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Shortman 12-06-2008 10:18 AM

Bilge pump preference
 
I have a Rule non-automatic 1000 GPH with a standard float switch. Has generally worked OK, with some problem in cavitation when heeling.
What do you have, what do you like? Automatic w/integral switch? External switch, float, electronic? Brands?

sailhog 12-06-2008 10:27 AM

I like a remote switch if only to keep the pump in more protected place. Mine is a $130 Jabsco and it seems to work fine.

sailingdog 12-06-2008 10:48 AM

It really depends on what you're going to be using said bilge pump for. The small ones with an integrated float switch are great for maintenance bilge pumps, where they just take care of the day-to-day drips and leaks into the bilge, but for an emergency bilge pump, you'd probably want it with an external float switch and much higher capacity.

Rule, Jabsco, etc. are all pretty decent, but just remember that the pump's GPH rating is usually for ZERO LIFT.

MedSailor 12-06-2008 09:37 PM

I'm a recovering wooden boat owner so I know a lot about bilge pumps. ;-)

I have to say that without reservation I recommend rule. I tried a couple other brands and under my hard use/abuse they all died eventually. The two rules that came with the boat (1500 and 2000) were still going strong after 5 years of ABUSE. Once I came back from a week long trip and found it running dry with a stuck float switch. It was fine. They both saved the boat more times than I am willing to admit.

Switches are another issue. I probably went through 15 or so. The only one I really liked was the electronic switch by Johnson called the ultima. That and the old type that have a metal ball that you can hear roll from end to end when the switch is lifted. All the rest crapped out in no time.

Remember always have 2 (or more) electric bilge pumps wired to different batteries.

Medsailor

Maine Sail 12-06-2008 09:53 PM

Don't forget high water alarms. I use three WatchDog Water Alarms (LINK) alarms on my boat and they are very, very loud similar to a smoke detector and they can be heard over the noise of the engine! I have one three inches off the bottom of the bilge, one in the engine compartment and one in the head.

As far as bilge pumps go I think we need to be very careful taking any centrifugal pump at face value. Having two large pumps a wise idea with centrifugals!

Flow rates, as rated by bilge pump makers, can be quite misleading. They should serve only as a rough guide of a pumps "best case" capacity compared to others of similar design.

Bilge pump capacity is usually rated as “open flow” or what's called “open bucket” rate. This means the figures account for no, nada, zero vertical lift and also no discharge hose friction, radiused bends or discharge outlet restriction.

Actual flow rates, under real operating conditions, can be drastically lower. Water must be lifted up and out of the bilge and then be pushed through lengths of hose to the discharge point. This resistance is called head. Head pressure is basically the weight of the water and the frictional resistance of the hose, bends and outlet. Most centrifugal pumps, like the ones made by Rule or Johnson Pumps, have large internal tolerances to allow passage of bilge crap, so their flow rate decreases dramatically with increases in head. Unlike a vane pump, which would be less affected by head loss, the pumps rotor or impeller does not come in direct contact with the pumps walls. Impeller/vane pumps and diaphragm pumps are less affected by head pressure than a centrifugal pump is and they may actually be more effective despite a lower "labeled" GPH rating. Some of the vane/impeller pumps can handle 60+ feet of head pressure with ease. Because of the large tolerances in centrifugal pumps it can lead to, and create, cavitation if the head pressure is extreme enough.

I'm sure many of us have seen the bilge pump kick on and then not actually suck any water but instead just create noise and bubbles in the bilge. This can usually be eliminated by removing those ridiculous head boosting flow checks and the crappy corrugated bilge hose and replacing it with smooth walled hose..

The output of many centrifugal bilge pumps can diminish by as much as half with only a few feet of head and can stop entirely at between 13 and 20 feet, depending on the size of the bilge pump. Remember head is not just the peak height/lift of the hose it is the friction, height, bends and fitting restrictions all added together.

Another serious consideration is voltage. What is your pump rated at? Is it 14.2 volts or 12 volts. This will and can make a difference as the pumps motor increases and decreases output based on voltage.

There have been a few tests like the ones conducted by West Marine. They rated pumps based on voltage and head pressure. Most manufacturers ratings (open bucket / no head ratings) were off between 10-50%. the output on average was reduce by about
5% for every foot of head pressure. With voltage the drops from 13.6 volts to 12.2 volts were another 15-30% off on top of the head pressure loss. So your 800 GPH centrifugal pump may not even deliver 1/3 of that rating in a real word situation..

I guess what I'm getting at is this; unless you have a "monster truck" grade bilge system, do not count on anywhere near the face value rated capacity from your bilge pump.

Some other things to consider:

- Use smooth walled discharge hose as it has significantly less head resistance than does corrugated.

- If the discharge outlet is close to the waterline you must use a high loop in the discharge hose to prevent siphoning. It is advised to add a siphon break at the highest point to ensure it won't siphon. Even with a high loop a bilge pump can still siphon without a siphon break. I have been on more than one boat that self siphoned when under sail and power.

- Do not succumb to the temptation of using a "check valve" with a centrifugal pump. If you have 5' of height, in a 1" hose, the pump will more likely than not cavitate before it can throw open that check valve with that standing water behind it..

Disclaimer: Many years ago I used to sell a line of submersible pumps to the plumbing and well supply wholesale distribution channels.

Quickstep192 12-06-2008 10:10 PM

I have a Rule "automated" pump in a boat that collects a lot of rain water. It has an internal sensor that makes the pump come on when the water level rises and keeps it running 20 seconds after the water level drops so it cycles less. I don't like seperate float switches as they can get pinned under someting that prevents them from coming on, or get something stuck under them so the pump never goes off and leaves you with a dead battery. On my old wooden boat, I had Lovett pumps that worked hard, and never failed. If I had room, they'd probably be my first choice.

Pamlicotraveler 12-07-2008 05:58 PM

We have the Ultra Sr. pumpswitch by Ultra Safety Systems, and from everything I have heard or experienced they are bullet proof. A bilge pump is pretty important of course and the Ultra Sr. has a High water alarm. Our is sent way down into the bilge.

nightowle 12-09-2008 05:56 AM

pump placement question for Mainsail???
 
QUOTE:

- If the discharge outlet is close to the waterline you must use a high loop in the discharge hose to prevent siphoning. It is advised to add a siphon break at the highest point to ensure it won't siphon. Even with a high loop a bilge pump can still siphon without a siphon break. I have been on more than one boat that self siphoned when under sail and power.

- Do not succumb to the temptation of using a "check valve" with a centrifugal pump. If you have 5' of height, in a 1" hose, the pump will more likely than not cavitate before it can throw open that check valve with that standing water behind it..

Disclaimer: Many years ago I used to sell a line of submersible pumps to the plumbing and well supply wholesale distribution channels.[/QUOTE]

Mainsail: I wanted to ask you about having the discharge close to the waterline. I will be installing a Whale pump that is designed for shallow bilges. I'd like to 't' into the sink discharge through hull which is only about 4 feet from where the pump will be and I'll avoid having to create another hull opening. Will I still need to put high loop in the discharge hose even if the pump has a check valve?

Thanks

Shortman 12-09-2008 07:35 AM

yes, high loop
 
I'll chime in on the question to Maine Sail. Yes high loop, because if the check valve fails, you gonna have a wet boat.
Practical Sailors sister publication, Power Boat Reports, tested a bunch of pumps and reported data on much of what Maine Sail is talking about 20 Electric Bilge Pumps Tested
I do have a check valve because the discharge line is Tee'd into the shower sump line and then the single line has a vented loop. I will probably give it it's own vented loop then tee the lines right before the thru hull.
One of my main interests in the original question is the switching. Integral within the pumps certainly seems less to maintain. The electronic ones would seem to offer better reliability.

Joesaila 12-09-2008 07:52 AM

Quote:

Originally Posted by Maine Sail (Post 413057)
Don't forget high water alarms. WatchDog Water Alarms (LINK)[/URL] alarms on my boat and they are very, very loud similar to a smoke detector and they can be heard over the noise of the engine! I have one three inches off the bottom of the bilge, one in the engine compartment and one in the head.

Thanks for the tip Maine Sail! I didn't know about water alarms and will get one for the boat and my basement. Inexpensive too via Home Depot. And the smooth hose makes sense too.

Thanks Pamlicotraveler for the tip re Ultra Safety Systems. I use Rule but will grab one of those switches! ...good post!


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