Rule 2000 not lifting

[Celestialsailor]

Originally Posted by stormalong

Very nice. Is that big piece of sheet metal stainless?

Yes...The former one was aluminum and eaten away. From the sole to the bottom of the bilge is over 3 feet. The unit hangs on one of the floors. It makes it easy to service.

[boatpoker]

Does anyone know how to calculate the difference in flow rate between corrugated hose and smooth hose due to friction loss ?

[stormalong]

Originally Posted by boatpoker

Does anyone know how to calculate the difference in flow rate between corrugated hose and smooth hose due to friction loss ?

No, but the height the water is lifted (head) is far more important. There are different degrees of corrugation so the answer would have to be: "it depends". Many spiral plastic or wire reinforced hoses are actually very smooth on the inside.

[Celestialsailor]

Ok...Update and I could use some suggestions. I rewired the whole system with #10 tinned wire. All connections to the bilge pump and float switch are connected wire to wire and soldered, then wrapped in rubber tape. I have almost no voltage drop since I used #10...that includes under load also. I tee'd into a 1 1/2" scupper drain...that was a mistake. It backed up to the deck but pumped very well. So I will have to have a designated thru-hull for the bilge pump.
The volume of the water in the 15ft. of 1 1/8" hose, back drains into the bilge. The float switch becomes reactivated and therefore cycles on and off. I have heard not to put a check valve at the pump. Any thoughts on that?
I also noticed when I shut the system down and manually pump the bilge and then turn the electric bilge pump on, it cavitates and will not pump. Any thoughts?

[stormalong]

Originally Posted by Celestialsailor

Ok...Update and I could use some suggestions. I rewired the whole system with #10 tinned wire. All connections to the bilge pump and float switch are connected wire to wire and soldered, then wrapped in rubber tape. I have almost no voltage drop since I used #10...that includes under load also. I tee'd into a 1 1/2" scupper drain...that was a mistake. It backed up to the deck but pumped very well. So I will have to have a designated thru-hull for the bilge pump.
The volume of the water in the 15ft. of 1 1/8" hose, back drains into the bilge. The float switch becomes reactivated and therefore cycles on and off. I have heard not to put a check valve at the pump. Any thoughts on that?
I also noticed when I shut the system down and manually pump the bilge and then turn the electric bilge pump on, it cavitates and will not pump. Any thoughts?

I have a check valve. Not the ideal solution perhaps but it works - most of the time. My lift (head) is about six feet. If there is air below the check valve it will not push the check valve open against the water pressure. So, whenever I have serviced the pump I need to quick cycle the pump until it forces it's way through the check valve. I also have to have some water in the bilge so that the pump always pumps water and not air.

Some people suggest a pin hole above the pump vane so that air can escape. I have not done that - could not see a practical way to do that on my pump (Rule 1500).

Another alternative would be a positive displacement pump instead of a vane pump. Positive displacement pumps have valves built in - necessary for this kind of pump to function.

So, I live with the problem and very occasionally have to deal with it. I do have a high bilge water alarm about a foot above the pump to tell me when I have a problem. It is a deep sump so there is plenty of space above the alarm float switch. My shower drains into the bilge so it is common to get water in the bilge.

Celestial sailor: You say that the pump hose is fifteen feet. The lift (head) determines how much pressure that translates into. If it is much more than the six feet mine has I doubt a vane type pump would provide enough force to open the check valve. The quickest fix I can think of is use a check valve and to position the float switch high enough that a couple of inches of water stay in the bilge when the pump switches off. I know some people don't like any water in their bilge so this may be unacceptable to you. In which case I think your best choice is a positive displacement pump. I don't mind the water deep in the sump because it is usually shower water or the water that comes down inside the mast when it rains.

[Bowdrie]

The pump is doing what is called "short cycling", you have to raise the float switch due to so much water draining back.
When you pump manually you get the water level low enough that the Rule pump sucks in some air.
It's a centrifugal pump, it will never leave a dry bilge, and it will only pump when the water level is somewhat above all those slots around its base.
After all, it's a "submersible" pump, it pumps when its inlet slots are submerged.
Reducing the rise and run is key to good operation of ANY centrifugal pump.

[donradcliffe]

A check valve will make the cavitation problem worse.

If you want a reliable bilge pump system that you can leave unattended and will keep the bilge dry, use a diaphragm type pump.

[Celestialsailor]

Originally Posted by Bowdrie

The pump is doing what is called "short cycling", you have to raise the float switch due to so much water draining back.
When you pump manually you get the water level low enough that the Rule pump sucks in some air.
It's a centrifugal pump, it will never leave a dry bilge, and it will only pump when the water level is somewhat above all those slots around its base.
After all, it's a "submersible" pump, it pumps when its inlet slots are submerged.
Reducing the rise and run is key to good operation of ANY centrifugal pump.

I would have to disagree with your take on the float switch no matter where that float switch is located, it will shut off when it reaches it's normally closed switch position and the same amount of water, no matter where the float is positioned (high or low), the same volume of water will drain back into the bilge cubby area and reactive it.

[Celestialsailor]

Originally Posted by stormalong

I have a check valve. Not the ideal solution perhaps but it works - most of the time. My lift (head) is about six feet. If there is air below the check valve it will not push the check valve open against the water pressure. So, whenever I have serviced the pump I need to quick cycle the pump until it forces it's way through the check valve. I also have to have some water in the bilge so that the pump always pumps water and not air.

Some people suggest a pin hole above the pump vane so that air can escape. I have not done that - could not see a practical way to do that on my pump (Rule 1500).

Another alternative would be a positive displacement pump instead of a vane pump. Positive displacement pumps have valves built in - necessary for this kind of pump to function.

So, I live with the problem and very occasionally have to deal with it. I do have a high bilge water alarm about a foot above the pump to tell me when I have a problem. It is a deep sump so there is plenty of space above the alarm float switch. My shower drains into the bilge so it is common to get water in the bilge.

Celestial sailor: You say that the pump hose is fifteen feet. The lift (head) determines how much pressure that translates into. If it is much more than the six feet mine has I doubt a vane type pump would provide enough force to open the check valve. The quickest fix I can think of is use a check valve and to position the float switch high enough that a couple of inches of water stay in the bilge when the pump switches off. I know some people don't like any water in their bilge so this may be unacceptable to you. In which case I think your best choice is a positive displacement pump. I don't mind the water deep in the sump because it is usually shower water or the water that comes down inside the mast when it rains.

The entire run is 15ft. long. The rise is 6'6". I am agreeing with you on the check valve and I like your idea of the additional alarm. The only reason it cavitated is because I used the manual pump to remove the last little bit of water. The manual pump has a check system and removes water very efficiently. I think I will raise the suction hose up a few inches to leave enough water for the auto bilge pump to stay submerged.

[Celestialsailor]

Originally Posted by donradcliffe

A check valve will make the cavitation problem worse.

If you want a reliable bilge pump system that you can leave unattended and will keep the bilge dry, use a diaphragm type pump.

They have their problems also, if you're talking about the belt driven ones. I sold four dead ones as parts at a marine swap meet last year.

[Jammer]

If possible your best bet is probably to put a vented loop close to the pump and run the hose downward from there to the thru-hull. Not always feasible.

Otherwise for nuisance water a diaphragm pump may indeed be your best choice. That is what I have on my boat for both the bilge and the shower sump. They are the four-diaphragm rotary type, not the ones with the belt. No bilge pump lasts for ever. The belt-driven ones are repairable and expensive so you are best off repairing them from time to time. The rotary head ones are somewhat less repairable and are "serviced as an assembly."

[rslifkin]

I agree with the diaphragm pump suggestion. A small centrifugal won't do well at lifting high enough, but a diaphragm pump will. Let that take care of small bits of water (no drainback and ability to suck the bilge dry), then let the big centrifugal pump handle any large amounts of water that may occur.

[Bowdrie]

Originally Posted by Celestialsailor

I would have to disagree with your take on the float switch

You're right, it would need one of those adjustable float jobs where you can adjust the differential.

[Celestialsailor]

This is all great input and I wish someone had brought the topic up earlier. I would have bought a diaphram pump. I'll try a few other changes. I'll let you know what I find. My other boats, although some had deep bilges, had nothing as deep as this one.

[rslifkin]

Originally Posted by Celestialsailor

This is all great input and I wish someone had brought the topic up earlier. I would have bought a diaphram pump. I'll try a few other changes. I'll let you know what I find. My other boats, although some had deep bilges, had nothing as deep as this one.

The diaphragm pump would be in addition to the big Rule, not instead of. So you'd want/need what you've already got anyway, just possibly with a change to the height of the float switch for it.