On Mon, 26 Jan 2004 14:43:52 -0600, Dazed and Confuzed
wrote:

Keith wrote:

I use a groco air switch. A tube runs down into the bilge and the switch is
mounte 3' away. You can adjust the switch sensitivity to get it to do
whatever you want. It's basically a big diapharam switch like a washer uses
to sense when the tub is full.

--

Keith
__
Adult, n.: One old enough to know better.
"Dazed and Confuzed" wrote in message
...
Any suggestions for a bilge pump switch that will activate at about 1.5"
water level and shut of at less than 3/4"? Of course reliability counts.
I remember that everyone is unhappy with the Rule products.

thoughts, suggestions and experience appreciated

thanks
B



cool. I'll look for them and see if I cam make them work for me...

Again, your problem is not the switch, but the fact that most bilge
pumps will not pump a bilge dry.

"P.C. Ford" wrote:

On Mon, 26 Jan 2004 14:43:52 -0600, Dazed and Confuzed
wrote:

Keith wrote:

I use a groco air switch. A tube runs down into the bilge and the switch is
mounte 3' away. You can adjust the switch sensitivity to get it to do
whatever you want. It's basically a big diapharam switch like a washer uses
to sense when the tub is full.

--

Keith
__
Adult, n.: One old enough to know better.
"Dazed and Confuzed" wrote in message
...
Any suggestions for a bilge pump switch that will activate at about 1.5"
water level and shut of at less than 3/4"? Of course reliability counts.
I remember that everyone is unhappy with the Rule products.

thoughts, suggestions and experience appreciated

thanks
B



cool. I'll look for them and see if I cam make them work for me...

Again, your problem is not the switch, but the fact that most bilge
pumps will not pump a bilge dry.

True, most will not pump a bilge dry. But most air switches that I have seen will
shut of at about 1", and come on at about 3". Most pumps will pump to less than
3/4". I have a flat bottomed shallow bilge. I will accept the short cycles that
this is gonna give me, but I need a switch which will turn on at about 11/2" and
shut of at about 3/4 inch.


--

Don't like the looks of nudists? Complain to the manufacturer.

Keith wrote:

I use a groco air switch. A tube runs down into the bilge and the switch
is
mounte 3' away. You can adjust the switch sensitivity to get it to do
whatever you want. It's basically a big diapharam switch like a washer
uses
to sense when the tub is full.

Commonly known as a "bubbler". Used at one time by the waste water industry
to control pumps in lift stations.

Very old and not very reliable technology which is why is is no longer used
in modern installations.

"Dazed and Confuzed" writes:

Any suggestions for a bilge pump switch that will activate at about 1.5"
water level and shut of at less than 3/4"? Of course reliability counts.
I remember that everyone is unhappy with the Rule products.

The float switch has not been invented that is reliable but it is the only
technology that is low cost enough to sell in the consumer marine market.

There is reliable technology available for this application. Prices start
about $500 USD.

Let me know if you are interested.


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

Lew Hodgett wrote:

Keith wrote:

I use a groco air switch. A tube runs down into the bilge and the switch
is
mounte 3' away. You can adjust the switch sensitivity to get it to do
whatever you want. It's basically a big diapharam switch like a washer
uses
to sense when the tub is full.

Commonly known as a "bubbler". Used at one time by the waste water industry
to control pumps in lift stations.

Very old and not very reliable technology which is why is is no longer used
in modern installations.

"Dazed and Confuzed" writes:

Any suggestions for a bilge pump switch that will activate at about 1.5"
water level and shut of at less than 3/4"? Of course reliability counts.
I remember that everyone is unhappy with the Rule products.

The float switch has not been invented that is reliable but it is the only
technology that is low cost enough to sell in the consumer marine market.

There is reliable technology available for this application. Prices start
about $500 USD.

Let me know if you are interested.

--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

Lew:
let me explore other options first. Price IS an object (I'm cheap) and I think
that I can build a switch cheaper than that. I can, if need be, use a couple of
op amps and make a level sensor. I was hoping to buy a pre made mechanical
switch, but if not.....


--

Don't like the looks of nudists? Complain to the manufacturer.

"Dazed and Confuzed" writes:

Lew:
let me explore other options first. Price IS an object (I'm cheap) and I
think
that I can build a switch cheaper than that. I can, if need be, use a
couple of
op amps and make a level sensor. I was hoping to buy a pre made mechanical
switch, but if not.....


Others have gone before you, but we still sell a lot of switches.

You will never build a reliable float switch. Low cost, yes, reliable, no.

Good luck.

BTW, on my own boat, never have or will have a bilge pump level switch.

Rather, have a Son-O-Lert or equal obnoxious noise maker wired in parallel
with the pump.

You KNOW when the bilge pump is running.

It runs when it has to run, but not unnecessarily.

Gets the job done, is low cost, and keeps the bilge dry.

Works for me.


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

Lew Hodgett wrote:

"Dazed and Confuzed" writes:

Lew:
let me explore other options first. Price IS an object (I'm cheap) and I
think
that I can build a switch cheaper than that. I can, if need be, use a
couple of
op amps and make a level sensor. I was hoping to buy a pre made mechanical
switch, but if not.....

Others have gone before you, but we still sell a lot of switches.

You will never build a reliable float switch. Low cost, yes, reliable, no.

Good luck.

BTW, on my own boat, never have or will have a bilge pump level switch.

Rather, have a Son-O-Lert or equal obnoxious noise maker wired in parallel
with the pump.

You KNOW when the bilge pump is running.

It runs when it has to run, but not unnecessarily.

Gets the job done, is low cost, and keeps the bilge dry.

Works for me.

--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

What do you do when the boat is unattended if you don't have a level switch?
And what do you think about an electronic level switch? a couple of op amps and
some sensors, and a few resistors. Not much to go wrong, and a low power
consumption. of course, oil is an issue, but aside from that, what are the
drawbacks?


--

Don't like the looks of nudists? Complain to the manufacturer.

"Dazed and Confuzed" writes:

What do you do when the boat is unattended if you don't have a level
switch?

Close any open seacocks when leaving the boat for extended periods.

And what do you think about an electronic level switch?
snip
What technology?

Capacitance, hydrostatic, and vibration are all possibilities, and all have
a down side.

Vibration would be my choice since it is not affected by conductivity or
lack of it.

Having said that, sloshing around will be a major problem. Level switches
like steady state conditions.

It's a bigger engineering problem than it's worth IMHO.

Having an automatic pump on an unattended boat can get VERY expensive.

As an example, spring a fuel leak and allow 10-20 gallons to drain into the
bilge, then pump it overboard while the vessel is unattended.

Need I say more?

HTH


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

NOT having an automatic bilge pump can get very messy too.
I "lost" the grease fitting in the stuffing box but didn't know about it.
Pumped out the bilges and blamed someone for not leaving the boat dry after
using it. Just happed to visit 24 hours later- water was over the
floorboards. Made about 5" water in 24 hrs. Another 3" and the bilge pump
outlets would have been at water line, say another 8 hours and she would
have been gone.
I've now fitted a second battery, and a float switch. Bilge pump runs off
the second battery only. Also re-routed the bilge pump hoses to have a nice
high loop to prevent syphoning back into the boat. Next step is an alarm -
I'm considering either time delayed "bilge pump float switch closed" ( to
detect blown fuse, blocked pump or the pump actually running for a long time
...) or separate float switch from the other battery. I've got an old
mercury switch which might make a good alarm. Or perhaps both alarms ....
In comparing the risks of bilge pump pumping fuel leak overboard vs. boat
sinking, I figure that if it sank the fuel would escape anyway.

If fuel leak is a real issue then a bilge pump switch which works on
conductivity would seem the way to go - it should not respond to fuel in the
bilges. But I'd be concerned that conductivity might not work if the
sensing wire got coated by a small quantity of oil and then would not sense
water...

I agree that trying to home develop a reliable bilge pump switch is probably
not worth the effort. But it's certainly worth thinking through the
consequences of all sorts of events - like fuel leaks, switch failure, pump
failure, flat battery etc etc. And "some one else" forgetting to open the
closed sea-cock before starting the engine ...
If the aim is to prevent sinking of the boat, perhaps using a hydrostatic
system connected to a thru-hull is the way to go. This would turn on the
bilge pump if the boat was too low in the water. Leakage of fuel into the
bilges would not be an issue.
My approach is that I'm more likely to lose the boat by sinking than I am to
have a significant leak when the boat is unattended. Hence I'm doing my
best to protect my insurer by maintaining my fuel system and fitting
automatic bilge pump and ultimately an alarm. I've not had this discussion
with the insurer, but I figure I know more about my boat than they do. I
guess I could also turn off the fuel at the tank whenever I leave the boat,
but it's not normal practice around here, and forgetting to turn it on can
have nasty consequences too.

You can get right into this risk assessment / hazard analysis stuff. And I'm
not suggesting that you should not minimise risks and try to engineer them
out. But ultimately if you are not prepared to accept that there are risks
in everything we do, perhaps you should not have a boat ...

David







"Lew Hodgett" wrote in message
link.net...

"Dazed and Confuzed" writes:

What do you do when the boat is unattended if you don't have a level
switch?

Close any open seacocks when leaving the boat for extended periods.

And what do you think about an electronic level switch?
snip
What technology?

Capacitance, hydrostatic, and vibration are all possibilities, and all
have
a down side.

Vibration would be my choice since it is not affected by conductivity or
lack of it.

Having said that, sloshing around will be a major problem. Level switches
like steady state conditions.

It's a bigger engineering problem than it's worth IMHO.

Having an automatic pump on an unattended boat can get VERY expensive.

As an example, spring a fuel leak and allow 10-20 gallons to drain into
the
bilge, then pump it overboard while the vessel is unattended.

Need I say more?

HTH


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the
Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

Lew Hodgett wrote:

"Dazed and Confuzed" writes:

What do you do when the boat is unattended if you don't have a level
switch?

Close any open seacocks when leaving the boat for extended periods.

If you can be so sure that there are never going to be any leaks....



And what do you think about an electronic level switch?
snip
What technology?

Capacitance, hydrostatic, and vibration are all possibilities, and all have
a down side.

conductivity.



Vibration would be my choice since it is not affected by conductivity or
lack of it.

Having said that, sloshing around will be a major problem. Level switches
like steady state conditions.

So put your sensor in a small tube open at the top and with small holes at the
bottom. this will be at whatever the bilge level is, but will more or less
isolate the sensor from sloshing.



It's a bigger engineering problem than it's worth IMHO.

You may be right.



Having an automatic pump on an unattended boat can get VERY expensive.

As an example, spring a fuel leak and allow 10-20 gallons to drain into the
bilge, then pump it overboard while the vessel is unattended.

as likely as any other leak.



Need I say more?

HTH



So what is the method of your $500 solution?




--

Don't like the looks of nudists? Complain to the manufacturer.

"Dazed and Confuzed" writes:

If you can be so sure that there are never going to be any leaks....

I kept my boat on a mooring unattended from Monday thru Thursday, 6 months
out of the year without any problems.

conductivity.

Conductivity is the lowest cost and most unreliable of all the electronic
level measuring technologies. Too many problems with build up on the probes
over time.

So put your sensor in a small tube open at the top and with small holes at
the
bottom. this will be at whatever the bilge level is, but will more or less
isolate the sensor from sloshing.

AKA: "Stilling well" an old and out of date technology abandoned as too
labor intensive to maintain by the waste water industry at least 20 years
ago.

You may be right.

I know I am. 20+ years in the business tells me that.

So what is the method of your $500 solution?

There are a couple of technologies that have a chance.

You could use a capacitance probe that ignores probe build up.

My choice would probably be a vibrating tuning fork. By its very nature, it
ignores probe build up.

Either one of these units would include a build in time delay set for maybe
30 seconds.

The pump would energize after a time delay when the liquid contacts the
probe.

The time delay helps to eliminate splash or sloshing false starts.

When the liquid falls below the contact point, the 30 second time delay
would keep the pump running for 30 seconds.

The alternate to time delays is a 2nd probe.

SFWIW, we provide a 100% money back performance guarantee for every unit we
sell.

We definitely would not be willing to provide that guarantee for this
application.

Maybe this gives you a little better perspective why I consider level
switches in the bilge of a boat a waste of time and money.


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures