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Old 14-12-2016, 10:11   #1
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Massive bilge pump idea

So I was reading the story of the 39 foot aluminum hull Noah, sailed by Alexander Grefrath and crew, that went down on the 2016 ARC. Short story, they were on a well-found and ARC-compliant boat in moderate weather, and over a 4 hour period unsuccessfully battled slowly rising water levels without finding the cause. They abandoned the boat in a safe and orderly fashion with expectations that she would sink in the next several hours. Full story here:
Three crew and two children rescued from sinking yacht in Atlantic

It gets me to thinking about oversized bilge pumps.

Some background/basis for discussion:
  • For water volume, you could consider 40 feet long x 12 feet wide x 2 feet deep water x .3 (factor for hull shape not being a real cube) x 8 gallons per cubic feet, and you get about 2300 gallons of water. Let’s use that as a target volume that, if it could be removed, would have the boat perhaps dry enough to continue the fight to find the leak.
  • Practical Sailor did a report on super duty submersible bilge pumps a few years back (Sept 2010), all “labeled” as around 2000+ GPH pumps. They tested them through a 3 foot hose with a 3 foot vertical lift (a very low total head, in my opinion), and found them to max out at 1800 GPH – and with more hose/head, they would be even lower. Figure an hour and a half to pump out the 2300 gallons I’ve suggested. Maybe longer. Not a really good answer! Granted, if they had this in addition to whatever pumps they already had going, it would probably have sufficed.
  • Note that head loss in a pipe can be calculated. Assume 15 feet of 1.5” pipe at 3000 GPH. Assume two 90 degree fittings at 5 feet (effective length) each, for a total of 25 feet of pipe. 100 feet of 1.5” pipe at 3000 GPM has a head loss of 14 feet, or 3.5 feet of head for 25 feet of pipe. Add in another 3’ of head for lifting out of the boat, and we’re talking 6 feet of total dynamic head. Good reference here: Plastic Pipes - Friction Head Loss
  • Engine driven pumps are a big improvement. For $1200, plus whatever it takes to hang it on your engine, you can get a Jabsco 50270 that puts out 60 GPM/3600 GPH and self primes to 8 feet. This would have saved the yacht, for sure. Even if they couldn’t find the leak, they could have run the engine for ˝ hour every 4 hours, and sailed for the nearest port. But it’s an expensive option. Note that a rubber impeller pump is essentially a positive displacement pump, and as such has little loss with hose runs.
  • Even a 20 GPM manual pump would take 2 hours to pump out the water that accumulated in 4 hours – that’s a tiring task!

So, now for my thought. Yes, if you can physically fit an engine pump, and can afford an installed cost of $2K or so, then it’s a slam dunk. But how off the wall is this idea. A swimming pool pump has a powerful pumping profile. A 1 HP unit can be easily run off an inverter or generator (draw is under 1kW – theoretical 750W maximum -- and the actual pump power of this installation can be calculated at under 3/4 HP using a 60% pump efficiency). Note that a 100A alternator will essentially provide all power requirements, so battery will not be drawn down. A Hayward 1HP pump has performance specs here: Hayward Super Pump 1 HP Single Speed - SP2607X10 - INYOPools.com that show for 20 feet of total head (lowest plotted value), it can produce 85 GPM or 5000 GPH (and yes, that means that the head calculation above is wrong – but still a lot of flow!). The pump will self prime to 10 feet, and they come standard with a big, easily serviced strainer. And installation is much more flexible than an engine pump.

A pool pump at under $500 (and Hayward is a premium brand – other brands cost even less), easily installed, with a 1kW inverter and a 100 Amp alternator (many cruising boats have at least this combination) would have emptied that sinking boat in under 30 minutes. This combination is 1/4 the cost of an engine driven pump, with 50% more flow rate.

Thoughts?

Harry
Rantum Scoot
’79 Sabre 34
Mill Creek, Annapolis
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Old 14-12-2016, 10:17   #2
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Re: Massive bilge pump idea

Other than the possible salt water problems and that a pool pump motor is not meant to be submerged, no.
Just I assume have to mount it high enough that it won't get wet.

Oh and the couple of pools that I have had that had about a 1', maybe 2' head, I always had to prime the pump after emptying the basket, not a major deal if your prepared to prime.
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Old 14-12-2016, 10:22   #3
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Re: Massive bilge pump idea

How about this one....... WilTec - Trash Water Pump V2200F with float switch 42000l/h with 2200W Trash Water Pump V2200F with float switch 42000l/h with only 2200W 50988

Dockhead has one and has written about "crash pumps" or "trash pumps" in another thread.

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Old 14-12-2016, 10:26   #4
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Re: Massive bilge pump idea

What are you going to do when the water hits the batteries?

The difference between recreational boats and military design - battle damage control redundancy. Most sailboat batteries are placed as low center of gravity as they can. Your pump idea was viable except for relying on the alternator and electrical system.

Just go with an Ericson safety pump and don't leave port with mysterious water ingress because of an event.
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Old 14-12-2016, 10:45   #5
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Re: Massive bilge pump idea

Quote:
Originally Posted by SV DestinyAscen View Post
What are you going to do when the water hits the batteries?

The difference between recreational boats and military design - battle damage control redundancy. Most sailboat batteries are placed as low center of gravity as they can. Your pump idea was viable except for relying on the alternator and electrical system.

Just go with an Ericson safety pump and don't leave port with mysterious water ingress because of an event.
In my boat if the water gets there which is about a foot over the cabin sole, I'm afraid the battle is lost anyway, and in my boat, the main engine's air intake is likely under water at that point too, so you have lost it and the generator. Batteries will provide power submerged, yes there will be some loss and eventually they will be trashed as salt water gets into the cells, but its not immediate.
Way I see this going down is your sailing along, I assume in bad weather and the high water alarm goes off, you jump down and open the bilge to find of course a lot of water. You cuss and scramble to get the collapsible hose connected to the pump and turn it on, running the hose of course overboard.
One of two things is going to happen, the water level will begin to decrease, meaning you have bought considerable time I hope and you start looking for where the water is coming from in the hopes of stopping it.
Or, water level increase slows some meaning you haven't bought much time, you have only a short time to find and stop the water ingress or prepare to abandon ship
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Old 14-12-2016, 10:49   #6
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Re: Massive bilge pump idea

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Originally Posted by captmikecoin View Post
How about this one....... WilTec - Trash Water Pump V2200F with float switch 42000l/h with 2200W Trash Water Pump V2200F with float switch 42000l/h with only 2200W 50988

Dockhead has one and has written about "crash pumps" or "trash pumps" in another thread.

Mike
That's equally "out of the box," and I like it. 10000 GPH, or double the pool pump. But it's 2kW (perhaps harder to run on an inverter) and 220V, which doesn't exist on most US boats. Still, that's an interesting place to start looking. "Trash" pump means it can handle the trash, and submersible means that it can probably handle the marine environment (with recognition that it better never actually see water until it is needed!).

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Old 14-12-2016, 10:50   #7
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Re: Massive bilge pump idea

Unless you are going to install a 6 inch diameter hose with sufficient small radius bends from the bilge overboard, this exercise is entirely academic. Plus you will need a 6inch hole in the thruhull location to discharge the water.

For a larger desired flow rate, you would need to increase hose diameter proportionally.

Are you designing a submarine?
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Old 14-12-2016, 10:52   #8
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Re: Massive bilge pump idea

No you don't need anything more than a roll up hose maybe three inches in diameter.
This one is over 4,000 GPH
Koshin 1/2 HP Submersible Trash Pump-PKS-65011 - The Home Depot

This one is tiny and gasoline and over 2,000 GPH, I have this motor on a bicycle, it's a tine weed eater type motor and runs really, really well. This I would use that canned gasoline that stores for a very long time, not ethanol pump gas
http://www.northerntool.com/shop/too...5735_200585735
I run 100LL airplane gas in my bicycle and have done so for years and it runs fine with no carburetor problems, but 100 LL isn't widely available
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Old 14-12-2016, 10:54   #9
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Re: Massive bilge pump idea

I don't understand not being able to find the source.
  • Through hulls. Check them all and close them. Could be in the plumbing as well.
  • Rudder post. Should be visible.
  • Crack in hull. Should be visible. If not, go for a swim. I'm not saying it's an easy swim, but head the boat down wind, rig a drogue, and go.
I also don't understand "blue water" boats without some level of bulkheading. I think that is an oxymoron. They don't need to go to the deck, but there should be some means of controlling flooding. The rudder post can be in a large crash tank. The bow can be a large crash tank. Not only do crash tanks protect a zone, they also provide a lot of flotation, slowing flooding. We shouldn't be storing heavy things in either place anyway. Most of the through hulls can be in a bullheaded compartment. A few bulkheads you have to step over can help.


I had a through hull fail once (PO installed a transducer wrong). It was in a bullheaded compartment and no damage was done.


It can be done. Designers chose not to, perhaps because we would complain about the chopped up interior. Which means we have chosen not to buy a boat that is as safe as it could be.
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Old 14-12-2016, 10:56   #10
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Re: Massive bilge pump idea

Quote:
Originally Posted by SV DestinyAscen View Post
What are you going to do when the water hits the batteries?

The difference between recreational boats and military design - battle damage control redundancy. Most sailboat batteries are placed as low center of gravity as they can. Your pump idea was viable except for relying on the alternator and electrical system.

Just go with an Ericson safety pump and don't leave port with mysterious water ingress because of an event.
The Noah (the boat that got me thinking) didn't lose electric pumps (due to battery flooding) until nearly 2 hours after their first report to Race Control. Once their electric pumps failed, they were basically toast -- nothing left but manual pumps.

The Ericson pump is a neat idea. Probably harder to fit than the brochure indicates (my Sabre 34, when it had a stuffing box, required the engine to be moved just to get enough room to replace the packing!). Not sure many boats have enough shaft room to fit the pump -- both free length of shaft, and clearance over the hull.

Harry
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Old 14-12-2016, 10:59   #11
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Re: Massive bilge pump idea

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Originally Posted by S/V Illusion View Post
Unless you are going to install a 6 inch diameter hose with sufficient small radius bends from the bilge overboard, this exercise is entirely academic. Plus you will need a 6inch hole in the thruhull location to discharge the water.

For a larger desired flow rate, you would need to increase hose diameter proportionally.

Are you designing a submarine?
Pool pumps through 1.5hp are designed with 1.5" piping, which is only 1/4" larger than most large bilge pumps. As far as the thruhull, this would work very nicely installed very high on the transom (within and inch or two of the rail) since water dribble and other cosmetic concerns are not going to be a concern on a never-used system. And the head loss calculations I did were based on 1.5" piping, not 6" piping.

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Old 14-12-2016, 11:10   #12
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Re: Massive bilge pump idea

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Originally Posted by thinwater View Post
I don't understand not being able to find the source.
  • Through hulls. Check them all and close them. Could be in the plumbing as well.
  • Rudder post. Should be visible.
  • Crack in hull. Should be visible. If not, go for a swim. I'm not saying it's an easy swim, but head the boat down wind, rig a drogue, and go.
I also don't understand "blue water" boats without some level of bulkheading. I think that is an oxymoron. They don't need to go to the deck, but there should be some means of controlling flooding. The rudder post can be in a large crash tank. The bow can be a large crash tank. Not only do crash tanks protect a zone, they also provide a lot of flotation, slowing flooding. We shouldn't be storing heavy things in either place anyway. Most of the through hulls can be in a bullheaded compartment. A few bulkheads you have to step over can help.


I had a through hull fail once (PO installed a transducer wrong). It was in a bullheaded compartment and no damage was done.


It can be done. Designers chose not to, perhaps because we would complain about the chopped up interior. Which means we have chosen not to buy a boat that is as safe as it could be.
I am equally curious about not being able to find the source. However, they were in communication with event organizers who provided some input and suggestions, and I would assume that "close thru-hulls" was mentioned at some point. Also, most organized offshore events have considerable prep requirements, and I suspect that would rule out complete greenhorns. I have to assume it wasn't easy.

As far as bulkheading, I'm not sure it would be all that easy. I have thru-hulls in my engine compartment, lazarette, forepeak, head, and galley. I can't imaging ANY way of making those compartments watertight -- and if I did, that would naturally mean individual bilge pump systems for each one (can't drain to the main bilge) for a total of 5 bilge pump systems on a 34 foot boat! It can be done, for sure, although as you mentioned few people would appreciate the layout and fewer would appreciate the cost. If that is the accepted standard for offshore capable boats, there would be few that would be able! Certainly no coastal cruisers that could be upgraded for that use.

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Old 14-12-2016, 11:11   #13
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Re: Massive bilge pump idea

I plan on having a trash pump stored in a locker with an electric plug and a roll up hose.
If I start taking on water, drop the pump into the bilge after connecting the roll up hose, take the hose up the companionway and toss it overboard, plug in the pump, start scrambling to find the leak.
Pump I linked to is cheap and according to the specs will eat 3/8" solids, I should not have anything that big in my bilge.

Some boat have liners that may make finding a leak tough, as far as diving the boat, I have done so years ago in small maybe three ft waves max to cut off a line wrapped around the prop. Let me tell you, it liked to have beaten me to death that boat motion seems gentle until you get into the water with it, then it is like being in a pen with a Bull, I can't imagine being at sea in bad weather with real waves. I'd try it of course if that was all I could do, but it may be that I couldn't handle it, much less do anything about a breach if I found one.
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Old 14-12-2016, 11:13   #14
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Re: Massive bilge pump idea

The problem with relying on batteries is even if the Noah's crew were able to find the leak, slow it with rudimentary plugging, once the batteries got wet it is a matter of time Before it goes.

Say your two hour hypothetical, you had the boat relatively dry again with your contraptions and located the source of the leak, the battery will still probably die. IOW, mean time until failure becomes unacceptable once water hits the batteries.

To me good redundancy design considers the dominao of things that can go wrong and you start with the most reliable system to build your checklist from.

A battery system requires a functional diesel - a diesel powered system bypasses the electrical.

So why use the battery system? It'll be no more redundant than fitting a larger electrical proper bilge pump.
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Old 14-12-2016, 11:27   #15
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Re: Massive bilge pump idea

It s a matter of being reasonable.
Ideal is a boat that can't sink, either being positively buoyant when full of water, or having water tight doors and bulkheads, all thru hulls in a sea chest etc. Unfortunately most of us don't have that, and couldn't afford it anyway.
I have limited funds, it may be that I have to go without satellite phones, large life rafts etc. I have to make do with the funds I have and address the most probable problems, I'm not preparing for an EMP or meteor strike as I think them unlikely.
However I think having a way to de-water the boat not a bad idea, I wish I had it a couple of years ago when I towed a guy back that they had flipped their little boat, I may have saved them some grief.
In my installation I would have two single points of failure, the pump itself of course, and the inverter. But you do the best that you can with what you have.

Once I think about it, I would only have one single point of failure as I have a generator, that is the pump
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