Help Needed with Bilge Pump (Again)

[gpd955]

After months of dealing with my bilge pump, I am seeking some advice.

PO had a Rule 1200 with about 3 ft of 1 1/8" bilge hose scaled down to 3/4" heavy duty hose that led to the through hull which is port side just below the transom. I could not get the pump to work and since it did pump water when I disconnected the hose, figured the hose was clogged somewhere along the line. I removed the entire hose and replaced it using the same configuration. There was no clog so I used my previous firefighting experience and though maybe with the friction loss in the 1 1/8" hose there was not enough pressure to push the water through the smaller diameter hose. So I shortened the larger hose to about 6". Still no water coming out of the through hull.

Then the pump stopped working, so I replaced it with a RuleMate 1500. Filled the bilge.....still no water coming out. I disconected the existing hose set up and put about 15 ft of 1 1/8" hose and brouhgt it up to the cockpit. The water came up to about where the cockpit seats are but there was not enough pressure to get the water high enough to go overboard. As I lowered the hose back into the boat, I found that at about sink level, a small amount of water would come out. When the hose was back at the level of the bilge, great flow!

So the problem obviously is the pump not having the strength to pump uphill.

Are there better pumps out there??
Are there any other ways to get this to work??
Can someone pleeeease give me some suggestions on how to get the pump to do its job??!!??!!

Sorry about the long message!!

Jack Manning
S/V Victim of Fate
Atlantic City, NJ

[Gene T]

You can find out the pump specs on line I believe and determine what it should be able to do. But it sounds like either the pump is bad or the installation is bad. Is water into the pump unrestricted? Is the wiring adequate? Undersized wiring will reduce pump output dramatically. Check the voltage at the pump. Pumps should be wired directly to a battery with an in-line fuse. Is the pump impeller in good shape? Look for broken fins. NEVER neck down output lines. Low pressure lines must offer the least back pressure.

Good luck troubleshooting.

[sailingdog]

Where is the pump located in relation to the bilge and the through-hull it drains out?

Again, I'd repeat what Gene T said: Never neck down output lines on a pump. Low pressure lines must offer the least back pressure. This is especially true if you're using a centrifugal pump of any sort, which doesn't tolerate any back pressure at all well.

[gpd955]

The pump is dead center of the boat and the hose runs aft for about 2 feet and gradually curved port for about 1 foot, goes up about 3 feet in about a 2 foot run, back down about 6" to the through hull.

The pump is brand new and as I said when I disconnect the hose the flow is great from the pump so it is definitely a hose size/height issue.

I will pull the heavy duty hose though and switch to the 1 1/8" bilge hose and see what happens at the though hull level.

[pigslo]

Sailingdog says....Never neck down output lines on a pump. Low pressure lines must offer the least back pressure

I will disagree with you both on that score as the bigger diameter pumps allow too much water to backflow into the bilge when the pump shuts off. Get a bigger pump or a different kind that has a higher head presure.

[hellosailor]

Jack, the Rule-Mate 1500 appears to be an automatic version of their #2 pump. Oddly not well documented on their web site. And even more oddly, Rule shows the pump as 4.8A@12V and 7A@13.6V, which sounds like they got the numbers reversed. (Motors draw MORE amperage as the voltage goes down, not less.)

So first, assuming it needs 7A at battery voltage, and the wire run is 30 feet from the battery, that would require a nominal 60-foot run adequately sized for 7A service. My wire gauge charts show 5A service requires 10AWG and 10A service requires 6AWG, so you might actually need 8AWG wire to supply the power that pump draws! And that's assuming all crimps are solid and clean as well.

First thing to check: With a voltmeter, when the pump is turned on and running (disconnect the discharge hose) do you still get 12V at the pump while the engine is not running? How does the voltage at the pump (or as close as you can get) compare to at the battery?

Second thing, the head (lift) rating for the pump. It seems to be rated at 1200GPH with a 3.3 FOOT lift, and drops to 800GPH with a 6.7 foot lift--and those are both with the full 1-1/8" hose. If you've got a four foot lift, or five foot lift, and you are reducing the hose size, I'd still expect it to pump 100-200GPH though the smaller hose. That it is not pumping AT ALL might indicate the impeller is slipping on the shaft, or that the motor (as above) isn't getting enough power to turn against the extra restriction.

But I wouldn't reduce the hose size at all, if you're going to do that you might as well just buy a pump that is half the price and designed to use that little hose! Use the 1500 as a damage control pump, and then add in a small--very small-- pump using a very small hose as the "squeegee" pump, which sucks the very bottom of the bilge. Move the 1500 up an inch or so above the bottom, so it isn't used until and unless there's really a need to move water, and that way you don't have to worry about the "big" slug of water coming back down the hose when it cycles.

Yes, using two pumps really is the simplest way to accomplish this, without compromising the capacity of the big pump, and without leaving water in the bilge.

[sailingdog]

Originally Posted by pigslo

Sailingdog says....Never neck down output lines on a pump. Low pressure lines must offer the least back pressure

I will disagree with you both on that score as the bigger diameter pumps allow too much water to backflow into the bilge when the pump shuts off. Get a bigger pump or a different kind that has a higher head presure.

Yes, bigger diameter pumps allow too much water to backflow, but if the pump has a 1-1/8" output hose, you shouldn't neck it down to fit the through hull. You should install the proper size through hull for it. You really do need to have at least two bilge pumps. A small one that keeps the bilge dry, and a bigger capacity one to drain the bilge when the water level is faster than the little one can handle. For instance, the bigger one would switch on if you swap out the speed transducer and water gets in the bilge. But for the leaks associated with the stuffing box, the small pump, with a much smaller diameter hose, should suffice.

[Gene T]

hellosailor said (Motors draw MORE amperage as the voltage goes down, not less.)

Not true, with less voltage the DC motor will just run slower and pump less. AC works the opposite as it is a constant power consumer.

[Gene T]

two pumps are the best setup for almost everyone. The float switch for the smaller pump should be mounted lower than the large one.

[pigslo]

I have a small pump that has a chip in it that senses water on the impellor. It comes on to test every 2 minutes unless no water is sensed and then goes to every 10 minutes. This on a small hose with a big pump behind is the best arangement.