Bilge pump debate

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lipets

lipets

Senior Member
Joined
Jun 27, 2019
Messages
469
Location
USA
Vessel Make
Benneteau Swift 42
One of my pumps died so I'll replace it with a slightly larger one no big deal


I started researching how many Gph total should I have on a 42


Builder provided a manual 11gpm drawing from midship under batteries between engines operated by mounted handle in cockpit.


a 3gpm (which I'm replacing with an 8gpm ) this draws from midship also forward also drains shower. This is on a float switch



Also another 6gpm under the companion way



"The bilge pump system is not designed to provide buoyancy to the boat in case of damage.-The bilge pump system is designed to drive out the water being either sea spray or leaks but absolutely not the water coming through a hole in the hull, this hole being the result of a damage"




So I was going to add one or two pumps totaling 4,000 gph, but if that much water in coming in aren't the batteries going to get submerged and stop those pumps?


So I looked at the manual 30 Gpm Whale or Edson with the big handles, but who can keep up that physical work for hours on end until the leak can get slowed or help arrives.
This option looks better then adding two 12v pumps perhaps



stop/slow the leak

NERF footballs are very soft closed cell foam toy football
Great stuff foam
Truplug
soft wood plugs
toilet bowl wax


add your fixes.........




Then last resort life raft.............








 
"So I looked at the manual 30 Gpm Whale or Edson with the big handles, but who can keep up that physical work for hours on end until the leak can get slowed or help arrives.
'
The leak volume decides the work input, if it takes 30GPM to keep up, you will find the energy!
 
If you have a generator onboard, there are lots of options for 120 VAC pumps. Several people have mentioned portable trash pumps as a good option. There is another thread on the forum that discussed this quite extensively.

Ted
 
IF you're worried about sinking due to a hard grounding or collision, you're looking for an emergency trash pump, not an electric bilge pump.

Consider honestly what you're attempting to mitigate.
 
I have lots of bilge pumps but consider the manual pump to be a dry-the-bilge pump only, not one to be heroic like a Hornblower novel.

The serious part here is the escape plan. Just like a fire onboard, the fire-fighting devices are to get people out of the boat into the escape plan, not to “save” the boat. That’s what insurance is for.

Work on the escape plan.

If you buy a trash pump it will take more maintenance than an outboard motor. If you’re not up for that, nor wish to roam about doing freelance rescues nor going offshore, escape plan. Oh and stop pumping your shower into the bilge, that’s gross.
 
Not sure trash pumps require all that much maintenance



In the harsh environment of my assistance towboat ( deck locker of open boat).... running it for a couple minutes every two weeks or month and spraying it with water dispersant kept it running for years with only a pull or two.


When your boat is sinking, few pumps equal a decent trash pump.


But 4-5000gph in electric bilge pump is probably the best start... But not a final answer.
 
With a large hole, the pumps may not keep up, not even a trash pump.

A collision mat may slow down the water coming in. It's a large tarp with long lines attached that can be positioned over the hole from the outside of the hull.
 

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true.... damage control is a multi level event that bilge pumps are just part of.


collision mats in all but benign conditions are tough on short handed crews.
 
psneeld said:
Not sure trash pumps require all that much maintenance



In the harsh environment of my assistance towboat ( deck locker of open boat).... running it for a couple minutes every two weeks or month and spraying it with water dispersant kept it running for years with only a pull or two.


When your boat is sinking, few pumps equal a decent trash pump.


But 4-5000gph in electric bilge pump is probably the best start... But not a final answer.
Click to expand...

I used to carry a trash pump. I bought it so that I could carry fire fighting equipment. Luckily, I never had to use it for that purpose.

I have used it to help save a sinking boat, once.
I have used it to clean the gull/otter/heron/other poop from docks on several occasions.

Once I got bored with it, the regular running slowed to - occasional running, to - hardly ever, to - now it won't start, to - it is now off the boat.

One difficulty was that as it is a gas engine, I had no reasonable place to store it other than in plain sight on the Fly bridge, so I made a sunbrella cover for it.
Then it was still in the way and left unsightly messes when it was moved.

If my boating was different, or if my boat was large enough to have a better storage spot for a gas powered pump, I might carry one again.
 
psneeld said:
true.... damage control is a multi level event that bilge pumps are just part of.


collision mats in all but benign conditions are tough on short handed crews.
Click to expand...



One person could place the mat if the hole is in the bow area.

It takes two people to place the mat if beyond bow area.

Still better than not having a way to slow the incoming water.

Alternative is intentional beaching if far from haul out facility.
 
A belt driven 2 inch clutched Jabsco will remove about 200 G P Minuet, and can work as a fire pump if plumbed properly.

But of course the engine would have to be operating.
 
Depending on your wallet, plastic and stainless steel submersible trash pumps are available. Grainger lists a 1.25 HP model that pump over 100 GPM with a 15' total head.

Ted
 
I decided to test my pump today, ran about 100G into the bilge, started pump all looked good......until the breaker popped:eek:


Trash in the pickup, I thought the bilge was clean:nonono:
 
My feeling is that the automatic bilge pumps are for minor dewatering only. We have a 750 GPH pump in each of the three separate watertight areas of the hull, with another 750GPH manual backup in each area. If any automatic pump operates we get an indication on the dash.

I also feel that early notification is the key to overcoming a major flooding event. Because of this we have two independent early warning systems. One is a simple float switch on a siren. The other is through the boats alarm system.

To mitigate against a major flooding event we have a stainless steel 60 GPM 120 Volt pump that we can deploy to any area at literally a moments notice. We can also use that pump to help out a fellow boater if need be.

As a note of caution to those with large capacity DC bilge pumps. I have seen some claims of 4,000 GPH out of a DC pump that has #10 wire going to it. I think that is a real stretch, and these are probably at 0’ head and intermittent use at that.

My 60GPH pump is a continuous rating at a 10’ head, and the pump motor draws a bit over 10 amps AC. It is 10” in diamater and about 18” tall and weighs probably 20 pounds.
I find it difficult to believe that you can have that kind of capacity with a DC pump with #10 wire. Sorry.
 
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I think of bilge pumps as time machines. The more pumping capacity you have the more time you have to control the flooding, call for help, or prepare to abandon ship.

I’m not a big advocate of manual pumps. It takes a crew member to operate it when that crew member could be helping to stop the water coming in.

On a boat with a good sized engine, the engines raw water pump can move quite a bit of water. (I know, ruin the engine bla bla bla. If the boat sinks the engine is ruined. Clean your bilge once in a while.)

Big belt driven pumps on your engine and/or generator are good options. Think Jabsco clutch pumps.

If you want to carry a big trash pump, consider converting it to propane. The pump is not likely to get much attention and propane fueled engines are easier to start after sitting unused for long periods.

Always install the highest capacity pump sized for your discharge hose. It is very common for boat builders to install Rule 1500 pumps that use 1-1/8” hose. Why not install a Rule 2000 instead? Same hose size, same mounting hole pattern, more capacity. Pumps using 3/4” hose range from 250 gph to 800 gph, why not install the biggest you can?
 
I have a trash pump under my flybridge, dry and out of the weather. Come to think of it, I have not started it for about two seasons. Will it start? Complacency sucks.
 
Install a belted pump on the front of the noisemaker , and you will know weather the engine operates fairly often.
 
As far as I'm concerned, total automatically controlled bilge pump capacity on a boat should approximately equal the water ingress from a failure of the largest underwater fitting (typically a shaft log or engine intake thru hull).

Now, as far as actual as-installed capacity of a typical electric bilge pump goes, based on the performance charts published by Rule and others, I generally assume any small dewatering pumps (like an 800 gph) produce half of their rated output and anything big (like the the 2000s, 3700s, etc.) produce about 60%.

I'm currently in the process of re-doing the bilge pump setup on my boat, and the final setup looks like it'll be as follows: 1x 800 gph in each forward, engine room and aft bilge. Engine room will get a 3700 with a higher mounted float switch, aft will get a 2000 with a higher mounted float switch. Although I may have to change plans to 2x 2000 in the engine room bilge depending on whether I can fit the 3700 in an appropriate position (it's downright massive).

I may also add a good size 120V trash pump to the arsenal, allowing a real "holy crap that's a lot of water" situation to be managed by starting the generator and firing up the big pump. By the time I drown the starting batteries and generator to the point where I can't use it, I'd already be in very bad shape with engines half underwater. And that's also about the water level required to start getting electronics critical to running the bilge pumps wet.
 
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syjos said:
With a large hole, the pumps may not keep up, not even a trash pump.

A collision mat may slow down the water coming in. It's a large tarp with long lines attached that can be positioned over the hole from the outside of the hull.
Click to expand...

Seems like these might be helpful on some areas of the hull but challenging to deploy around keels or active fin stabilizers.
 
Like most emergencies at sea, lots of reasons, lots of solutions. Just another tool that is great in some situations but may not be as helpful or easy in others.


A waterproof or resistant barrier over a hull breach from the outside that water pressure help seal is great. ..getting it there, getting it to reasonably seal, and getting it to stay there in rough conditions presents a challenge. But look at the alternatives......
 
Yeah, the mat has its uses but I’d feel better with a variety of tools.
 

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rslifkin said:
As far as I'm concerned, total automatically controlled bilge pump capacity on a boat should approximately equal the water ingress from a failure of the largest underwater fitting (typically a shaft log or engine intake thru hull)...
Click to expand...

That's a great point. Welcome aboard :thumb:

Also, be aware of bilge pump location. Our boats bilge pump is located near the stuffing box and all the thru hulls are in the engine room, separated by a bulkhead and about a 1.5" diameter limber hole...

*Note to self: Install a pump to the engine room.
 
I've got a similar placement issue. The shafts and rudders will dump into the aft bilge (although water does feed to the engine room bilge). If there's enough water, it'll make it through the shaft holes in the bulkhead and end up in the non-draining space under the engines (unless it overflows the stringers, but that's unlikely without a totally missing shaft).

All but 1 thru hull is in the engine room, so that's the biggest point of concern. There's a single 3/4" thru hull in the forward bilge, but between a small pump in there and the limber hole to the engine bilge (which is downhill from the forward bilge), taking care of water from that would be no problem.
 
My boat has two fishholds, each with a ball-valved 1" thru-hulls (approximately 24" below sea level) to allow sea water in. Each hold also has an 800 gpm pump to take water out. The output of each pump also has a ball valve to restrict its flow. With both valves fulling open (so water is coming in thru-hull at full speed, and the pump pumping out as fast as it can), the pump can not only keep up with water flowing but full-drain the 250 gallon (?) hold in about 10 minutes).
 
MYTraveler said:
My boat has two fishholds, each with a ball-valved 1" thru-hulls (approximately 24" below sea level) to allow sea water in. Each hold also has an 800 gpm pump to take water out. The output of each pump also has a ball valve to restrict its flow. With both valves fulling open (so water is coming in thru-hull at full speed, and the pump pumping out as fast as it can), the pump can not only keep up with water flowing but full-drain the 250 gallon (?) hold in about 10 minutes).
Click to expand...

Did you mean GPH?
 
Then 800 GPH will handle a one inch hole. That is good to know information. Based on this article https://www.boatus.com/magazine/2014/december/bilge-pump-capacity.asp that 800GPH pump is actually pumping 400GPH approx with a real world losses as manufacturers use ideal situations for rating.

Good info, a one inch hole needs a 800 GPH pump to stay even.
 
depends on how deep the one inch hole is....
 
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