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sdowney717
07-19-2010, 09:09 AM
http://www.tongacharter.com/bilge.htm

interesting idea. Not that I want one.


The smallest Fast Flow pump will pump 24,000 gallons/hour at 2,000 rpm. just keep on moving in circles or the boat will sink.
2,000 shaft rpm is moving pretty fast.

chainyank
07-19-2010, 11:27 AM
what happens if you want to stay still and not sink? Wouldn't it be better to have it run off the flywheel, that way you could run it in or out of gear (or maybe that already exsists?)?

I have a plastic V-belt wheel mounted on the propshaft of my boat and always wondered if it was for some kind of pump.....hhmmm.......

davelaws
07-19-2010, 11:58 AM
A cleaver idea but not a new one. Wickstrom (Finland) manufactured a similar prop shaft pump about 60 years ago.
http://i895.photobucket.com/albums/ac158/dlaws_photo/WickyPump.jpg

Bob Cleek
07-19-2010, 03:30 PM
Yea, interesting, but I don't think I'd want that on my prop shaft. The entire engine to prop shaft linkage is all about forced normal to the shaft. None of the bearings in such arrangements are designed to take loading perpendicular to the shaft, such as this pump. I may well play hell with your bearings. Better to run a simila pump belted off the flywheel, whiere the bearings are designed to be up to the task. I'd expect a standard higher volume pump with a lever belt tensioning "on-off" switch would cost you a lot less than $500.

chainyank
07-19-2010, 03:45 PM
Bob, do you have any examples of such a pump arrangement? I have great access to the bilge under the flywheel, and have thought of just such a set up. I agree that a flywheel arrangement is a better plan, though I had not thought of an on-off clutch, of course.

ramillett
07-20-2010, 03:23 AM
Not too new , Rod Stephen designed that in every DUKW built back in like 1942 .

Ian McColgin
07-20-2010, 06:48 AM
Yep, been around. I don't see any side loading on the shaft. Looks a great idea both for the emergency and a wonderful, albeit expensive, vent. I've wanted one for years.

FSS172
07-20-2010, 07:34 AM
Yea, interesting, but I don't think I'd want that on my prop shaft. The entire engine to prop shaft linkage is all about forced normal to the shaft. None of the bearings in such arrangements are designed to take loading perpendicular to the shaft, such as this pump. I may well play hell with your bearings. Better to run a simila pump belted off the flywheel, whiere the bearings are designed to be up to the task. I'd expect a standard higher volume pump with a lever belt tensioning "on-off" switch would cost you a lot less than $500.

The way I read the text and interpret the pics this pump installs OVER the prop shaft not beside it therefore no side loads are being imposed on the shaft as Ian says. Also they say there are no bearing/contact surfaces in the thing. Apparently the thing is running all the time/anytime the shaft is rotating and functions as a bilge blower until/unless water rises to the intake. Interesting.....

Sailor
07-20-2010, 06:07 PM
So it doesn't need cooling water passing through it to keep from overheating?

Calliste
07-20-2010, 06:25 PM
A bilge blower ? How much air does it pump ? Will it starve my diesel of air ?


Douglas

Breakaway
07-23-2010, 09:26 PM
Why not use a T off the raw water intake, like this Groco Conversion Seacock? A trace of hose with a strainer at the intake end rests in the bilge. If need be, throw the lever and your engine is a bilge pump. Also makes winterizing a snap.
http://www.jamestowndistributors.com/userportal/woeimages/plumbing/32972_3.jpg (http://www.jamestowndistributors.com/userportal/show_product.do?pid=14693#)

Calliste
07-24-2010, 12:44 AM
Hi Breakaway , that is a v nice quote by Rudyard Kipling, T Y for sharing that !

My boat a BCC , named Calliste, already has a "Tee" and ball valve fitting, like that Groco conversion, that you suggest , but the raw water pump on my 3GM30F Yanmar has very little "Damage Control" pump volume capacity.

In an emergency my knee-jerk reaction is to start my motor, so that I have lots of voltage to power my emergency calls on Single Sideband and VHF Radios .

I also have an instantanious reaction, to drive my boat to land, and beach her , ASAP !

Given this tendancy of mine, for flooding control, I thought that this "always at the ready" , pump might be of a great passive value, for me.

A sistership owner has marked inside his cabin, a "Point Of No Return" , in which if flooding water reaches this point, he will abandon ship and "Climb Up" ,To His Life Boat.

These are thoughts that totally passed me by, while outfitting for extended Pacific Cruising, and only later caught up with me !

Most often when offshore sailors discover flooding, is when the floor boards start to float free, and the debrie in that flooded water will plug any normal pump strum box, ever so quickly and probably already has !

My assessment is that when I am using my engine , I am already near shore and not really sailing anymore, especially here in the tropics at 1 degree north.

So , in retrospect , this passive pump makes sense to me , but I don't want to starve air from my diesel , by evacuating fresh air from the engine compartment, which this pump might do ?????

I would be interested in any further thoughts that you might have on this mater, or from any other forum readers , out there .

Douglas

sdowney717
07-26-2010, 11:33 AM
this pump will pump a lot of water but would not pump out air to the point your engine is not getting any air. You must have air intakes or airflow designed into the area for the engine and it likely much bigger hole than this pump can pump. The fact is this pump is installed in some boats and nobody complained about engine starving for air so far. It is likely a good idea the pump is moving air out of the bilge constantly freshening the air down there if the air got stale or exhaust fumes carbon monoxide or explosive gases were present it would clear it out. And it does not waste much power to run it just pumping air, very little power. When water is being pumped more engine load but that is what you want.

Breakaway
07-26-2010, 03:02 PM
Only other thing I can think of to question about this pump is how much power it uses while pumping. That is, will you have enough to pump AND manuever, given the size of your engine (relative to the volume of expected water in a holing)

K

sdowney717
07-26-2010, 08:53 PM
The thing about those inline T fitting is this, if the water gets too high, the engine is going to be throwing water everywhere like off the flywheel etc... and might short out and shut down. The water pickup for the bilge needs to be as low down as possible.

Then if it runs the water down in the bilge and starts sucking in lots of air, it is going to burn out the rubber impeller and stop working completely.

Why dont they make centrifugal raw water pump designs, they would not easily burn out.

kulas44
07-26-2010, 11:21 PM
DetroitDeisel has had just that kind of bilge pump since befor time was invented. Crank driven nonetheless, and centrifugal. This ain't new, but shaft driven bilge pumps are just plain dumb.

Calliste
07-27-2010, 12:57 AM
Ahoy Kulas44, sounds like you know more than you are saying. For us dumber than dumb out here, would you clew us in on your "shaft driven bilge pumps are just plain dumb." , information ? Enquireing minds like to know!

Hi sdowney717, Gosh, I never passed my design engineer test, so I certainly don't know why our engines use impeller pumps instead of centrifical raw water pumps, just a mystery to me !

You can purchase impellers that can run dry for a while, but I am told that they are a bit abrasive to the pump rub plate and pump wall.

As for the "T" fitting and ball valve on the raw water line, I primarily use mine to flush out the raw water cooling circuit through the heat exchanger, when I plan to lay up the engine for a while, sort of a fresh water rince for the inboard , like we do with outboard's.

sdowney717
07-27-2010, 07:24 AM
The dumb part is somewhat understandable seeing the boat is going to be moving when the prop pump is working. And if you got a gear reduction turning at a slower speed than the engine, the pump wont pump at its fastest possible rate. I suppose you can view it as an idiot pump, kinda like an idiot light on the car always ready to go as your underway with no user intervention like turning on a pump clutch switch.

I often thought a centrifugal raw water pump would be best, no impellers or tricky seals to wear and then the pump stops sucking.
and I thought engine marinizers take the easy way out and perhaps even got incentives from impeller pump makers. Those things brake down often and need expensive parts.
The bilge is low enough in my boat that a centrifugal pump would pick up water.
Where it mounts on the engine would have to be low enough to pick up water.

ssor
07-27-2010, 09:13 AM
Centrifical pumps aren't self priming. The raw water filter is above the WL (at least on my boat). So priming the raw water pump would be required at some point and perhaps everytime the engine was started.

sdowney717
07-27-2010, 09:57 AM
it could have been done with a little fiddling on my engine mounting the pump low down on the motor.
perhaps engine designers, for I am sure they have reasons, like the idea of positive displacement pumps that literally SUCK .

I am positive that those impeller pumps also eat up engine horse power with the rubber blades rubbing against the housing.