Bilge Pumps 101
01-02-2009, 09:55 PM
#1
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Bilge Pumps 101
I am rebuilding my boat, a 35ft deep V and have two 1100 gph Rule bilge pumps, both with non solid state float switches and both mounted on pads at about the same height. They are both wired to seperate batteries.
Wanting to do things right before the engines are replaced, I am thinking:
1/ Replace one or both of the bilge pumps even though they have not seen a lot of use.
2/ Use a float switch on one only.
3/ Mount one about an inch or so higher than the other.
4/ Mount one as low as possible without a bracket.
5/ Remove 90 degree corners on outlet hoses.
6/ Using a thermal overload instead of a fuse or breaker so they come back on automaticaly.
7/ Not increasing to bigger pumps.
Any feedback would be most appreciated.
Wanting to do things right before the engines are replaced, I am thinking:
1/ Replace one or both of the bilge pumps even though they have not seen a lot of use.
2/ Use a float switch on one only.
3/ Mount one about an inch or so higher than the other.
4/ Mount one as low as possible without a bracket.
5/ Remove 90 degree corners on outlet hoses.
6/ Using a thermal overload instead of a fuse or breaker so they come back on automaticaly.
7/ Not increasing to bigger pumps.
Any feedback would be most appreciated.
01-03-2009, 12:23 AM
#2
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Most bilge pumps have some sort of impeller that can age with time. I would replace the pumps with new ones at least that size AND use solid state switches with both mounted as close to the bottom as I could get them. Pu new hose on the nad get rid of any 90's. Make sure your connections are as far above the bottom of the boat as you can get them within reason and make sure they are water proof. Place the at least higher than the battery tops.
There are other places I would try to save money but not here...this is cheap insurance.
http://www.boatus.com/boattech/casey/14.htm
Installing a Bilge Pump
by Don Casey
Bilge pump installation is straightforward, but it is essential not to overlook key details.
Mount the pump
You must not place the pump in the bilge unrestrained. If it falls over it will suck air and burn out. Pumps must be fastened down. Brackets are available that attach to a stringer or other vertical feature, or you can epoxy a couple of bolts to the bottom of the bilge to serve as mounting studs.
Float switches must also be fastened.
Use smooth-bore hose
Corrugated hose reduces pump output by as much as 30%, so always connect the pump to the discharge fitting with hose that has a smooth interior surface.
Bends and long runs also reduce pump output, so make the hose run as straight and as short as possible. That may mean discharging the pump through the side of the hull rather than through the transom. However. . .
Place the discharge above the waterline
If the discharge is submerged when the pump runs, the ocean siphons back through the pump into the bilge when the pump shuts off. When enough water has entered to float the switch, the pump will eject it, only to have it siphon back again. This continues until the battery is depleted, then the water floods the boat until it reaches a level that gets the crew's attention.
The discharge fitting must never go below the waterline. If the fitting is through the transom, be sure it is high enough not to submerge when the stern squats. And if it is through the side of the hull, it must be high enough to remain above the water at the deepest angle of heel.
Use a thin-wall fitting
The through-hull fitting can further reduce pump capacity. To minimize this restriction, use a fitting with the largest possible opening.
Lead wiring up
It is essential to get the pump wiring out of the bilge as quickly as possible. Run the wires up and secure them so that they do not sag into the bilge water.
Don't skimp on wire size
A 3,500 gph pump will draw 15 amps, typically necessitating 10-gauge, or maybe even 8-gauge wire. Consult the ABYC Wire Size Table to determine the appropriate wire for your pump and length of wire run.
Use butt connectors and heat shrink
Crimp-on step-down butt connectors will assure a good mechanical and electrical connection between the supply wires and the pump leads. Enclose these connections in adhesive heat shrink tubing to make them water tight. You must slide the heat shrink over the wire and out of the way before you make the connections. Then center the tubing over the crimped connector and shrink it with a heat gun or by playing a flame beneath it. Be sure there are no explosive fumes in the bilge!
Connect to the battery
When you turn the power off to leave the boat unattended, you don't want to turn off the bilge pump. Connect an automatic bilge pump directly to the battery, not through the distribution panel.
Fuse the positive side
It is essential to have a fuse in the positive wire as close to the battery as possible. Some switch panels (see below) include a fuse. Otherwise join an in-line fuse holder to the battery end of the positive wire using a crimp butt connector.
Install terminal fittings
Do not strip the ends of the supply wires and loop them beneath the battery terminal wing nuts. Install crimp-on ring terminals the proper size to fit the threaded posts on your battery. Use a copper washer-not steel-between the wing nut and the ring terminal.
Three-way switch
If your bilge pump has a separate float switch, you may want to wire it to a three way switch that allows you to select automatic, on, or off. Be sure to support all wire runs at least every 18 inches using cable clamps or ties.
Two pumps
A bilge pump big enough to deal with a real emergency will do a poor job of keeping the bilge dry because the water in the discharge hose drains back into the bilge when the pump shuts off. And a big pump requires a big hose.
The ideal bilge pump arrangement is a small (400 gph) automatic bilge pump mounted in the sump to dispense with rain and shaft-gland leakage, combined with a high capacity pump (3,500 gph) mounted higher to deal with more serious ingress.
Stepping the discharge hose from the small pump down to 1/2-inch minimizes the backflow from the hose when the pump cycles, maintaining a dryer bilge. The large pump can be wired to a float switch if you prefer, but I think a manual switch makes more sense. An added advantage of this bilge pump configuration is that the high-capacity pump sits high and dry, extending its life indefinitely.
The ABYC Wire Size Table, a more complete explanation of the two-pump system, and other information about bilge pump installations can be found in This Old Boat by Don Casey.
Go to BoatTECH Guides : Go to Don Casey Library
There are other places I would try to save money but not here...this is cheap insurance.
http://www.boatus.com/boattech/casey/14.htm
Installing a Bilge Pump
by Don Casey
Bilge pump installation is straightforward, but it is essential not to overlook key details.
Mount the pump
You must not place the pump in the bilge unrestrained. If it falls over it will suck air and burn out. Pumps must be fastened down. Brackets are available that attach to a stringer or other vertical feature, or you can epoxy a couple of bolts to the bottom of the bilge to serve as mounting studs.
Float switches must also be fastened.
Use smooth-bore hose
Corrugated hose reduces pump output by as much as 30%, so always connect the pump to the discharge fitting with hose that has a smooth interior surface.
Bends and long runs also reduce pump output, so make the hose run as straight and as short as possible. That may mean discharging the pump through the side of the hull rather than through the transom. However. . .
Place the discharge above the waterline
If the discharge is submerged when the pump runs, the ocean siphons back through the pump into the bilge when the pump shuts off. When enough water has entered to float the switch, the pump will eject it, only to have it siphon back again. This continues until the battery is depleted, then the water floods the boat until it reaches a level that gets the crew's attention.
The discharge fitting must never go below the waterline. If the fitting is through the transom, be sure it is high enough not to submerge when the stern squats. And if it is through the side of the hull, it must be high enough to remain above the water at the deepest angle of heel.
Use a thin-wall fitting
The through-hull fitting can further reduce pump capacity. To minimize this restriction, use a fitting with the largest possible opening.
Lead wiring up
It is essential to get the pump wiring out of the bilge as quickly as possible. Run the wires up and secure them so that they do not sag into the bilge water.
Don't skimp on wire size
A 3,500 gph pump will draw 15 amps, typically necessitating 10-gauge, or maybe even 8-gauge wire. Consult the ABYC Wire Size Table to determine the appropriate wire for your pump and length of wire run.
Use butt connectors and heat shrink
Crimp-on step-down butt connectors will assure a good mechanical and electrical connection between the supply wires and the pump leads. Enclose these connections in adhesive heat shrink tubing to make them water tight. You must slide the heat shrink over the wire and out of the way before you make the connections. Then center the tubing over the crimped connector and shrink it with a heat gun or by playing a flame beneath it. Be sure there are no explosive fumes in the bilge!
Connect to the battery
When you turn the power off to leave the boat unattended, you don't want to turn off the bilge pump. Connect an automatic bilge pump directly to the battery, not through the distribution panel.
Fuse the positive side
It is essential to have a fuse in the positive wire as close to the battery as possible. Some switch panels (see below) include a fuse. Otherwise join an in-line fuse holder to the battery end of the positive wire using a crimp butt connector.
Install terminal fittings
Do not strip the ends of the supply wires and loop them beneath the battery terminal wing nuts. Install crimp-on ring terminals the proper size to fit the threaded posts on your battery. Use a copper washer-not steel-between the wing nut and the ring terminal.
Three-way switch
If your bilge pump has a separate float switch, you may want to wire it to a three way switch that allows you to select automatic, on, or off. Be sure to support all wire runs at least every 18 inches using cable clamps or ties.
Two pumps
A bilge pump big enough to deal with a real emergency will do a poor job of keeping the bilge dry because the water in the discharge hose drains back into the bilge when the pump shuts off. And a big pump requires a big hose.
The ideal bilge pump arrangement is a small (400 gph) automatic bilge pump mounted in the sump to dispense with rain and shaft-gland leakage, combined with a high capacity pump (3,500 gph) mounted higher to deal with more serious ingress.
Stepping the discharge hose from the small pump down to 1/2-inch minimizes the backflow from the hose when the pump cycles, maintaining a dryer bilge. The large pump can be wired to a float switch if you prefer, but I think a manual switch makes more sense. An added advantage of this bilge pump configuration is that the high-capacity pump sits high and dry, extending its life indefinitely.
The ABYC Wire Size Table, a more complete explanation of the two-pump system, and other information about bilge pump installations can be found in This Old Boat by Don Casey.
Go to BoatTECH Guides : Go to Don Casey Library
01-03-2009, 05:30 AM
#3
I'm not quite sure why you would not want both pumps to have an auto Switch? Might be a good idea to make one or both pumps setup on a manual "on" switch ...If you have the 1100"s with the internal switch they have a brown wire for the Auto feed and a Brown/White wire for manual operation. I lost a 1.25" hose between the sea pump and the motor at WOT and it pumped a bunch of water in a hurry into the bilge.....I was glad both pumps came on!
Where are you pumps mounted? In my Formula they are mounted on a pad forward in the engine room ...So water has to build from the transom up to the Bulkhead before the pumps come on ... I added a "water puppy" type pump on a switch. I ran the suction hose is down in the Vee at the rear of the boat ....right where the drain plug is .....I can flip it on from time to time and get every last drop of water out ....The water puppys are reversable so if It picks up something and gets plugged I can reverse it and blow the obstruction out ....m
Where are you pumps mounted? In my Formula they are mounted on a pad forward in the engine room ...So water has to build from the transom up to the Bulkhead before the pumps come on ... I added a "water puppy" type pump on a switch. I ran the suction hose is down in the Vee at the rear of the boat ....right where the drain plug is .....I can flip it on from time to time and get every last drop of water out ....The water puppys are reversable so if It picks up something and gets plugged I can reverse it and blow the obstruction out ....m
Last edited by offthefront; 01-03-2009 at 05:34 AM.
01-03-2009, 08:33 AM
#4
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Platinum MemberThread Starter
Daredevil, makes a lot of sense to me. I have time to kill waiting for other parts of the boat to get ready so I am doing too much thinking.
Orthos1, whoever built my boat did most things on your list. The two different sized pumps makes sense.
Offthefront, the water puppy idea sounds good as I always have just a little water in the bilge that just can't go and couldn't figure out how to get rid of it.
Thanks for the info guys.
So I am thinking a total of about 2200 gph should be enough for my boat. What do most of your boats run?
Orthos1, whoever built my boat did most things on your list. The two different sized pumps makes sense.
Offthefront, the water puppy idea sounds good as I always have just a little water in the bilge that just can't go and couldn't figure out how to get rid of it.
Thanks for the info guys.
So I am thinking a total of about 2200 gph should be enough for my boat. What do most of your boats run?
