Fast Flow Pumps (shaft mounted)

Anybody know about propeller shaft mounted Fast Flow Pumps which can run dry (moving air through the engine compartment) or spring instantly into action if you hole the boat while underway?

Fast Flow Pumps - Bilge Pump

Now that's interesting .... I'm all ears.

Works as long as you don't stop the boat. Plan A better be to beach the boat before going to neutral.

I like the idea from an emergency bilge pump or blower stand point. As to doing both, it would greatly depend on where the inlet is. For bilge pump, inlet needs to be as low as possible. For ventilation blower, inlet should be as high as possible. Would like to read some user reviews.

Ted

High Wire said:

Works as long as you don't stop the boat. Plan A better be to beach the boat before going to neutral.

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What if it's low tide in an area with tides over 20 feet, or there's miles of rock walls and steep shoreline to the next bay?

O C Diver said:

...Would like to read some user reviews.

Ted

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PDF of Practical Sailor article:

http://www.fastflowpump.com/Practical Sailor Magazine, Fast Flow Pump.pdf

The first rule of taking on water is damage control...

Reduce the incoming water and a turkey baste might be all you need.

Sure maximum pumping cabability will give you more time but what is your maximum?

I agree these kind of pumps are one of the best options...I just have no personal experience with them.

But generally.....concentrate on knowing how to stop/slow the water coming in....pumps are always the second line of defense.

MurrayM said:

PDF of Practical Sailor article:

http://www.fastflowpump.com/Practical Sailor Magazine, Fast Flow Pump.pdf

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Thanks, good review. Think the installation costs could easily exceed the cost of the pump. If I was looking for that capacity in an engine driven bilge pump, it would be a clutch (electric or manual) activated, traditional bilge pump.

A 4" bilge blower at <$50 would likely work better as installation could optimally position it to remove heat from the top of the engine compartment.

Ted

You can poke holes in any piece of equipment, and nobody is suggesting this be the only bilge pump aboard...it's just one more arrow in the quiver which could buy some time when it's most desperately needed.

I kinda like the idea of instant water evac while I try to .... a.) find the source. b.) correct the issue. It makes more sense to me than the reverse. I will be looking into this.

MurrayM said:

You can poke holes in any piece of equipment, and nobody is suggesting this be the only bilge pump aboard...it's just one more arrow in the quiver which could buy some time when it's most desperately needed.

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My comments were based on taking the total cost (pump and installation) and comparing it to other options with similar parameters. Nobody is suggesting it's the only pump on the boat as it's worthless if nobody is on board to start the engine.

To me it sounded like a good idea until I read the Practical Sailor article and began visualizing the installation with pillow block bearings and a flexible coupling to the crank shaft or a pulley drive system.

For your boat and situation it might be a very good fit. For my boat I see a bunch of compromises. When you post it here, expect people to offer their opinions. Don't like my opinion, ignore it.

Ted

O C Diver said:

My comments were based on taking the total cost (pump and installation) and comparing it to other options with similar parameters. Nobody is suggesting it's the only pump on the boat as it's worthless if nobody is on board to start the engine.

To me it sounded like a good idea until I read the Practical Sailor article and began visualizing the installation with pillow block bearings and a flexible coupling to the crank shaft or a pulley drive system.

For your boat and situation it might be a very good fit. For my boat I see a bunch of compromises. When you post it here, expect people to offer their opinions. Don't like my opinion, ignore it.

Ted

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Fair enough

The impeller comes in two pieces, bolts to the shaft, and spins without touching the pump housing.

MurrayM said:

What if it's low tide in an area with tides over 20 feet, or there's miles of rock walls and steep shoreline to the next bay?

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Implement Plan B.

High Wire said:

Implement Plan B.

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Whistling Dixie and looking skyward for assistance?

I've recommended them in the past and any boat in my future will have them.

If you really measure the output of your electric bilge pumps, they will only hold back sinking on minor inflow. They work in either direction, so will work either forward or reverse, since it acts like a centrifugal pump with some amazing specifications.

Yes, you do have to build up the area where the pump shell mounts, and provide a good path to exhaust the water being pumped out of the boat. You don't have to pull a shaft since everything is clam-shelled and splits to fit around the shaft. It may be inconvenient to mount on a V-drive boat since it would be under the engine.

Yes, you do have to leave the prop shaft spinning for it to work, but chances are, you're implementing plan A while it pumps hundreds of gallons of water overboard as you head to the beach.

With the varied skill, knowledge and emergency situation management experience in the boating crowd...

Lots will lose their $hite completely, others will dither, few will execute well...

There's a lot to be said for a device which requires no maintenance, no diagnosis, no interpretation, no intervention, and no delay. Water rises to the intake, and it just starts emptying the boat.

We all know boaters who need this sort of simplicity...

As luck will have it, I'd just be wasting time looking for a breach that ends up under a fixed sole, or otherwise inaccessible for heroic repairs... all the while taking on more water, with the bilge pumps still waiting for my Type A smarter-than-an-automatic-system personality to turn them on...

Anything that helps any boater stay afloat when it goes wrong, can't be a bad thing?

RB

stubones99 said:

I've recommended them in the past and any boat in my future will have them.

If you really measure the output of your electric bilge pumps, they will only hold back sinking on minor inflow. They work in either direction, so will work either forward or reverse, since it acts like a centrifugal pump with some amazing specifications.

Yes, you do have to build up the area where the pump shell mounts, and provide a good path to exhaust the water being pumped out of the boat. You don't have to pull a shaft since everything is clam-shelled and splits to fit around the shaft. It may be inconvenient to mount on a V-drive boat since it would be under the engine.

Yes, you do have to leave the prop shaft spinning for it to work, but chances are, you're implementing plan A while it pumps hundreds of gallons of water overboard as you head to the beach.

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How much vertical / horizontal shaft movement can they tolerate? While normally my shaft runs very smooth, when I dinged the prop last year, the engine, transmission, and transmission end of the prop shaft were moving around quite a bit. Obviously you get it fixed, but you still have to get to port.

Ted

It's only bad if people think that's step one in a one step emergency management.

And no I don't think boaters are stupid by any shot.

But I have either been teaching boaters or rescuing them for a long time.

And what Internet discussion outpaces the other by a long shot?

Bilge pumps over damage control.

If you have a serious issue, it's damage control that will save you over bilge pumps most of the time.

Even if the damage control that saves your boat is merely knowing where your thru hulls are and securing it, assuming it works as advertised.

So I think these pumps in theory are great...how much have I heard about them in the real world over reading? Not at all....and the early models I believe we're back in the 70s or early 80s.

So....to me it might or might not be a great idea....where are the real world testimonials and I don't mean off their website.?

Re the blower function, most boats in concern on these pages use passive ER ventilation, and many of these function on the ragged edge of starvation, as indicated by ER temp.
I would hesitate to further deplete the air supply by running an exhaust blower constantly.
Your engines thrive on cool clean air and even a moderately sized diesel gulps prodigious quantities of it. (Think about motor displacement x RPM)

Would a cheap 120v submersible pump work for an emergency situation? As long as the generator runs I guess.

Still a fairly low volume.

Oliver posted a good thread awhile back where on his Nordhan they used a large electric motor coupled to a crash pump...at least I think so.

If you want to actually lower water levels fast compared to serious flooding...you need to be up in the 1.5 to 2 inch trash pump arena. Even the dual 12V 3500 electric salvage pumps pale in comparuson.

The volume of a fast flow pump is about like a 6hp Briggs and Stratton with a raw water pump. It's what you see when the pros show up at a sinking to postpone the inevitable. The only difference is they are back there whirring along waiting on the water level to rise.

Ted, the gap is about 1/2 to 3/4 inch and is where the intake water comes in around the shaft. There is no intake port, just the gap around the outer shell.

Greetings,
Mr. 01. I suppose anything would help. I have a cheap sump pump to empty my water tank (550 gallons) so I don't have to overwork the Jabsco house pump but it only pumps max. 3000 gph (from memory-might be a lot less) so I wouldn't depend on it for backup of any kind in spite of the generator running.

Pumps similar to this can be easily "hard piped" into your bilge with a little bit of imagination.

http://www.waterpumpsdirect.com/Mul.../p14444.html?gclid=CJiH54CNxdECFZeXfgod3jgGiQ

But as mentioned, without a well thought out and even practiced damage control plan the average person is better off beaching it. Yes, even at low tide with 20' swings. Number one rule in damage control is knowing when to abandon ship and let insurance adjusters sort it out.

How about something like this?



150 gpm. Much smaller than a gas trash pump.

The biggest down side seems to be the need to operate in gear, and preferably at speed to get max pumping action. They quote 800 RPM as the lower end speed, and 2000 RPM at the high end. Even wide open my shaft only turns at 550 RPM. Now I know that's lower than many, but even with a 2.5:1 gear and 2500 RPM engine, that's only 1000 RPM at the shaft.

I also see three basic scenarios where you have a big enough hole to need such a pump.

1) You hit a rock pile and are taking on water. You may very well be stuck, so reving the engine up in gear doesn't sound like a good thing to do. And you may have trashed your running gear and not be able to run up the prop even if you wanted too. In this case, I don't think this type of pump would be at the top of my list.

2) You hit something out in open water like a dead head. Personally, I would stop the boat to assess what's going on and start damage control and pumping. I'm not sure taking the boat up to full speed would be my desired action. And if the hole faces forward in any way, which is almost certainly will, it seems that going fast will only cause more water to flood in, and maybe even increase the damage.

3) You hit something and start flooding, and there happens to be a nice beach nearby, and you conclude that beaching is the best action. This seems to be the only scenario where you would actually want to get underway rather than stop. And I think beaching would be a last resort after assessing damage, and after seeing how your pumping is handling the water inflow. I would only beach if sinking were inevitable. And as has been pointed out, beaching is often not an option, and/or grounding the boat is certain to total it, and it it's only about the safety of crew.

Bottom like to me is that it's a very narrow set of circumstances where it would be a benefit, and way more where it might actually make matters worse.

If you want a mechanically driven high volume pump, I'd go for a belt drive off the main, or even a PTO drive off the main or the gear if you have one. At least that way you can size things to give max pumping with the engine in neutral and running at a civilized RPM.

stubones99 said:

Ted, the gap is about 1/2 to 3/4 inch and is where the intake water comes in around the shaft. There is no intake port, just the gap around the outer shell.

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What about the gap between the top of the impeller and the top of the inside of the housing?

Ted

twistedtree said:

The biggest down side seems to be the need to operate in gear, and preferably at speed to get max pumping action. They quote 800 RPM as the lower end speed, and 2000 RPM at the high end. Even wide open my shaft only turns at 550 RPM. Now I know that's lower than many, but even with a 2.5:1 gear and 2500 RPM engine, that's only 1000 RPM at the shaft

Click to expand...

I was thinking that same thought. My shaft turns less than 600 rpm at cruise and 700 rpm max in gear.

Ted

After thinking about it a bit, due to this thread, I think it might be better if there were the same type vane pump mounted low on the engine and belt driven off the crankshaft. That way, any movement of the engine would also move the pump, and belt driven gives it a safety mechanism if something jammed the impeller. Mounting it low on the engine would let the water level rise more than at the prop shaft, but would be able to handle those of you who have low RPM at cruise, plus would let you keep pumping in neutral.

All we have to do now is find someone that supports all the marine engines around to make all the mounting brackets...

And a way to add 2 belts at least.