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Author Topic:   Bilge Pump
breakaway posted 11-13-2012 04:14 PM ET (US)   Profile for breakaway   Send Email to breakaway  
I have a 1996 Montauk. I am looking to replace my Rule bilge pump which died after many years. Rule has discontinued the model pump I had. Does anyone have a recommendation for a new automatic bilge pump with a built in float switch that will fit into the very small bilge area on a Montauk?


L H G posted 11-13-2012 05:58 PM ET (US)     Profile for L H G    
I'm sure you will get many ideas, but here is how I did mine, using a Rule "chip sensing" auto 500 GPH pump. The white cord wrapped around the pump is for the dash switch on-off override, with the orange wire nut connections, caulk filled. All is concealed under the teak sump cover.
Black smooth wall discharge tube is bundled with the engine rigging and terminates in a 3/4" plastic "L" fitting for discharge over the transom. Scan_Pic0008.jpg.html?sort=6&o=45#/user/lgoltz/media/Montauk%2017/ Scan_Pic0008.jpg.html?sort=6&o=45&_suid=135284692362006452278802626674

jharrell posted 11-13-2012 09:13 PM ET (US)     Profile for jharrell    
I keep looking at the Rule-Mate pumps, specifically the 1100gph, wondering if they will fit in the Montauks bilge: ProductDisplay?catalogId=10001&storeId=11151&productId=34062&langId=-1#. UKL8rIc701I

jimh posted 11-13-2012 09:18 PM ET (US)     Profile for jimh  Send Email to jimh     
Here is some advice that is the complete opposite of Larry's:

Get rid of those submersible pumps with centrifugal mechanisms. They're not very good pumps. They are not very expensive. There are problems with them.

First problem: they will never get the sump dry. They will always leave water in the sump.

Second problem: they can't lift water very far. The output drops off like it went over a cliff if you ask the pump to lift the output water more than a few inches.

Third problem: who puts electrical pumps under water in wet places?

Fourth problem: who uses wire nuts on a boat?

I am considering refitting with a real pump, not a toy. Consider this pump:

JABASCO BILGE PUMP Model 31705-0092 bilge-shower-drain-pumps/31705-series-31705-bilge-and-shower-drain-pump. htm

This pump can be mounted in a dry place, above the sump. It will lift water to the pump up to 7-feet vertical lift. It will pump about 4-GPM or 240-GPH. That is a real output figure. Put a strainer ahead of the pump, near the pump so you can clear it out if needed. You have to control the pump manually. If you want a float switch or some water-sensing switch you will have to rig that up yourself.

I am thinking of using one of these to evacuate water from the live well in my boat. I have a Rule centrifugal "bilge" pump in there now and it is terrible. Worst pump I have ever seen. I don't know why people keep using them.

DVollrath posted 11-13-2012 09:47 PM ET (US)     Profile for DVollrath  Send Email to DVollrath     
I use one of the Rule automatic pumps in my Montauk. It has done what it is advertised to do. The auto-sense feature works well, and does not put undue load on the battery. I have had it on auto for 3 weeks at a time, after which my (rather small) Yamaha F70 started right up. The alternator charge voltage was 14.5V+, so apparently it didn't use too much of the battery's capacity.

I have the output hose routed over the low portion of the transom, which is perhaps a 24" rise. I have not measured pumping capacity with that lift load, but from the rule spec:

500 GPH @ Open Flow
360 GPH @ 3.35' lift
280 GPH @ 6.7' lift

480 GPH @ Open Flow
310 GPH @ 3.35' lift
180 GPH @ 6.7' lift

If the motor was not running, I'd guess mine would be pumping 350-380 GPH. Clearly diminished, but still pretty good.

As JimH mentions, they are relatively cheap. I hope it lasts...


Chuck Tribolet posted 11-14-2012 11:45 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
What LHG and Dvollrath said, except that there's no way I'd
use wire nuts anywhere on a small boat. Solder the conection
and use Ancor hot-melt-glue-lined heat shrink.

What counts is the pump intake to hose output distance, not
pump intake to top of transom.

I've run a Rule 500 GPH chip sensing pump for years in my
Montauk and it's just fine.

Do use the more expensive hose that's smooth on the inside.
There was a noticeable improvement in flow when I changed out
the corrugated on the inside hose.


6992WHALER posted 11-14-2012 12:09 PM ET (US)     Profile for 6992WHALER  Send Email to 6992WHALER     
I have the Rule 500 in my fish boxes. It works just fine but I am very paranoid it will kill my battery. The noise from the constant cycling on and off is very annoying. Especially at night when you are trying to sleep. I wired a power switch to it so I could turn it off.

I would much rather have an automatic pump with a built in float switch.

I did have one of these pumps fail in 2010. It would cycle on but it did not sense the water so it just turned off. I replaced it with the same pump for ease of installation. Still kicking myself for not changing to a float switch.

jimh posted 11-14-2012 01:29 PM ET (US)     Profile for jimh  Send Email to jimh     
Another way to look at the automatic sensing pumps: they continually discharge the battery to see if they are needed. Once they figure they're needed, the battery is dead.

A float switch consumes no power nor does it run the pump. It just comes on when its needed and shuts off when done.

L H G posted 11-14-2012 03:01 PM ET (US)     Profile for L H G    
Much to the shock of all of you, and to Anchor who sells all that high priced connector stuff, Life Seal filled plastic wire nuts work better than ANYTHING I have tried for UNDERWATER or continuously wet connections, and when concealed from view, of course.

Properly twisted and sealed in Life Seal caulking, my own experience is they are totally salt waterproof, even when continuously under water. I have one such connection for a bilge pump in my Outrage 18, done 10 years ago and it still works perfectly with no corrossion. When the boat is in the water, this connection is always under water.

Other then wet bilge pump connections, the only other place I use them is on trailer wiring. Even since I started doing this, on the advice of Clark Roberts, I have ZERO trailer wiring connection failures.

If you don't believe how well these work, try it, you'll like it!

On this particular pump shown in my Montauk, the wiring is designed so if the pump needs replacement, it is simple. No tunnel wire pulling, no contortions. The leads from the pump are cut very short, so that the connections (wire nuts) are right there. Because this forces the wiring connection to this wet area, the wire nut detail made sense to me, since I know they are fail proof.

breakaway posted 11-14-2012 05:41 PM ET (US)     Profile for breakaway  Send Email to breakaway     
Thank you all for your advice. The constant noise from the auto sensor cycling on and off does sound annoying. I will see if I can fit a Rule 500 pump with a built-in float switch into the bilge. If not, I will probably set up a Rule pump with a separate float switch.
L H G posted 11-14-2012 05:59 PM ET (US)     Profile for L H G    
First of all, there is no noise from the pump. You can't hear the sensing. Secondly, because an on-off pull switch is used, the pump only works when it is "on", which is pratically never. In my situation, the pump is on about 1/1000th of the time I am in the boat. I mostly use it for boat cleaning, or when it is raining heavily or taking large amounts of spray over the side, which rarely happens. Otherwise, it's turned off. If I leave the boat at a dock for a night or two, and rain is in the forecast, I turn it on. Battery run down does not occur.

Now, if the boat is moored/docked without a cover, and unattended for weeks, then the separate float switch is a better choice. But otherwise, it's not.

DVollrath posted 11-14-2012 09:17 PM ET (US)     Profile for DVollrath  Send Email to DVollrath     
I can only offer my experience to date, which is admittedly rather short at 6 months, and the specs of the device itself.


Another way to look at the automatic sensing pumps: they continually discharge the battery to see if they are needed. Once they figure they're needed, the battery is dead.

I'm hopeful this is a bit tongue in cheek, as the case mentioned, while possible, is the pathologically pessimistic scenario for this pump. All systems have them, but their likelihood is rather remote. The one for the mechanical float switch might be that corrosive failure renders it unable to close contacts just before the monsoons hit.

The spec for the device states that the sensing cycles consume .2Ah/day (on the package mine came with) or .5Ah/day from the website. I'll give my reasoning on a more likely conservative personal scenario. Assumptions are:

A single group 24 battery, 54aH new, derated to 27aH due to age and maintaining reserve for starting the motor.

.5Ah per 24 hours for sense operation
1.9A draw during pumping @ 12V

2" of rain in a 15 min duration on a classic Montauk with no cover (it all gets in the boat).

Total gallons to pump are:
16'7" * 6'2" ~= 102 sqft * 2/12 = 17 cuft of rain water, which is about 17*7.5 = 127.5 gallons of water.

Using the 350GPH estimate, this will take around 22min to pump out. Round it up to 30min, and the pump will use .95Ah. Round this up to 2Ah for Peukert's law effects, system aging, temperature etc still means you have 27Ah-2Ah = 25Ah of capacity left for auto-sensing during the time leading up to the deluge.

At .5Ah/day, this means you have 50 days of capacity. You guys who take better care of your batteries, have a dedicated starting battery, and/or buy the group-Mongo capacity variety will have even more duration (or peace of mind).

I don't plan on leaving my boat unmonitored in its slip for 7 weeks, but I'm gaining more confidence I could if I needed to.

The autosense logic is a solid-state device, which can have some reliability advantages over mechanical devices, but it's all in the implementation details. For me, I'm comfortable with the theory enough that I installed one. Time will tell if they did a good job on the design.

Other comments & observations:
I am pretty sure that the head the pump need to work against is a major factor in reducing its capacity. Tubing length, diameter, and interior smoothness factor in as well.

I absolutely can hear the pump cycle on my little Montauk. However, I never have the pump on auto when I am in the boat, so it is not a source of annoyance, to me at least.

I know the group will point out flaws in my reasoning and/or math in its usual kind and gentle manner :)


6992WHALER posted 11-14-2012 11:24 PM ET (US)     Profile for 6992WHALER  Send Email to 6992WHALER     
Larry the pump turns on every 2.5 minutes to see if there is water to pump. I don't know how you can say it does not make any noise.

In my situation the pump is the third pump on board. I have two bilge pumps in the bilge so I would like it better if it turned on every 15 or 20 minutes. It would be nice to be able to set the time between cycles.

As I said before I am paranoid that it will run down my battery. It just bothers me that this this pump turns on and off every 2.5 minutes.

jimh posted 11-15-2012 08:08 AM ET (US)     Profile for jimh  Send Email to jimh     
Dennis--Great job on analyzing the power consumption.

The electrical switch in the float switch at one time was probably a mercury switch. Since mercury is conductive and a liquid at most temperatures that you'd like to go boating, it was used in float switches as a very reliable contact closure for controlling electrical current. I suspect--but I am not certain--the modern float switches have gone to something less expensive (and perhaps less environmentally hazardous) than mercury for the switch. The reliability of the float switch is perhaps not a good as it used to be. A float switch could also be jammed into the ON position if something floated over and became lodged under the switch.

There are other methods of sensing water that can be used besides a float switch, but they're probably all more expensive.

The auto-sensing of the centrifugal pump is a good adaptation of one of the pumps biggest weaknesses: it cannot lift water to itself and it cannot prime itself. If there isn't water flowing downhill into the pump's inlet and into its centrifugal impeller the pump will just spin and do nothing. That is how the auto-sensing works: if the pump motor spins without drawing much current (because the impeller is free-wheeling) it decides there is no water. If the pump spins and the motor draws more current, the pump decides there must be a load (water) and it continues to run.

ericflys posted 11-15-2012 12:22 PM ET (US)     Profile for ericflys  Send Email to ericflys     
Jimh, your making stuff up again. The Rule-mate pumps up through the 1100GPH size do not run the pump to sense if water is present. It uses two sensors and uses a "dielectric constant" which only allows it to sense the dielectric constant of water and will not turn on automatically if your bilge is filled with gas. There is some power consumed by the sensor (one is used to turn the pump on, and the other to turn it off) but it is quite low.

I use the 2000GPH model that uses a float switch contained within the housing. I like having a pump of at least 2000GPH because operating in some rough conditions, I need to get water out fast on occasion. When going with the Rule-Mate pumps bigger than 1100, having a two battery system with an isolated engine start battery becomes more important as the pump I have uses over 8A when turned on. It does not have any draw when in standby.

jimh posted 11-15-2012 12:29 PM ET (US)     Profile for jimh  Send Email to jimh     
I am not making up stuff. Why does John's pump run periodically if it is not sensing the load on the pump? Perhaps there is now a newer method in use in some pumps.

Measurement of the medium surrounding the pump for its dielectric constant sounds very interesting. Can you give us a pointer to where this process is mentioned in conjunction with a particular brand and model of bilge pump. Otherwise, I would begin to think you were making stuff up.

jimh posted 11-15-2012 12:35 PM ET (US)     Profile for jimh  Send Email to jimh     
Dozens of vendor websites reprint this information on how Rule automatic bilge pumps operate. Here is an excerpt:

Automatic Bilge Pumps
These feature computerized operation on the principle of impeller resistance. Float switches are not required. The pump will turn on every 2-1/2 minutes for about one second to sense for water. If water is present, the pump will sense resistance and continue to run until all water is removed. When the water's gone, it will resume checking for water every 2-1/2 minutes. Power use in the checking mode is minimal.

Eric--I think you must agree that your accusation that I was making this up is completely false. This above quoted passage is precisely what I described in my earlier article discussing how the automatic pumps operate.

russellbailey posted 11-15-2012 01:29 PM ET (US)     Profile for russellbailey  Send Email to russellbailey     
There are two types of automatic operating Rule pumps.

Rule-Mate senses water without turning off and on.
For example, Model RM750A

Rule Automatic pumps cycle on and off every 2.5 minutes and use impeller resistance to decide if to stay on.
For example, Model 25S

6992WHALER posted 11-15-2012 02:14 PM ET (US)     Profile for 6992WHALER  Send Email to 6992WHALER     
Well that is an interesting piece of information.

But I still think LHG is showing a 25S rule pump in the picture above.

ericflys posted 11-15-2012 02:22 PM ET (US)     Profile for ericflys  Send Email to ericflys     
Jimh, you are incorrect and perhaps too proud to admit it. Everyone in this dicussion from the second post on, except you and 6992whaler have been referring to the Rule-Mate series of pumps. The pumps that are being referred to as "chip sensing" are Rule-Mate 500, 750, or 1100 pumps, which you state and quoted a bunch of incorrect information about. The information you state may be from a previous generation of pump from long ago.
ericflys posted 11-15-2012 02:26 PM ET (US)     Profile for ericflys  Send Email to ericflys     
I stand corrected. I was not aware they still manufactured the "automatic series", I thought they had been completely replaced by the Rule-Mate series. My apologies Jim. It appears we we're posting revelant info, just about two different pumps.
ericflys posted 11-15-2012 02:32 PM ET (US)     Profile for ericflys  Send Email to ericflys     
The Rule-Mate series has some advantages over the automatic series of Rule pumps. For instance, they come on as soon as water is present, run for a set period of time after water is gone, which will evacuate water to slightly lower than the pickup (don't ask me how this works) and consume less energy in standby with less chance of malfunctions.
L H G posted 11-15-2012 04:30 PM ET (US)     Profile for L H G    
Most of the time the pump is turned off, since most of the time there is no water in the sump. The thing works for me, makes a super clean installation in the Montauk, and I never hear it run or sense for water over the sound of the engine. The teak sump cover conceals a lot of the minimal sound.

I don't sit in the Montauk at a dock when it's full of water, or pouring rain, and listen to it run. 99.9% of the time when the pump is pumping out small amounts of water, the boat is underway with the engine running. I turn it on with the switch, let it pump out the rain or spray, and turn it off again.

If the boat is docked overnight in a Tropical Storm, then the I don't hear the pump turning off and on because I'm home in bed.

That contraption Jim is talking about would be ridiculous in a Montauk.

6992WHALER posted 11-15-2012 04:58 PM ET (US)     Profile for 6992WHALER  Send Email to 6992WHALER     
The Rule-Mate 500 Automatic Bilge Pump is a blue and white rectangle/box shaped unit, that senses water electronically. $66.99 West Marine Rule model #RM500A

The Rule 500 Automatic Bilge Pump is a red white and blue cylinder shaped unit. It turns the pump on every 2.5 minutes to test for water. $66.99 West Marine Rule model #25S

It is obvious that there is confusion as to which pump we are talking about.

I have a Rule 500 Automatic Bilge pump Model 25S. This is the pump that is pictured in LHG's link, if he had linked to a picture of the Rule-Mate 500 model RM500A I would not have joined the conversation.

I have no experience with the Rule-Mate 500 Automatic Bilge Pump model RM500A.

jimh posted 11-15-2012 05:08 PM ET (US)     Profile for jimh  Send Email to jimh     
Eric--I have only spoken in generic terms of centrifugal pumps. My comment about the automatic sensing was made after John spoke of his pump which runs all the time in order to sense the impeller resistance. I described the method accurately, as far as I can tell.

As for the Jabasco "contraption" (as Larry disparagingly calls it) I mentioned, it will probably outlast ten centrifugal pumps. By the way Jabasco and Rule are just brands of the same company. They make all sorts of pumps, at many different prices, for many different applications, of varying durability and quality. If you want to buy the least expensive, plastic, non-repairable, throwaway pump, follow Larry's advice and then install it so its electrical motor will be submerged in water.

The requirement that a pump must fit into the sump from which is will evacuate water is not a binding criterion. It is only a requirement if you use a pump that cannot lift water to its intake and cannot self prime, like a centrifugal pump.

I did read that some of these modern water sensing controllers can also tell if the pump is submerged in oily water. If the pump senses oily water it does not run. I think this this is a strange control method. Let me analyze it:

--pump senses oil in water; does not run, preventing oil from being discharged to the sea

--water continues to rise in boat; pump continues to not run;

--boat sinks, discharging oily water to the sea

Exactly how did the pump save the environment in that scenario?

jimh posted 11-15-2012 05:11 PM ET (US)     Profile for jimh  Send Email to jimh     
ASIDE to Eric--You were very gracious to offer an apolgy, and I appreciate that. I also appreciate your information about the new sensing method. But I would like to know more about the method. If you see some reference material that explains the technique in more detail, please let us know.
6992WHALER posted 11-15-2012 06:55 PM ET (US)     Profile for 6992WHALER  Send Email to 6992WHALER     
Jim, I had the exact same reaction to the non oil pumping pump, when I was reading up on these pumps.
DVollrath posted 11-15-2012 07:14 PM ET (US)     Profile for DVollrath  Send Email to DVollrath     
Perhaps the Rule-mate operation might work out as follows:

Oil is lighter than water, and hence floats on top of it.

If sufficient water is present, the oil will be pushed above the sensor, and the pump will turn on until the fluid level is reduced, the oil is sensed by the pump, and the pump shuts off.

Seems like some oil would be ejected at any rate due to hysteresis of the sense/pump/sense cycle, but perhaps it would minimized.

No boats were sunk during the construction of this hypothesis...


tmann45 posted 11-15-2012 10:04 PM ET (US)     Profile for tmann45  Send Email to tmann45     
Rule makes three types of bilge pumps: Non-Automatic (manual or you add float switch), Rule-Mate Automated (has built in magnetic float switch) and Automatic (the computerized turn on every 2.5 minutes to sense water).
jharrell posted 11-15-2012 10:33 PM ET (US)     Profile for jharrell    
Rule-mates use a field effect sensor, the technology is explained here: UKWtn4e9KK0

There are conflicting reports on how well the work compared to the load sensing automatics. They are also larger, so they may not fit in the Montauks bilge, I mean to measure one and find out. They should not make noise and use very little power for sensing, they also have a threaded output and come with straight and elbow fitting for discharge.

While I agree with jimh the Jabasco is a superior pump I also agree with LHG it is very large for a Montauk, and if mounted outside the bilge would be a shin hazard. These would be preferred however on a larger Whaler with more bilge or other enclosed space for mounting..

The Rule automatics seem to be tried and true in Montauks, most likely because of thier size and the sensing technique adds almost no complexity to thier design, however the cycle noise seems to be an annoyance to some.

jharrell posted 11-15-2012 11:17 PM ET (US)     Profile for jharrell    
Looking around some more I stumbled upon another pump using a field effect sensor that may be a better design for the tight space in the Montauk bilge: Product_ID=10002&FriendlyID=Supersub-Smart-Family

jimh posted 11-16-2012 07:41 AM ET (US)     Profile for jimh  Send Email to jimh     
Thanks for the very interesting information on WHALE pumps. What could be more appropriate for a Whaler than a WHALE pump? This reciprocating diaphragm pump looks very interesting: Product_ID=10003&FriendlyID=Bilge-IC

I like using a diaphragm pump for a bilge pump application because a diaphragm pump can tolerate debris flowing through the pump. A teeny little centrifugal pump will not be able to pump out any debris other than very small stuff. A diaphragm pump can handle more stuff. I like everything about this pump, but the price (from West Marine) is over $300 for the whole system, rather expensive kit.

jharrell posted 11-16-2012 09:04 AM ET (US)     Profile for jharrell    
Yes the larger Whale IC pump looks like a very nice design. Again however it is very large for a Montauk and as you mentioned rather pricey compared to the $59 Smart Supersub 650GPH.

Overall Whale pumps provide much more information about their products and seemed much more focused in their presentation compared to the Xylem/Rule/Jabasco conglomerate, giving me more confidence in their designs.

I may order one of these for my Monatuk: jsp?path=-1%7C51%7C299222%7C84462%7C316440&id=1207040

tmann45 posted 11-16-2012 09:05 AM ET (US)     Profile for tmann45  Send Email to tmann45     
Rule does not make a bilge pump that uses "dielectric constant of the material in which the pump is submerged" to turn the pump on or off. They might make a "float switch" that uses that technology.
jimh posted 11-16-2012 09:20 AM ET (US)     Profile for jimh  Send Email to jimh     
In the course of the discussion someone--not me--introduced the notion that there was a control system used in pumps in which the dielectric constant of the medium near the sensor was measured, and by such a measurement the pump control system was run. I would like to read an explanation of the technical basis by which a control system is implemented for a pump by measurement of the dielectric constant of the medium near the pump. If anyone wants to assist me by pointing to a resource that explains that, I would appreciate it. Thank you.
jimh posted 11-16-2012 09:21 AM ET (US)     Profile for jimh  Send Email to jimh     
jharrell--Yes, thanks again for pointing to WHALE pumps. Here is a good listing of them from DEFENDER, which seems to carry their full line and at decent prices:

jimh posted 11-16-2012 10:03 AM ET (US)     Profile for jimh  Send Email to jimh     
It may be interesting to note that Brunswick also makes pumps under their brand name of Attwood, just as Brunswick makes boats under their brand name of Boston Whaler. I suspect that you might find an Attwood pump on a Boston Whaler. For readers who think that Brunswick makes the best of everything, you will want an Attwood pump.
jharrell posted 11-16-2012 05:34 PM ET (US)     Profile for jharrell    
The original Rule-Mate design used a standard float-switch introduced in 1999. Rule now produces the Rule-Mate "A" models that use a field-effect sensor: Rule-Mate-Bilge-Pumps-Product-Announcement.htm

This sensor technology perhaps could be described as using the dielectric constant of water but is generally referred to as "field effect".

It is unclear whether they still manufacture the original Rule-mate with a standard internal float-switch in the 500,750, and 1100 GPH models.

jharrell posted 11-16-2012 05:39 PM ET (US)     Profile for jharrell    
Here is a more detailed explanation of field effect water sensors: http:/ / ezinearticles. com/ ?Field-Effect-Sensors-Eliminate-Pump-Switch -Failure:-Residential-Applications& id=5904441
tmann45 posted 11-16-2012 10:27 PM ET (US)     Profile for tmann45  Send Email to tmann45     
jharrell, thanks for the update.
jimh posted 11-17-2012 07:51 AM ET (US)     Profile for jimh  Send Email to jimh     
I searched on the terms "dielectric constant pump control". In the first search using Google I found this reference as the first suggestion to my search:

The patent explains the method.

swist posted 11-17-2012 08:41 AM ET (US)     Profile for swist  Send Email to swist     
I have had 4 different Rule pumps, both sensing and float-actuated, in various boats over many years. It is true that they don't appear to be very substantial, and surely they are cheaply made because they wouldn't sell at those low prices otherwise. Note "low" in a marine product context :-)

Except that they don't seem to fail (at least not mine), and I keep my boat on a mooring, uncovered, so I get maximum use out of the pump. They have all been located in cruddy saltwater bilges or equivalent. After a while, they even look like crap. I don;t care if they leave a little water in the sump, or don't produce much head - they lift the water as far as they need to, which isn't far in a small boat.

They are simple, with as few moving parts or other complex components as possible, which probably explains their longevity. When I find a marine product that delivers value for reasonable money, I stick with it.

jimh posted 11-18-2012 07:02 AM ET (US)     Profile for jimh  Send Email to jimh     
On my 1990 Boston Whaler boat there probably is a RULE-branded centrifugal pump in the cockpit sump. It only has to lift water about 8-inches from the bottom of the sump to the outlet fitting on the hull sides. If you put that same pump in the bottom of a deep live well and routed the output up and over the transom, the height that water must be lifted will be much greater, perhaps three feet, and the pump output would fall off noticeably.

That RULE pump on my boat is probably the original pump from 1990. The motor in the pump only runs about a total of three minutes per year. That is a duty cycle of 0.000005, so you might expect with such light duty the durability would be good.

RickS posted 11-18-2012 01:11 PM ET (US)     Profile for RickS  Send Email to RickS     
My 1996 Ski Nautique has a water sensing bilge switch called a Water Witch. It is the original factory installed switch and still works well.
jimh posted 11-19-2012 07:29 AM ET (US)     Profile for jimh  Send Email to jimh     
The Water Witch looks interesting but is seems to have a fatal flaw: it does not detect rain water! From their literature:

In some cases where there is alot [sic] of rain water entering the bilge, the water may be too clean for our sensor to see. In these rare situations the best course of action is to manually activate the bilge pump to remove the rain water....
swist posted 11-21-2012 09:11 AM ET (US)     Profile for swist  Send Email to swist     
I don't follow water-sensing technology, but I too never liked the way the pumps I owned of that kind kept turning on to "look for water" and then turn off at regular intervals.

Is there no way of sensing water, including rainwater, including saltwater, including dirty or clean water, that can't be done with some widget with no moving parts?

jharrell posted 11-21-2012 10:42 AM ET (US)     Profile for jharrell    
The field effect sensor technology discussed earlier in this thread, used in the Rule-Mate A series and Whale SuperSub models seems to fit your criteria. Unless by dirty water you mean oil.

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