I'm a yachtie, I live on my boat and sail. In heavy seas the bilge has water in it (always) and the water running back and fourth sets up a wave that runs from front to back, everytime it passes the "bilge pump switch" the pump starts, all boats have this problem. It's only momentary, and the pump stops again, this happens twice with each wave, once when the bow comes up and the water in the bilge runs back, and again when the bow goes down. What I need is a timer that will delay the start, until the pump has had a contact from the switch for 4 or 5 seconds, that would eliminate the momentary spikes from the switch in heavy seas. the second half of the problem is, the pump should run a little longer than the stop point of the switch, the bilge never really gets pumped out because the switch goes open when there's still about an inch of water in the bilge. So, what I'm looking for is a timer that delays the start to get rid of the momentary hits and then runs for an adjustable amount of time after the switch says stop. I really think a guy could get rich with a "smart bilge switch", why don't you develop it and I'll split the millions with you... All boats need them, I've known it for a long time and think I know how to fix it, just haven't taken the time. I've worked on heavy equipment with start stop timers, but they were pretty complicated, and I think it can be done pretty easily. Needs to be 12v, I'm going to pull up a relay to feed the 8 amps the pump needs. If one is sailing in even choppy seas and you have some way of monitoring your pump, you'll find out how often it runs for just a second and then goes off. Years ago I wired a led in tandem with the pump so I'd know when the pump was running and sometimes in heavy seas, I just go down and shut it off which really isn’t a very good solution. It’s hard on the switch and the pump to cycle on and off constantly like that. hope you can help.

 

If you are capable of putting together an electronic circuit, it's a fairly simple time-on/ time-off circuit.

Two timers are required.

Off the shelf, use a 12vdc delay-on timer relay into a 10A, 12vdc, delay on break timer.

An HVAC fan timer would be great, but work on 24vac.

edit:

Here's one.
12vdc
15amp
on and off delay

http://www.airotronics.com/pdfs/Airotronics-026_TGCM~TGCML.pdf

 

Here is another delay-on-make/delay-on-break relay. There are likely other similar devices available.

 

Personally I'd try to solve this problem mechanically. I'd either put baffles across the bilge or locate the pump switch at the base of a chamber with restricted water in-flow from the bilge. That would 'smoothe out' the sloshing; rather like using a smoothing/reservoir capacitor in electrical circuits.

 

alec t, thats the way to do it. like the gas tank in a race car, or the fuel tank in a plane, baffles to stop the sloshing and a "sump" to even the supply to the pump.

 

In practice it may not be so easy to implement a mechanical solution.

Here is a minimum component idea.
Not a real timer, just an integration capacitor for a small delay.

 

In practice it may not be so easy to implement a mechanical solution.

True; but we do tricky here at AAC, as well as easy

 

For anyone who works with microcontrollers this is a trivial problem. One chip could read the switch, provide delays, and drive the relay (thru a driver transistor). I've probably got some relay timer boards around that could do this handily as they are made to drive a relay.

I am curious what the "bilge pump switch" consists of.

 

What I need is a timer that will delay the start, until the pump has had a contact from the switch for 4 or 5 seconds, that would eliminate the momentary spikes from the switch in heavy seas

The downside of any delay arrangement is that you lose valuable pump run-time precisely when it's most needed, in heavy seas (assuming it's water breaking over the boat which is filling the bilge). Better, I think, to have a timer which when triggered by the switch will keep the pump running for some minimum time, e.g. 30 secs.

 

The downside of any delay arrangement is that you lose valuable pump run-time precisely when it's most needed, in heavy seas (assuming it's water breaking over the boat which is filling the bilge). Better, I think, to have a timer which when triggered by the switch will keep the pump running for some minimum time, e.g. 30 secs.

The OP wants a adjustable delay for both ON and OFF which should satisfy your concerns.

 

Hello there. I would solve to problem in another way. You must have water tight baffles every few feet or yards, depending on size of boat. If you don't do this.....you can put a quantum computer on that pump to no avail. You must put one way flapper valves at the bottom of the baffles. You can orientate the valves to direct water to bilge section where pump is located. We want to gather the bilge water in one place and keep it there under sailing conditions. Now you can play with the pump. I'll bet it takes a lot of money to do that. That's what keep the bilge pump business in business. Bilge pumps are cheap.

 

It's a switch that is screwed to the bottom of the bilge and has an articulated arm that floats on the top of the water, usually a mercury switch inside. Contact is made by the water level rising, and when enough water has pumped out, it goes open.

 

Hello there. I would solve to problem in another way. You must have water tight baffles every few feet or yards, depending on size of boat. If you don't do this.....you can put a quantum computer on that pump to no avail. You must put one way flapper valves at the bottom of the baffles. You can orientate the valves to direct water to bilge section where pump is located. We want to gather the bilge water in one place and keep it there under sailing conditions. Now you can play with the pump. I'll bet it takes a lot of money to do that. That's what keep the bilge pump business in business. Bilge pumps are cheap.

Can we get Maxwell's demon to run the flappers?

Then we can toss the pump entirely.

 

One-way valves are common on boats, no demon required.

 

We need nothing from Maxwell to solve this problem. Ampere experimented with STATIC charges and currents. Maxwell knew this and stated so with his equations. No one remembers that. Thus the first step in a long fairy tale called QM. Weber. Weber, the greatest experimenter of all time. If Maxwell had used Weber.....we might have derived the universal force law 80 years ago. So after going back and repeating experiments...the true structure of matter was found in the 90's. From this structure, all properties of particles was explained and the cause or force for such properties explained. After putting all this together.....they found another very weak term..... Gravity. The universal force law or unified field theory was derived in the 1990's. The greatest discovery in science and nobody's heard of it. There are thousands of people, schools, governments who are invested with QM and GRT. They have reputations and careers. They will not give that up for a simple and elegant way the universe works. So....we still need the flappers and the pump.

 

Huh? What possible relevance does quantum theory have to a bilge pump?

(Despite the obvious comparison of a theory you don't like to bilge water.)

 

Just use a delay make/break relay and forget all the pseudo-scientific garbage. This site gets more ridiculous by the day.

 

The useful point from #4 is that a mechanical solution can be a significant part of the solution, and might even eliminate the need for an electronic solution. There are other reasons you don't want that bilge water rushing back and forth.

But installing baffles is likely impractical for the OP unless he has good access to his bilge. Easy for the boat builder, not the owner.

 

I doubt that the bildge water affects much of anything aside from intermittently activating the pump. I only bother to pump mine out occasionally. Remember we're only talking about a small amount of residual water the pump leaves behind.