different power sources.

For example: A genset might share the fuel supply with a propulsion motor, and both of them might rely on DC power for starting, possibly even for engine management.

When risks like these are are shared, it's arguably not realistic to consider them as alternatives to each other, or to a DC electric pump.

And one thing which tends to characterise emergencies at sea, especially ones to do with adverse weather, is multiple systems failing simultaneously - so anything which relies on more than one system is perhaps more risk-prone than it might at first seem.
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Old 15-04-2013, 23:48   #79
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Re: What do you all think of engine-driven bilge pumps?

SnowP: great story about the diaphragm ripping when the lever was used as a handhold.
I remember that thought crossing my mind during a trip across the Pacific a good while ago, when we were pumping 20 tons of water out of the bilge, noon to noon, with a big Edson.

(not, I hasten to add, for dear life; rather it was due to an idiosyncracy with the plumbing which meant we had to choose between allowing the 'self draining' anchor locker to drain via the main bilge, or risk submerging the windlass motor at the top of that locker - electric, not hydraulic, so we'd already gone through one motor before resolving this temporary solution ...

We had chanced upon a sort of 'runaway' trim problem, which meant that a few greenies over the bow would put enough water in the locker to depress the bow enough that every second wave would contribute a few more kilos....)

I forgot to note it down, as part of the hundreds of learnings from that trip (as with any long trip, even on a very well-found vessel).

So once again, thanks for bringing it up!

(I guess it's obvious that any boat with diaphragm pumps should either carry spare diaphragms, or suitable neoprene sheet material to make them en route. They don't need to be perfect to be a lot better than nothing...)

And if anyone reading this has successfully 'marinised' an aluminium Edson gallon-a-stroke pump, I'd be keen to hear from them.
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Old 16-04-2013, 14:03   #80
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Re: What do you all think of engine-driven bilge pumps?

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Evans,

Would you care to start a new thread and tell us a bit more about the Bounty?
I think it is best to let the USCG report come out. CMDR Carroll seems competent, so I am hoping his report will be definitive.

Regarding pumps . . . . anyone have any experience with "educator pumps" in "yachting size"?
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Old 16-04-2013, 19:04   #81
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Re: What do you all think of engine-driven bilge pumps?

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Regarding pumps . . . . anyone have any experience with "educator pumps" in "yachting size"?
I am only familiar with them being used to clean out residual product from tanker holds and their discharge line. Usually powered by air.
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Old 16-04-2013, 19:36   #82
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Re: What do you all think of engine-driven bilge pumps?

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Regarding pumps . . . . anyone have any experience with "educator pumps" in "yachting size"?
Did you mean Eductor pumps using a venturi/jet effect? A few of the ships I worked on had them, I do remember the engineers cursing them at times. Mind you they cursed most things outside the engineroom frequently, including us Deckies so that's no indication of worth.

Seems like a good concept to avoid any blocking, but if they go wrong they could pump huge volumes of water back into the space unless some sort of non return was fitted.

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I am only familiar with them being used to clean out residual product from tanker holds and their discharge line. Usually powered by air.
We used those little Wilden air driven diaphragm pumps quite often for stripping tanks and emptying void spaces. Often wondered if one could be modified to run on water pressure from an engine driven impellor pump, if so would make an ideal emergency dewatering pump.
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Old 17-04-2013, 10:06   #83
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Re: What do you all think of engine-driven bilge pumps?

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Often wondered if one could be modified to run on water pressure from an engine driven impellor pump, if so would make an ideal emergency dewatering pump.
Yes, that's what I was wondering about . . . if anyone had pursued that.
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Old 17-04-2013, 13:55   #84
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Re: What do you all think of engine-driven bilge pumps?

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Did you mean Eductor pumps using a venturi/jet effect? A few of the ships I worked on had them, I do remember the engineers cursing them at times. Mind you they cursed most things outside the engineroom frequently, including us Deckies so that's no indication of worth.

Seems like a good concept to avoid any blocking, but if they go wrong they could pump huge volumes of water back into the space unless some sort of non return was fitted.



We used those little Wilden air driven diaphragm pumps quite often for stripping tanks and emptying void spaces. Often wondered if one could be modified to run on water pressure from an engine driven impellor pump, if so would make an ideal emergency dewatering pump.
Hmm ... interesting train of thought. I wonder if anyone has ever thought of rigging a bow or stern thruster with a suitably slanted side entry from within the hull, so it can be opened with the thruster running to serve as a jet pump for emergency bulk dewatering? I'm not sure if there'd be enough pressure drop in a conventional thruster .... admittedly it's in the right part of the boat to self-prime, particularly if the entry's located at the bottom of the tunnel, and the subject vessel is dinkumly sinking.

If it worked, I'm sure someone would have done it (more particularly, in a jetboat, perhaps), but then again....

It's probably worth about as much as another wacky idea I had once, of connecting one or more of those big Edson gallon-a-stroke jobbies up to a flopper-stopper....

- - - - -

Jet pumps work rather well with steam, although they're still a bit temperamental.

(irrelevant ramble alert: Steam locos used to use them in pioneering times to rewater themselves from streams and rivers if they got caught short, but the crews had to look out for pondweed if using standing water... but I guess most sailboats don't have much in the way of a boiler. Somehow I don't think a domestic espresso machine would quite make the grade )

Getting down to more serious contemplation, and something which might actually lead somewhere useful:

I have a Wilden pump kicking around somewhere. I must try hooking it up to the mains water and see what gives. If it works, it would be interesting to compare the waste water from the power side with volume of water pumped; it should be simple enough to just run each to a separate bucket...

I'm guessing the volumetric efficiency and pressure ratio would both be much superior to a similar capacity jet pump

Remind me if you don't hear back.
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Old 17-04-2013, 14:08   #85
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Re: What do you all think of engine-driven bilge pumps?

PS: "educator pumps" made me smile:

Looks to me like it might be a case of good old SAMS (Software-Assisted Mis-Spelling) aka "spell checker knows best- itis"...

Another of my favourites of recent days is noticing an official NZ chart misidentifying one of our most well-known and best loved Capes.

Presumably thanks to the unperceived intervention of an ignorant spell checker, the name got Latinised from the beautiful Maori word "Reinga" to "Regina" !

Seriously, I have noticed a number of spelling mistakes in the latest issue of charts, and I guess it mainly reflects changes in human capacities, due presumably to changes in educational practices in the seventies and eighties filtering through to the higher echelons of the workplace

.... but I think spell-checking (with the implied message "You don't need to be able to spell, thanks to us!") has only made things worserer.
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Old 18-04-2013, 01:06   #86
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Re: What do you all think of engine-driven bilge pumps?

NERD ALERT!

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Originally Posted by Andrew Troup View Post
Hmm ... interesting train of thought. I wonder if anyone has ever thought of rigging a bow or stern thruster with a suitably slanted side entry from within the hull, so it can be opened with the thruster running to serve as a jet pump for emergency bulk dewatering?
The fish-farms around here use big outboard engines to pump large volumes of fresh water from liner to liner when bathing the fish, admittedly at very low heads. maybe someone clever could adapt this into a eductor/jet style pump or even a straight flow system that could attach to the dinghys outboard...

Quote:
It's probably worth about as much as another wacky idea I had once, of connecting one or more of those big Edson gallon-a-stroke jobbies up to a flopper-stopper....
I think I saw one of these advertised for dinghy's, clever idea for a low flow system. I guess solar panels have superseded this. I always thought windmill style pumps like the last sailing ships used was a great idea. Especially with an old wooden boat that leaks in rough water. I guess I was mostly thinking of it for movable ballast water management, back when water ballast was seen as a good way to go fast.

Quote:
I have a Wilden pump kicking around somewhere. I must try hooking it up to the mains water and see what gives. If it works, it would be interesting to compare the waste water from the power side with volume of water pumped; it should be simple enough to just run each to a separate bucket...
I would be very interested in the results.

Back when I was a kid we visited a remote homestead in pelorus sound called Te Puru. The whole place was powered by water from a dam up the hill. He ran almost everything of a million little peltin wheels including a fridge/ freezer, genset, workshop and haulout for his 30 odd foot yacht Waimarie. I always remember Bill opening a valve and the drill press starting up silently, with trickle of water running into a drain. A brilliant bit of renewable energy use from way before solar panels were invented.

Anyway the point of this ramble was that maybe more than just a pump could be run from an engine driven pump. Maybe the windlass could be driven off the washdown hose, and the waste water used to wash the chain. The Pump could also be used to run jets for a bow and stern thruster. Maybe even a weak jet drive. Probably completely impractical...

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.... but I think spell-checking (with the implied message "You don't need to be able to spell, thanks to us!") has only made things worse.
Big thanks to spell checker, without it I am completely hopeless, look at any of my posts from my phone...
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