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Old 16-01-2007, 01:26   #1
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Another Bilge Pump Thread

Disaster pumps

Has anyone installed an Ericson pump, or belted on a trash pump on your engine or kept a self contained trash pump onboard?

Ericson pump
Ericson Safety Pumps


trash pump found in Dashew's book, they recommended it because the pump is plastic
Engine Driven Pumps, Electric Motor Driven Pumps, Hydraulic & Pneumatic Driven, Pedestal Mounted Pumps, Magnetic Coupled Pumps, Vertical Pumps, Drum Pumps, Hand Operated Pumps - Pacer Pumps


Once I discovered flood rates compared to pump rates I started looking into alternatives for pumps normally found in places like West Marine.
I found a flood rate equation from an Ocean Navigator article I believe.
The Rule 3500 at about half rated capacity (to compensate for head/friction/voltage etc) is about 30 gal/min. That pump rate keeps up with about a 1 inch hole 1 foot under the waterline. A 2 inch hole 0.5 feet below the waterline is about 60 gal/min.

The smallest pumps mentioned above start at about 125 gal/min, which will keep up with a 3 inch hole 0.5 feet below the waterline.

The Ericson pump is interesting to me because it is in place always ready to go, but you have to put the boat in gear, alternatively you cound mount it on a PTO to avoid having to put the boat in gear, at which point a self priming trash pump could make as much sense. A drawback to the Ericson for me is that I have a V-drive. Dimension wise it looks like I can cram one in there, but I haven't figured out the mounting yet. On the plus side there is no maintenance.

If I put a trash pump on a PTO then it probably makes sense to have a clutch so you're not wearing out the bearings on the pump when you're not using it. Downside you have to engage the clutch and the main engine has to run, plus side, you don't have to have the engine in gear.

Having a pump with its own engine means that the boat engine doesn't have to operate, but you need get it out on deck, run hoses, and in between times maintain the pump engine so that you know it will run when you need it, you need to fill it with gas when you want to use it, or run it often enough that you don't varnish the carb, which then becomes another storage issue with something containing gas. Permanent mount gas engine belowdecks is not acceptable, price on diesel driven pump is not acceptable to me.

So those are my thoughts on a disaster pump. Anyone out there with something installed and how well it works?

Since I don't race and sail short handed mostly, manual pumps and buckets aren't the best solutions since the crew is likely to be busy in my opinion. And for the articles I've seen promoting using the engine cooling pump, my engine pumps 2 gal/min at idle, if it's linear with rpm that's a big 6 gal/min at speed. My boat came to me with two manual diaphragm pumps (10-20 gpm) and an electric diaphragm 6 gpm pump, which by the way was hooked up backwards when I got the boat. All those pumps go to the bottom of the keel. I have added a Rule 2000, it sits on top of the lead in the keel to make it accessable. The float switch on it is activated when there is somewhat more than 12 gallons of water in the keel. So this pump pretty much stays dry unless I have a problem. It also turns on an alarm at that point. Reading about trying to find the water ingress point once the hole was underwater inspired the alarm.

John
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Old 16-01-2007, 03:00   #2
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Approximate Flooding Rates, for smooth holes at selected depths, are calculated using the formula:
Flooding Rate in gpm = 20 x d x square-root of h
where:
d = diameter of hole in inches
h = depth of hole underwater in feet (head)

Hence, for a 2" dia hole at 3 Ft depth:
Q = 20 x 2" x root 3 = 20 x 2 x 1.73 = 69.2 gpm (4,152 Gal per Hour)
then
69.2 / 60 = 1.15 gal per second, or 2.3 gal in two seconds

The actual initial flow rate ('Q') will be less than calculated above, due to frictional & turbulance losses at the aperture.

Some excellent references:

“All About Bilge Pumps” ~ by David Pascoe
ALL ABOUT BILGE PUMPS - Boats, Yachts Maintenance and Troubleshooting

Why do Boats Sink?” ~ by Scott Thompson (Ocean Marine Services)
Why Do Boats Sink

”The Truth About Unsinkable Boats”
A professional mariner tells how you might avoid sinking
by Blue Water Sailing (staff)
boats.com - Feature: The Truth About Unsinkable Boats

”Sink-Proof Your Boat”
Keeping water out of your boat ... and what to do if it gets in
by Chris Caswell
boats.com - How To: Sink-Proof Your Boat

”BILGE PUMPING ARRANGEMENTS” ~ Maritime and Coastguard Agency (UK)
MSIS27 Chapter 6
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Old 16-01-2007, 14:48   #3
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If you got the equation from the boats.com article, I think he missed a square.

Q=20 x diam^2 x root(depth)

I can't find the article at the moment, and that article probably doesn't have any more credibility than the one at boats.com, but the equation I used gives values in line with the flood rate table in Calder's book.

Trying to make sense of this, I found a university website
http://www.me.sc.edu/fs/lyons/univ10...essure_lab.pdf

Q = area of hole x velocity of flow

area of hole is a square function of D, so diam^2 makes sense.

velocity of flow = root (2gh), h is the height of water above the hole,
so root(depth) makes sense.

So I get 139 gal/min, Calder has 136 gal/min, for a 2 inch hole at 3 feet.

John
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Old 13-04-2007, 11:02   #4
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Have you looked at the Jabsco pumps for this purpose?
51270 2 Bronze Manual Clutch Pump > Engine Driven Clutch Pumps > Bilge Pumping Systems > Jabsco - ITT
They look like a good alternative.

Paul L
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Old 13-04-2007, 12:40   #5
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John

Aren't you being a little paranoid?

If you lose a thruhull you can plug the hole. If you get holed by a reef or another boat chances are the flow will be too much to pump out. And even if you had a pump BIG enough to compensate for the flow rate, the motor may run out of fuel before you could get the boat back in for repairs, providing the motor would even run.

There is a limit to when one just has to except the circumstances and abandon ship..........................._/)
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Old 13-04-2007, 13:23   #6
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Not really. Electric pumps are pretty unreliable, they require a lot of juice, so the engine will need to be run any way. The point of the pumps is a holding action. It gives you time to find the hole and block it, or to make other plans.

Paul L
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Old 13-04-2007, 19:39   #7
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Quote:
Originally Posted by Paul L
Have you looked at the Jabsco pumps for this purpose?
51270 2 Bronze Manual Clutch Pump > Engine Driven Clutch Pumps > Bilge Pumping Systems > Jabsco - ITT
They look like a good alternative.

Paul L
I thought of that after I had posted this thread. They looked interesting in part because it would be a fairly small clean installation. These bigger pumps claim that they can handle some solids, but after all the warnings about being carefull with engine impeller pumps I'm leery about putting one in without a good strainer. They also seem to be relatively inefficient, the 65 gall/min pump uses 5 hp out of the engine, probably not much of an issue since this is only an emergency pump and maximising mileage out of the engine won't be a priority. And I think the biggest I saw was an 80 or 90 gal/min pump.

John
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Old 13-04-2007, 20:23   #8
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Quote:
Originally Posted by delmarrey
Aren't you being a little paranoid?

If you lose a thruhull you can plug the hole. If you get holed by a reef or another boat chances are the flow will be too much to pump out. And even if you had a pump BIG enough to compensate for the flow rate, the motor may run out of fuel before you could get the boat back in for repairs, providing the motor would even run.

There is a limit to when one just has to except the circumstances and abandon ship..........................._/)
For Puget Sound, maybe. If I manage to leave on my escape in about 3 years, No I'm not paranoid. There is a huge range of failures in between a thru hull failure and a massive hull breach. If for a few hundred dollars I get to stay out of a liferaft I'll consider it a bargain. The pump only has to run long enough for a repair good enough to considerably slow the leak. But a repair could take some time, 1.finding the hole, especially if it is under the water level in the boat, can make it very difficult to find, 2.getting to the hole, could take time even with an axe, 3.fashioning a repair, could be an irregular shaped hole in a awkward space.

If I'm busy bailing with a bucket, I'm not repairing the problem, and a 2000 gph pump won't even keep up with a hole the size of a typical thruhull.


As far as starting a trash pump, you've hit upon one of the reasons for the post in the first place, a discussion of pro's and con's of different kinds of engine driven pumps, whether independent or dependent on the main engine.


John
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Old 14-04-2007, 14:09   #9
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John,
Are you in the Puget Sound too? Do you know Mike & Liz on the Cal 40 Argonaut?

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Old 14-04-2007, 15:55   #10
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Quote:
Originally Posted by Paul L
John,
Are you in the Puget Sound too? Do you know Mike & Liz on the Cal 40 Argonaut?

Paul L
Yeah, I've met them at a couple of the Roaring 40s meetings. I've missed the last couple though.

John
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Old 16-04-2007, 09:05   #11
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Originally Posted by cal40john
Yeah, I've met them at a couple of the Roaring 40s meetings. I've missed the last couple though.

John
They are down in Mexico now. I helped them bring their Cal 40 from Seattle to San Francisco last summer. Nice boat.

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Old 08-07-2009, 14:32   #12
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Quote:
Originally Posted by GordMay View Post

...........
Some excellent references:

“All About Bilge Pumps” ~ by David Pascoe
ALL ABOUT BILGE PUMPS - Boats, Yachts Maintenance and Troubleshooting

Why do Boats Sink?” ~ by Scott Thompson (Ocean Marine Services)
Why Do Boats Sink

”The Truth About Unsinkable Boats”
A professional mariner tells how you might avoid sinking
by Blue Water Sailing (staff)
boats.com - Feature: The Truth About Unsinkable Boats

”Sink-Proof Your Boat”
Keeping water out of your boat ... and what to do if it gets in
by Chris Caswell
boats.com - How To: Sink-Proof Your Boat

”BILGE PUMPING ARRANGEMENTS” ~ Maritime and Coastguard Agency (UK)
MSIS27 Chapter 6
Those are excellent references, but the Scott Thompson and Maritime and Coastguard Agency (UK) articles do not appear to be available anymore.

The Pascoe article is very helpful, but appears to be dated as he says the alternatives to float switches are "too expensive". But the cost of the electronic switches is quite reasonable now.

Does anyone have experience with any of the new electronic switches? If they are reliable, they would appear to be preferable to the mechanical and prone to jamming old=style float switches.
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Old 08-07-2009, 15:16   #13
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Anyone who has pulled their knot meter for cleaning and tried to get the plug in knows how fast the water comes in down that low in the hull. I wonder how small an independent trash pump is available? Could it be mounted in an independent locker something like a propane locker?
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Old 08-07-2009, 19:32   #14
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Ericson safety pump

Well, I am still a year or so off the water but in addition to standard manual pumps and Edson electric bilge pumps I am installing a larger version of the Ericson safety pump - the ESP-80 which shifts 2400 l/min. Would have gone bigger if I could fit it in but the boat says NO. Mounted on the prop shaft this will only be of benefit when motoring. Considered running off the motor direct but no spare space. Could use any high volume centrifugal pump like a Tecumseh to achieve the same end but the Ericson pump is neat and tidy and just sits on the shaft quietly until needed.

Its main virtue is that it is automatically on if the motor is running. Seems to me that it is when the machinery is running that problems occur - not too much seems to happen when the sails are up. Can quote several instances of boats that have needed this sort of volume shifted or have been lost cos they did not have the capacity. Probably only occur one time, but... that is why Ericson call it their "safety pump" I guess. Small cost for big capacity reserve.

Have had other yachts with ESP fitted. Not needed - lucky me.
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Old 17-07-2010, 22:51   #15
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Quote:
Originally Posted by GordMay View Post
Approximate Flooding Rates, for smooth holes at selected depths, are calculated using the formula:
Flooding Rate in gpm = 20 x d x square-root of h
where:
d = diameter of hole in inches
h = depth of hole underwater in feet (head)

Hence, for a 2" dia hole at 3 Ft depth:
Q = 20 x 2" x root 3 = 20 x 2 x 1.73 = 69.2 gpm (4,152 Gal per Hour)
then
69.2 / 60 = 1.15 gal per second, or 2.3 gal in two seconds

The actual initial flow rate ('Q') will be less than calculated above, due to frictional & turbulance losses at the aperture.

Some excellent references:

“All About Bilge Pumps” ~ by David Pascoe
ALL ABOUT BILGE PUMPS - Boats, Yachts Maintenance and Troubleshooting

Why do Boats Sink?” ~ by Scott Thompson (Ocean Marine Services)
Why Do Boats Sink

”The Truth About Unsinkable Boats”
A professional mariner tells how you might avoid sinking
by Blue Water Sailing (staff)
boats.com - Feature: The Truth About Unsinkable Boats

”Sink-Proof Your Boat”
Keeping water out of your boat ... and what to do if it gets in
by Chris Caswell
boats.com - How To: Sink-Proof Your Boat

”BILGE PUMPING ARRANGEMENTS” ~ Maritime and Coastguard Agency (UK)
MSIS27 Chapter 6
Those flow rates are going to change as the boat fills up with water. Once it is full the flow rate will be zero. If you have a foot of water in the boat you now have to use the two foot equation and so on and so on.

Dan
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