We recently installed a "automatic" pump in the forward bilge on one of
the charter boats. The way I understand it, the pump spins its impeller
and if it detects water, it keeps pumping. No external switch needed.

Have a look at the link below.

http://www.westmarine.com/webapp/wcs...productId=2576

Capt. Frank

Keith wrote:

Groco makes an air activated switch like this for boats. I have one in mine
and love it. The only thing sticking down into the bilge is a little bell
shaped upside down "cup" with the hose leading up to the switch, a couple of
feet above. When the water rises, the pressure inside the switch triggers
the bilge pump.

"MIDEMETZ" wrote in message
...

I used a water switch from a washing machine. I don't remember the size

of the

PVC cap but it was used by a lot of the local shrimpers in their old

wooden

boats ( read leak a lot ).

The switch is usually in the control top part. They recommended using a
smaller longer hose and mounted the switch high on the bulkhead.

Mine worked for a little over 5 years with out problems. ( Sold the

boat ).

It would take a little experimenting but easy engulf to find the cap size.
They heater a brass hose barb and just screwed it in to the hole, I

drilled &

taped it. It isn't boat pretty but very useful.

For the delay the Radio Shack idea seems the best.

Mike.
*****************

However I am sick of replacing bilge pump switches. ( I have a
shed full of floats!)

I thought to seal a mercury switch and put it on the float when
the float goes up the pump comes on (through a good relay)

However the switch comes on the pump runs for a very short time
and just clicks on and off driving the relay crazy.
I need to have a delay that will keep the relay pulled in say
5 to 10 seconds before dropping out and resetting.
Anyone have an idea or circuit that will do this for me.
Thanks
Oliver Fleming

"Meindert Sprang" wrote in message
...

"Vito" wrote in message
...
del cecchi wrote:

"Larry Demers" wrote
... A series cap with the diode seems like a better idea to try.


This is a DC system in the average boat. There is only one polarity
of
inductive kick. Diodes work fine. Capacitors in series with the
diode
wouldn't work at all.

That's odd considering that literally millions of DC automobile ignition
systems used a capacitor in parallel with the "points" to protect them
from the coil's inductive kick. BTW, the "kick" is damped AC.

That has a different reason. Damping a coil with a diode does the job,
since
the induction voltage is ALWAYS the opposite as the originating voltage.
But, using a diode keeps the current flowing while the magnetic field
collapses. This causes a slow collapse of the field. In a coil in the car
(is it called bobbin?) has to produce a high voltage and therefore the
field
has to collapse as fast as possible. Therefore a capacitor is used with
certain value to get the best trade-off between generated high voltage
and
RF interference surpression.

Meindert

The capacitor across the points has its voltage reset to zero when the
points close. The capacitor acts to supress arcing by slowing the rise time
of the current decrease when the points open. The resulting oscillation in
the series tuned circuit is damped by the secondary driving the spark
through the plug.

In the case of the relay coil, there is no secondary. If there were no
diode, the tuned circuit would oscillate for a long time. With the diode,
the inductive kick will be stored on the capacitor and, being unable to
discharge through the reverse biased diode, will stay there for a long time.
During that time the diode will never turn on, due to the voltage on the
capacitor.

del cecchi

Sigvaldi Eggertsson wrote:

The climate of Iceland is not much different from the UK one, maritime
temperate with mild winters and cool summers. You were probably
thinking about Greenland?

I figured it must not be terribly bad in Iceland. Otherwise they would
not be able to grow all those gorgeous women. :-)

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com


I'veheard the rule of thumb esxpressed,
"Geenland is white, but Iceland is green."

"Vito" wrote in message
...
Meindert Sprang wrote:

The small oscillation you get has nothing to do with mass of electrons
and
their inertia. It is caused by the fact that every coil has a bit of
parasitic capacitance, forming a resonant loop with the inductance of
the
coil, ...

Yes but Meindert old bean, if electrons didn't have inertia resonant
circuits wouldn't resonate.

Is this a feeble attempt at humor, or are you an idiot? Sometimes hard to
tell on the net.

del cecchi

Del Cecchi wrote:

"Vito" wrote
Yes but Meindert old bean, if electrons didn't have inertia resonant
circuits wouldn't resonate.

Is this a feeble attempt at humor, or are you an idiot?

Neither one. Do you doubt that electrons have mass and therefore
inertia? If they did not, then current would stop at once when the coil
unsaturated. But it does not. The little buggers keep going til they've
charged the capacitor (parasitic in this case but still real). Then
(Bugle sounds retreat) they head the other way re energizing the coil
..... etc. .... creating a damped AC wave.

Sometimes hard to tell on the net.

Yes indeed.

"Vito" wrote in message
...
Del Cecchi wrote:

"Vito" wrote
Yes but Meindert old bean, if electrons didn't have inertia resonant
circuits wouldn't resonate.

Is this a feeble attempt at humor, or are you an idiot?

Neither one. Do you doubt that electrons have mass and therefore
inertia? If they did not, then current would stop at once when the coil
unsaturated. But it does not.

Sorry to say Vito, but that is completely nonsense. The reason current keeps
folwing for a while is magnetism. Current flowing through a wire creates a
magnetic field around the wire. Also, a changing magnetic field induces
current in a wire. What happens when you open the contact is this: the
current stops flowing, the existing static field collapses and is therefore
changing. And the field change induces a current in the wire in the opposite
direction. In a straight wire this effect is hardly noticable but coiled up,
the field around the wire concentrates and the effect gets bigger.

And if you still believe in electron inertia, I advise you to go and read a
book about basic electric laws.

Meindert

Meindert Sprang wrote:

And if you still believe in electron inertia, I advise you to go and read a
book about basic electric laws.

But Meindert, I weld from time to time and as you probably know welding
requires large current flows. This means huge numbers of electrons are
racing along the wire to the welding rod.

I have noticed that when I pull the rod away from the work it always has
a big blob on the end. Are you saying this isn't because all those
electrons kept rushing into the hot metal and caused it to bulge out
when they had no place to go?

Rick

One atom bumps into another atom.

"Hey! you stole one of my electrons"

"Are you sure"

"I'm positive!"

"Meindert Sprang" wrote in message

And if you still believe in electron inertia, I advise you to go and read
a
book about basic electric laws.

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["Followup-To:" header set to rec.boats.cruising.]
On Thu, 30 Oct 2003 18:49:26 +0100,
Meindert Sprang wrote:
"Vito" wrote in message
...
Del Cecchi wrote:

"Vito" wrote
Yes but Meindert old bean, if electrons didn't have inertia resonant
circuits wouldn't resonate.

Is this a feeble attempt at humor, or are you an idiot?

Neither one. Do you doubt that electrons have mass and therefore
inertia? If they did not, then current would stop at once when the coil
unsaturated. But it does not.

Sorry to say Vito, but that is completely nonsense. The reason current keeps
folwing for a while is magnetism. Current flowing through a wire creates a
magnetic field around the wire. Also, a changing magnetic field induces
current in a wire. What happens when you open the contact is this: the
current stops flowing, the existing static field collapses and is therefore
changing. And the field change induces a current in the wire in the opposite
direction. In a straight wire this effect is hardly noticable but coiled up,
the field around the wire concentrates and the effect gets bigger.

And if you still believe in electron inertia, I advise you to go and read a
book about basic electric laws.


Electrons have mass, ergo, they have inertia. Not much it's true, but
it's there.

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--
Jim Richardson http://www.eskimo.com/~warlock
Some people are born normal, some people achieve normality, and some
have normalcy thrust upon them by a nice nurse with a hypodermic.

Meindert Sprang wrote:

Sorry to say Vito, but that is completely nonsense. The reason current keeps
folwing for a while is magnetism. Current flowing through a wire creates a
magnetic field around the wire. Also, a changing magnetic field induces
current in a wire. What happens when you open the contact is this: the
current stops flowing, the existing static field collapses and is therefore
changing. And the field change induces a current in the wire in the opposite
direction.

But current continues to flow even after the magnetic field has
collapsed. You can prove that with the right instruments.


And if you still believe in electron inertia, I advise you to go and read a
book about basic electric laws.

I did, at Bell Labs - you know the folks who invented transistors, et
cetera. Electrons have mass everything with mass has inertia. Look it up
in any basic physics book, or better yet memorize
http://www.newtonphysics.on.ca/EINSTEIN/Appendix1.html. Exam next
Thursday (c: