home built electronic bilge switch

[cooper]

Hi all ..l am looking into the possibility of making a pair of electronic bilge pump switches. The idea is to have a switch on point , a oh my gawd the pump is not keeping up point , and a timer to turn it off after the water goes below the lower point. Sensing water conductivity seems to be the simplest way at the moment, but if anybody out there has done the exersise or mucked about with it ............

[GordMay]

Not exactly what you describe, but you might find this Bilge Pump circuit interesting:
http://www.cruisersforum.com/gallery...=500&userid=79

The circuit uses an “Ultra Pumpswitch #WPS-01-12V” two-level float switch.
[size=1} Ignore the scribbling at the margins - this was provided to someone looking for a DT light control circuit)[/size]

I could FAX, or MAIL clearer copies, of this & other, diagrams that would serve your purpose.

HTH, Gord

[LtBrett]

Check out a water witch. Very reliable, not very expensive, uses the technology you describe.

Brett

Anything bilge - bilge switch, high water, bilge counter

[Alan Wheeler]

While on this subject, has anyone got a circuit for making an electronic level detection (float) switch??

[coot]

Originally Posted by cooper

Sensing water conductivity seems to be the simplest way at the moment, but if anybody out there has done the exersise or mucked about with it ............

I used two commercial bilge float switches. They are just mercury switches inside a plastic housing. The lower one is mounted on a shim, and the upper one is mounted on a thicker shim. I have two bilge pumps, but normally only one runs because the water never gets high enough to turn on the upper switch. I don't need the timer that you hypothesize because the switch has enough hysteresis.

There is no reason these switches have to switch the pump directly. You could easily use them for input to a microcontroller that implements your switching/alarming algorithm. I've thought of wiring the upper switch to a buzzer in parallel with the pump, but I've noticed that just the sound of the pump running usually gets my attention.

I've seen level sensors that use changing capacitance to measure liquid level. The circuit is like a theremin. A stud sensor uses the change in capacitance cause by the dielectric constant of the wall.

Non-contact sensors are big in some industrial applications. The big things there seem to be ultrasonic and optical, but the parts are expensive.

What advantage are you trying to achieve over a mechanical switch?

[NoTies]

When I was working on large ships we had a saying:- "do you want reliability or electronics?" In fairness it's usually the engineering protecting the electronics that lets the system down. I like clunky , simple & reliable for safety equipment.
AFAIK a capacitance probe will only detect salt water and will be useless in fresh. No good if on a lake or river or if your freshwater tank decides to give up. Also no good for rain ingress.

[cooper]

Interesting comments. The reason for electronic is that it cant be jamed either on or off by any floaties in the bilge. My boat sits on a mooring looking after its self for up to a couple of months at a time. Some rain water got in and turned on the bilge pump and it stayed on........Although in some circumstances electronics can be suss, l have found that simple circuits in permenant water tight enclosures to be very reliable. l made LED nav lights years ago....and have not touched them since. The conductivity of fresh water is still quite enough for the system to work (l did some tests with a multy meter) including testing salt residue, that l slowly dampened. The ultrasonic and capacitance type systems seem to tricky and expensive for me. The guys at work here make all sorts of these types of systems including proximety switches for nursing home patients.....thanks gord l will be in touch.....and thankyou everyone else, this is what makes this forum..cheersMartin

ps l am hoping that the only time my bilge pump turns on ,on my new boat is when l have a shower or do the dishhes....M. PPS ! wheels if l get the system working it will do what you want with only some small modifications.

[Alan Wheeler]

The biggest headache I have is replacing the damn float switches. And it doesn't seem to matter what I have used so far. All of them fail. I have used Rule, which I found to be the worst so far. Surebail seem to stick easily, but at least so far, they have always been in the on position. I have just started trying Attwood. That seems OK so far, but I had one stick in the on position the other day after my hell trip. Haven't looked at what the problem is so far. So I figured if the float switches are such a hassle, the electronic maybe the better idea. Johnston have just released here, a fully solidstate unit for $89.00. About the same price as a float switch. That maybe my next try.

[cooper]

wheels are you after a bilge type switch ie on /off, or do you want a level reading type ie fuel tank ?

[hellosailor]

Wheels, I don't think any of the laws of phsyics (or Mr. Murphy) have changed since PS did a review on "new" switches maybe 20 years ago. The problem is, they all have to work in a lousy environment and people need them to be cheap and robust--two contradictory things.

The ones using mercury switches are simple, but the the "float" itself is always problematic because it can and will be jammed, or bilge oil will gunk up the pivot, or some idiot supplies 6" long wires so those are now spliced below the water level, and making a good water-and-oil-proof splice is a black art only known to telephone company linemen.

The electronic solid state ones all seem to have problems because they sense conductivity--and the mix of salt water, fresh water, corrosion, and oil products always manages to screw that up. Of course, a smarter solid state one could figure that out--but that would mean a computer chip, more money and less reliability.<G>

Bottom line seems to be, install two pumps, each capable of doing the job solo, each with a separate switch, and expect that every year or two, something will fail and need to be replaced. The alternative would probably make the famous ten-thousand-dollar-coffepot on the B1 look like a model of underengineering.<G>

(And that coffeepot wasn't really overpriced, it was just that apparently someone wrote a spec saying it needed to "retain" all the beverage even during a crash.<G>)

[Alan Wheeler]

(And that coffeepot wasn't really overpriced, it was just that apparently someone wrote a spec saying it needed to "retain" all the beverage even during a crash.<G>)

Now that's funny. Crew and Blackbox didn't survive, but the coffee did.
Yeah coops, it's bilge water. Even though I am maticulouse at keeping the bilge clean, I have a Perkins, so oil in the bilge is always an issue and that seems to be hard on float swithces. I also find the murcury switch is not good at high current operations. The big pumps cause them to fail faster than the smaller pumps. I thought of switching a relay, but figured on more complexity is not a good idea either.

[cooper]

Hi wheels
on my "boat on the water" at present l have a large float, with a large weight inside a piece of 100 mm pvc drain pipe with small holes drilled in it.. this is attached to a piece of plastic coated stainless wire, that runs up inside a stainless tube. At the other end of the stainless tube is a weighted rocker. with a
magnet and a fixed sealed reed switch (of the door alarm type) connected to a relay. The electronics are a metre above the bilge in a lunch box !!. The whole thing works briliantly.........except ...it seems that the bilge goop with a capital "G" (40 year old single cylinder) has some how made the closed cell foam block sticky which has caused the switch to stay on. l could coat a new block with somthing to protect it and put the whole lot back together and get another 6 years, but seeing as l need three switches for "boat not yet on water" l thought l would sort out a simple solid state one. They are available for as little as $29 US plus postage. Even so l thought l would see what l could come up with. If l get success l will post it here.

[Strygaldwir]

When I bought my boat, I replaced all the switches and pumps (6 of them) With rule pumps (Rule 2000s and the high capacity switches) and switches. Over the next 6 months, I tested them regularly. I found during that time that I had 3 failures in the switches!!! VERY UPSETTING!! I have since replaced the 4 critical pump switches with the electronic types. I have had one "failure" in the electronic switches in the subsequent 2 years. That "failure" was when a fitting on my fresh water system broke and i proceeded to pump 100 gallons of RO water into my engine room. The water was amazingly pure, and apparently the switch didn't detect it. As I was underway at the time, I didn't notice it until I stopped and noticed my amp usage was abnormally high. I found the water pump had drained my tank into the engine room. After flipping the manual switch, no problems. Run the water maker for another 6 hours and remember to shut down the water pressure pump when underway.

In anycase, I still check the bilge system once a month or so, no further issues with the pumping system. I got the electronic switches from West Marine for about $30 each. Well worth it so far! Heck of a lot easier than engineering and constructing my own solution.

Cheer

[Alan Wheeler]

I have had great results from Rule Pumps, Simply terrible results from their float switchs. The seriuosly need to sort their switches