How many bilge pumps?

[rslifkin]

Agreed on the bucket not being the answer. A person with a bucket can move a lot of water, but only for a limited period of time and only if you can throw the water out of the boat without moving (which is not the case on most boats more enclosed than a center console). Plus, if you're bailing, you're not fixing the leak.

[gwoiler]

I have wondered about the pump capacities. Is this with the pump in water and no hose on the outlet? So then, if I get a 4000gph I should be able to expect 2000gph with a 1.5" hose as short as possible. I ordered 2 different float switches and will wire them in parallel. Thanks for all the good information everyone!

[rslifkin]

Originally Posted by gwoiler

I have wondered about the pump capacities. Is this with the pump in water and no hose on the outlet? So then, if I get a 4000gph I should be able to expect 2000gph with a 1.5" hose as short as possible. I ordered 2 different float switches and will wire them in parallel. Thanks for all the good information everyone!

Yes, pump output is rated with nothing connected to the outlet. Depending on manufacturer, this may be at either 12 or 13.6 volts. I know Rule gives output vs head curves, some others only give data for open flow and 1 or 2 specific amounts of head.

In general, depending on installation, you'll likely see between 50 and 60% of the nameplate rating in the real world.

[GordMay]

Originally Posted by gwoiler

I have wondered about the pump capacities. Is this with the pump in water and no hose on the outlet? So then, if I get a 4000gph I should be able to expect 2000gph with a 1.5" hose as short as possible. I ordered 2 different float switches and will wire them in parallel. Thanks for all the good information everyone!

Electric bilge pumps are generally rated by their capacity, which is measured in gallons per hour, or gallons per minute, under open flow conditions, with no restrictions to the discharge; and don't consider such elements as the distance the water must be pumped upward [head] to the thru-hull fitting above the waterline, dips in the voltage supply [voltage drop], or drag created by corrugated hose [resistance], or other elements.

An actual discharge performance of 2,000 GPH, from a typical 4,000 GPH installation, is a reasonable assumption.

It's all calculable, by calculating 'open flow rating' LESS the losses due to:
Voltage drop
Head [pump performance curve]
Pipe/hose resistance
Other factors, such as check valves, etc.

[Elcapt]

I agree the pivoting float switches can be problematic especially if any squishy or other debris in bilge. Worst in open launches w leaves and picnic droppings .

My boat has a shallow bilge thus at sea , a pump either side is useful otherwise to dry it out otherwise the boat has to be set head to wind ; not fun in ocean passages .

I would still install a third pump 6”-10” higher up in case the others fail especially on a moored boat. Perhaps with a dedicated battery .

In addition we have a large hand operated bronze Edson pump.

For deep water voyaging I redirected the pumps through a siphon break in the lazarette and then out into the cockpit. No reliance on LEDs and fancy flow counters etc. you know exactly how much water is being pumped as it drains out the cockpit drains. Good way to minimize thru hulls .

Each pump direct wired and separately fused w blade fuses high up in cabin so cannot be submerged. Check them bi weekly. Keep a bunch of spares .They can subtly corrode in sea air causing non function at the worst time.

Also keep spare pumps. Even the best will fail without warning .

In conjunction make sure every thru hull valve works smoothly is greased and each has an emergency tapered wood plug
To shove in the thru hull if the hose breaks etc.

Knot meters and ssb ground plates further sources of subtle seepage !

[wing15601]

Identify all of your thru-hull outlets above the boot stripe. Trace back the one you can’t positively identify. It may someday be useful someday to have a diagram of all thru-hulls and where their hoses go.

[toda]

A few thoughts about bilge pumps: in 50 years of sailing and fishing on wood and FRP vessels, both off-shore and coastal, and 10 years in the marine towing and salvage world, I have come to the conclusion that it is hard to have too much pumping capacity if things go sideways!

I have Rule 5700 gph located at the bottom of the deepest point in the bilge, the float switch is mounted a few inches above it. There is a float switch cycle counter at the panel which lets me know if it has cycled, and how many times. There is a high-water alarm sensor located 8" above that. There is also a whale pump in the cockpit, with the pick-up next to the Rule. When offshore, I turn off the electric pump and do an hourly check of the Whale to assure that the bilge is dry. (Easy to have water flowing into the bilge unobserved if the primary pump is taking care of it unknown.) I have discovered otherwise secret sources of water into the bilge before they became problems this way: an unsealed opening inside the base of a forward stanchion (where the wire from the bow light was routed through a bulwark) in heavy seas with regular doses of green water on the foredeck; Another time when the cap on the the anchor chain deck pipe came off (again, in seas where green water on the foredeck was abundant); once from a water tank fill-hose that came loose, and once from a broken plastic fitting on the presssurize fresh water system.

I installed a 3-way valve on the thru-hull for the engine raw-water intake. There is a short section of hose attached to that which allows me to easily draw water from a bucket when doing engine maintenance while on the hard, or draw water from the bilge should the need ever arise.

Lastly, there are two spare Rule 5700 gpm pumps which are assembled with 20' lengths of flexible hose and 20' wires with alligator clips. Both of these are stored in the bilge. If needed, either (or both) of the hoses can be run up to the cockpit, and the clips connected directly to the batteries. While cruising, I have handed both of these pumps on occasion to other vessels which were taking on water, allowing them time to sort out their leaks. And it is lovely to have the peace of mind all rigged and ready to go should I ever need more pumping capacity myself.

Being able to get water out faster than it is coming in can go a long way toward reducing the mental stress associated with otherwise-simple puzzles (failed hoses, shaft seals, or any number of fairly minor gremlins) which can present even on a well maintained vessel.

One final note, I clean the bilge thoroughly (at least annually) or whenever it starts to look grimy. Pulling the pumps for cleaning, wiping any accumulated slime off float switches or from inside the screens of the pump intakes. There is ALWAYS something there to be wiped off which would decrease the efficiency of the pump. Bits of crud from the anchor locker which have made their way aft, the odd screw or scrap of tape or wire tie. Cleaning the bilge is the best way I know of to remain aware of what is happening in those secret places :-)

[manitu]

You give the passengers who panic a bucket each. The boat gets bailed, they are busy bailing so the don't do other stoopid things, and seeing the water-level go down while bailing will do more to calm their panic than anything you could say or do.

My boat got the Jeanneau/Benetau flat bilge without sump. Infact , because of the keel bolt reinforcements most of the bilge is tallest in the middle. The bilge is split in two by a 8" divider in front of the engine room, in center of the boat.

As of now, I got a Whale diaphragm pump (15ltr/min) in the starbord side of the rear sump. The boat tends to list a tiny bit to starboard in its home port without vacation gear. This pump is controlled by a Quick EBSN electronic bilge pump controller. Also got a big manual diaphragm pump in the rear sump, pump handle at the helm.

In the front bilge I got the same type Whale diaphragm pump (15ltr/m) acting as a combined shower/bilge pump. controlled by a simple electronic on/off switch, plus a momentary switch to empty it out after showers.
Also got a small manual diaphragm pump in the head locker.

In addition, I got a 1,1KW 240v stainless macerator pump with 2" hose on a 25m extension cord stored in the genset locker. Had the pump lying around, no reason not to store it in the boat.

I have considered using two pumps in parallel, feeding into non return valves. (in the rear bilge , at least)
The diaphragm pumps can run dry , so it would give me extra safety + a dry bilge under heel. But it also adds complexity and cost , and I havent sailed on one leg for days yet , so I hardly see the point as of now.

Edit: As I sail with my dog , I only use diaphragm and macerator pumps, all other designs seems to clog with dog hair. The standard cheap "propeller" ones are utterly useless.

.manitu

[DeValency]

Originally Posted by gwoiler

Hello all. My Beneteau 40cc has one electric diaphragm bilge pump and a manual whale. The electric pump works but does not really move a lot of water. I have seen 4000 gph pumps for sale. Should I have a second electric higher volume pump? What is your second pump? Thanks

A high volume centrifugal bilge pump is an absolute must you may want to install ASAP. I use 3700 GPH Rule (never, never go with clones, unknown etc. but only use the best possible pump from a well known brand you can find), a second is a Johnson 1,600 GPH, a third is a small one Johnson 500 in the bilge cavity under the propshaft stuffing box and I also keep an emergency portable 1/4 HP 115VAC at one of the lockers. That's in addition to a manual diaphragm pump operated from the cockpit. Never had to use any of these, except the mini Johnson for occasional draining of an increased dripping from the stuffing box. Each pump has a separate sensor.

As far as I remember, your boat may have a limited bilge depth where you want to install the pump, so make sure you have the space. You can install two low profile Supersub 1,100 GPH each Whale pumps if you have a limited depth.

[sailingharry]

So this discussion on optimistic flow rates and heads, and all that, is why I like the idea of sump pumps.


This page from RULE shows the 2000 with 2000GPH open flow. But at 8 feet of head (3 feet of lift, and 5 feet of dynamic head from flow restrictions) becomes a 1000GPH pump.
They do show a MASSIVE 8000GPH unit (Evacuator series), drawing 30A DC, that can move 3500GPH at 15 feet of head (and uses a 3" hose!). It appears to be unavailable anywhere, but Fisheries shows it out of stock at $500.
https://www.xylem.com/siteassets/bra...-bilge-iom.pdf


This 1HP pump from Home Depot for $300 shows a 82 GPM at 15 feet of head (and at that rate, you will have a LOT more dynamic head). That's 5000GPH, or 5 times more flow than that RULE 2000, and well above that imaginary 8000.
https://www.homedepot.com/p/RIDGID-1...RSDS/308759169


I'll agree, a trash pump is better. I'll agree, a gas pump is better. I'll agree, 3 gas powered trash pumps are even better. Give me a P-250 from my days in the Navy. And, yes, safety is everything. But there is a limit to what I can afford to buy and find space for on the boat! And even if I had a gas powered trash pump, the sump pump might still be a good extra!

[MicHughV]

I've had a few moments in my sailing career, where an electric bilge pump was inoperable for a number of reasons and a cockpit mounted hand pump had to be employed, while the crew was below with a bucket....
One can't always assume that an electric bilge pump is at your beck and call, especially true, when the batteries are being shorted out, as was the case for me.

The source of an onboard leak is not always immediately apparent either, especially so, with water over the floorboards...compounded by happening at night !!

In my particular case, it was up to me to ascertain the source of the leak, whilst a crew was busy with a bucket. Not until the source of the leak was found, was a return to the cockpit manual pump possible. In the meantime, the bucket was it !!

[rslifkin]

Originally Posted by MicHughV

The source of an onboard leak is not always immediately apparent either, especially so, with water over the floorboards...compounded by happening at night !!

In my particular case, it was up to me to ascertain the source of the leak, whilst a crew was busy with a bucket. Not until the source of the leak was found, was a return to the cockpit manual pump possible. In the meantime, the bucket was it !!

That's why, in my mind, you want as much automatically activated pumping capacity as possible (plus a high water alarm that triggers once you've overwhelmed the small nuisance water pump). The idea being to know about the problem and start searching before the water gets that deep (which makes finding the issue much harder). And that gives you a better shot of keeping the water from getting high enough to take out your electrical system.

[MicHughV]

Agree 100%....I've fitted a wailing siren alarm to the bilge pump electrical circuit, when the bilge pump is activated, I want to know why ASAP. My siren can wake the dead !!

I can't imagine why an alarm is not mandatory on any boat. I wouldn't leave the dock without it.

I've seen unattended boats at a marina sink, due to some other leak. An alarm would notify anyone within 100' there was a problem, giving a shot at saving the vessel.

[Cynara]

4000 gph is not much. The rating is usually based on zero head pressure. One you pump the water up 4 feet or more the output is much less. Find out how much water will come in a 2 inch or 4 inch hole and figure out how big or many pumps are required and how much power they would require.


Pumps will give you time to find and plug the leak if you have easy access to the area

[GordMay]

Originally Posted by Cynara

... Find out how much water will come in a 2 inch or 4 inch hole and figure out how big or many pumps are required and how much power they would require ...

Approximate Flooding Rates, for smooth holes at specific depths, are calculated using the formula:

Flooding Rate in gpm [Q] = 20 x d x h

where:
d = diameter of hole in inches
h = depth of hole underwater in feet (head)
h = square-root of h

Hence, for a 2" diameter hole at a 3 Ft depth:

Q = 20 x 2" x root 3 = 20 x 2 x 1.73 = 69.2 gpm (4,152 Gal. per Hour)

The actual initial flow rate ('Q') will be less than calculated above, due to frictional & turbulence losses at the aperture, but will increase as the boat sinks lower.

Note: A hole twice as deep allows in 1.4 times more water, and a hole twice as large lets in four times more water.