Installing Bilge Pumps

[off-the-grid]

sarafina - damn you for hijacking my thread!

All this check valve, vent, etc. that we're getting into here.
What about my situation?

Gord - Heeling! What's that? I'm a cat.
The spot where I was talking about routing my hoses, the hose would end high inside the tranzom stairs (aka the rudder compartment) which has drains in the bottom.

If the ends of those hoses make it under water, the boat is already sinking. The access panel is low enough on the transom that even folowing seas won't get to those hoses.

Pblais - yes the cockpot has it's own drains, and it would be impossible for water there to get in contact with my bilge hoses.

[GordMay]

Originally Posted by grunzster

Gord - Heeling! What's that? I'm a cat.
The spot where I was talking about routing my hoses, the hose would end high inside the tranzom stairs (aka the rudder compartment) which has drains in the bottom.
If the ends of those hoses make it under water, the boat is already sinking. The access panel is low enough on the transom that even folowing seas won't get to those hoses.

If backflow (downflow) is practically impossible, don't worry about it.

[sarafina]

aw don't grunz.... admit it, some of this has been helpful for you too!

Here's what I would say now to your initial questions;

Wires the bilge pump and the float switch to a little panel made for this purpose, which is then wired wither directly into the battery, or on a more elegant system, wired into a busbar between the batteries and the main switch.

We are going with that busbar because it allows you to wire in the bilge pump and the stereo before the main, so that when you leave the boat and want to turn off the 12 volt system you can just hit the main switch without disabling the bilge pump or loosing your channel and clock settings on the stereo system.

The little panel I refer to has a rocker switch on it that allows you to leave the bilge in on or off or auto.

Now that I am done dealing with some triage that came up on our little hole in the water I am back on the bilge plan.

I scored a rule 1100 and a float switch this weekend at a swap meet, both new for $15 total. I am a happy girl.

Still need to resolve the output issues, but at least the other end of it is coming into place. The 1100 will be my portable back up used in the shower. I will still need the larger pump for the permanent install in the bilge, on that little rocker panel. Need to order the hand pump replacement. We are close to running wiring now install should follow soon after that. I just keep looking at the hull and trying to decide where I want to run the output. Man I hate cuttin holes in boats... just goes against my nature I guess ; -)

[sarafina]

something simple is available or you can do a cool one like this!

[FrankZ]

I like that switch panel Sara.

Using something like that one would need to be sure it is rated appropriately, both for each switch and overall panel rating. Have a look at the draw of a Rule 8000, yikes. It might be too heavy for something like that.

[Strygaldwir]

For the catamarans, the issue may be run length of power supply lines for a central panel/switch. Running our port, aft engine room pump to one central panel on the starboard mid breaker panel is a LONG way(about a 90 foot cable run. Got to count both to and from) , thus the switch directly to battery that is 6 inches away. Mid cabin is still a long way (50 feet, but... no other convenient place to mount the switch).

As indicated, we have six bilge pumps. Aft engine room, Mid hull and forward hull. The engine rooms are behind a water proof bulkhead until the water rises about 1.5 feet. The forward hull section is not behind a water tight bulkhead. It will drain to the mid hull pump, or act as an additional backup if the water rises above about 1 foot. Under most circumstances I'd think a catamaran should have a minimum of two in each hull. Maybe more for the larger cats.

We have built in manual pumps. But, I think I read the majority of sinking's occur while the boat is tied to the dock. In essence there is no one aboard to notice or operate the manual pump when it is sinking.

It is my intent to buy a high capacity Rule pump with long power lines and exhaust hose. Not so much for my boat, but to come to the assistance of another boat that may not be set up as well. Oh, okay, it is for my boat too! Can't hurt to have it!

[Solitude]

Originally Posted by sarafina

heh... the smaller the vessel the bigger the pump huh?

*evil grin*

Here is an article.

http://www.captfklanier.com/articles/art2.htm

[sarafina]

ok all joking aside, that one got copied and pasted into my digital library. Thank you!

[CharlieJ]

When contemplating bilge pump sizes; remember that the published pumping capacity is against zero head; no bends, no elbows, no corrugations, and no vertical lift.

That said, you might be interested in the flooding rate for a 3/4" diameter hole at various depths below the water line:

1' 11 gpm
2' 16 gpm
3' 19 gpm
4' 22 gpm
5' 25 gpm

It is much scarier for a 2" diameter hole:

1' 79 gpm
2' 111 gpm
3' 136 gpm
4' 157 gpm
5' 176 gpm
6' 193 gpm

With these numbers the old adage about a scared man with a bucket goes right out the door with all of those non-SOLAS approved flares and smokes!!

And remember, you need to provide the highest quality power possible to the bilge pumps. The ABYC requires <3% voltage drop. That voltage drop is measured from the battery terminals, through interconnecting conductors, panel boards, etc. to the bilge pump. Most bilge pump and all float switch leads are AWG 12 or less. So you are going to pick up a pretty large voltage drop, with a big pump, in the last 4 or 5 feet. I typically have to run AWG 8 to the bilge pump terminal strip to ensure that the voltage drop from the battery to the pump is less than 3%.

As far as the over current protection (OCPD, fuses or circuit breakers); the pump manufacturer is required to provide the OCPD size recommendation in the pump literature. This is to ensure against the locked rotor failure that has been discussed in this forum before.

Finally, consider the lowly Auto-Off-Manual bilge pump control switch. Many of them have a spring return for the Manual position. It is my opinion that this is a poor design. Consider the scenario that includes failure of the float switch. The only way you can make that pump operate is to stand and hold the switch in the Manual position. I would personally prefer turning the bilge pump on with a non-return switch, and use my time to go find the source of the water. As you can see from the flooding rates above, any appreciable flooding rate will simply overwhelm your pump(s) so finding and stopping the source of the flooding is job #1. (Oh, and I don't like the Off position either.)

As you can tell, I consider bilge pumps a big deal.

[sarafina]

me too Charlie. tsunami had ONLY one little hand pump like 12" long when we got her in June. That's it. I was appaled. My mispent youth was spent for a large part of the summer on the California delta in old wooden boats. Where my grandfather, my dad and then myself were hysterical about bilge pump function, because the dratted things could sink overnight if the pump stopped working on a night there was a problem. We never lost a boat but knew folks who did because their float switches were gummed up and failed when a leak sprang and water started coming on when no one was around. And plenty of times I stuck our spare into the cabin of a neighbors boat to keep the water below the gunels, until he could get down and fix his pump. again.

We now have the original little pump, which I must admit is cleverly positioned to get EVERY last drop down there, a large manual, and one electric rule1100 with float. That is on a fused switch all it's own, straight to the battery. We plan on another electric as soon as I can find another good used one and will install it a bit higher as a back up, not on a float, so that when it meets water it just pumps.

[GordMay]

Originally Posted by CharlieJ

When contemplating bilge pump sizes; remember that the published pumping capacity is against zero head; no bends, no elbows, no corrugations, and no vertical lift.

That said, you might be interested in the flooding rate for a 3/4" diameter hole at various depths below the water line:

1' 11 gpm
2' 16 gpm
3' 19 gpm
4' 22 gpm
5' 25 gpm

It is much scarier for a 2" diameter hole:

1' 79 gpm
2' 111 gpm
3' 136 gpm
4' 157 gpm
5' 176 gpm
6' 193 gpm

With these numbers the old adage about a scared man with a bucket goes right out the door with all of those non-SOLAS approved flares and smokes!!

And remember, you need to provide the highest quality power possible to the bilge pumps. The ABYC requires <3% voltage drop. That voltage drop is measured from the battery terminals, through interconnecting conductors, panel boards, etc. to the bilge pump. Most bilge pump and all float switch leads are AWG 12 or less. So you are going to pick up a pretty large voltage drop, with a big pump, in the last 4 or 5 feet. I typically have to run AWG 8 to the bilge pump terminal strip to ensure that the voltage drop from the battery to the pump is less than 3%.

As far as the over current protection (OCPD, fuses or circuit breakers); the pump manufacturer is required to provide the OCPD size recommendation in the pump literature. This is to ensure against the locked rotor failure that has been discussed in this forum before.

Finally, consider the lowly Auto-Off-Manual bilge pump control switch. Many of them have a spring return for the Manual position. It is my opinion that this is a poor design. Consider the scenario that includes failure of the float switch. The only way you can make that pump operate is to stand and hold the switch in the Manual position. I would personally prefer turning the bilge pump on with a non-return switch, and use my time to go find the source of the water. As you can see from the flooding rates above, any appreciable flooding rate will simply overwhelm your pump(s) so finding and stopping the source of the flooding is job #1. (Oh, and I don't like the Off position either.)

As you can tell, I consider bilge pumps a big deal.

Right on!

The published rating, to which Charlie aludes (published pumping capacity is against zero head; no bends, no elbows, no corrugations, and no vertical lift), are almost certainly calculated at > 13 Volts applied to the pump.

If you examine the 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

It should be apparent that the smaller the boat, the larger the pump required to overcome flooding (resist “pounds per inch immersion”) .

[knottybuoyz]

I have a tendency to over engineer everything. I think I might have nailed this one though. This is a 4000 GPH pump, what I refer to as a "Crash Pump".



This'll be located in the keel mated to the Rule-a-matic 20A switch.



The main battery bank will be less than 16" above the pump & switch. The 2" outflow from the pump will run to a thru-hull 18" above the water line and have a loop up to the gunnel with a max lift of about 4'.

Normal de-watering duties will be handled by a pair of Rule 800 GPH & Water Witch solid state switch. Scuppers in the fwd cabin will also run into the shower sump which houses a 1100 GPH Johnson Pump & switch.

I think I've got it covered. :-)

Anybody looking for a large pump I got my 4000 GPH Rule on e-Bay for $100 which I think is a decent price. E-Bay item #160370865354.

[CharlieJ]

knotty-
Is your crash pump located so it is not sitting in normal bilge water? If not, it is my opinion that it should be. I do not use the Rule switches but if you position yours above the normal bilge water level it will not see water unless you have some real flooding, I guess it is ok.

You did not mention a bilge high water alarm...it is my opinion that they are mandatory on any boat with a cabin. How many stories have you heard about the off watch rolling out of the bunk and stepping ankle deep in flooding water???!!!! and always at 0 dark thirty!~!!!

Yup...bilge pumping systems are a real big deal.

[cal40john]

Originally Posted by GordMay

Right on!

The published rating, to which Charlie aludes (published pumping capacity is against zero head; no bends, no elbows, no corrugations, and no vertical lift), are almost certainly calculated at > 13 Volts applied to the pump.

If you examine the 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

It should be apparent that the smaller the boat, the larger the pump required to overcome flooding (resist “pounds per inch immersion”) .

I still say you've got the equation wrong Gord. The d is squared.

If you use d^2 instead of d your equation gives the values in the OP's table, and other tables I've seen.

post #3
http://www.cruisersforum.com/forums/...read-6547.html

John

[GordMay]

Originally Posted by cal40john

I still say you've got the equation wrong Gord. The d is squared.

If you use d^2 instead of d your equation gives the values in the OP's table, and other tables I've seen.

post #3
http://www.cruisersforum.com/forums/...read-6547.html

John

And you'd be just as right, this time, as last.
THANKS!

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