No more cheapo float switches

I've found relays to be not that reliable in a marine environment.
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As long as you keep them dry, shouldn't be a problem. I like these -
http://www.ebay.co.uk/itm/12v-ac-dc-Handy-little-Relay-board-ideal-for-security-/110957533328 - nice and easy to connect up, and cheap enough to make carrying a spare an affordable option.

There's only a few reasons why a bilge pump switch can fail - mechanical failure, water leaking into it, or the switch not having sufficient current-carrying capability to handle the load of the pump, and getting burned contacts. I suspect the latter problem is quite common, that's why I'd always recommend connecting the pump via a relay (or Mosfet, as suggested).
 
PilotWolf said:
Can't remember where I saw them or if they were even commercially available but they were based on a washing machine part. It consists of a plastic tube with a pressure sensor at the top. The bilge water compresses the air in the tube and via a relay it turns on the pump.
W.
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Yes, a common arrangement in washing machines and dishwashers. For increased sensitivity use an "air bell", i.e. a short capped pipe in the bilge, open end down, connected by a narrower tube to the air pressure switch mounted somewhere dry.
 
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Thanks guys. For simplicity to fit the existing set up I have ordered 2 'traditional' ones from Seamark. I will consider the water witch type later. I took the completly duff one to bits and there was orrible signs of water ingress presumably from the cable seal or the shaft. I dont think the switch has been submerged more than a couple of times so hardly fit for purpose?
It would be better if the float was lower than the switch so that the switch itself was kept out of the water but, clearly, this would make the device much more awkard to fit.
As stated I have checked them quite often ( hooking my toes under the switch!!) they always worked until the day I came to winterise the boat when both failed, The old sods law in action, made worse by being in mid France with no chandlers in sight!!
 
pcatterall said:
Thanks guys. For simplicity to fit the existing set up I have ordered 2 'traditional' ones from Seamark. I will consider the water witch type later. I took the completly duff one to bits and there was orrible signs of water ingress presumably from the cable seal or the shaft. I dont think the switch has been submerged more than a couple of times so hardly fit for purpose?
It would be better if the float was lower than the switch so that the switch itself was kept out of the water but, clearly, this would make the device much more awkard to fit.
As stated I have checked them quite often ( hooking my toes under the switch!!) they always worked until the day I came to winterise the boat when both failed, The old sods law in action, made worse by being in mid France with no chandlers in sight!!
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My WW just delivered this morning, 2 days after ordering on ebay .£27.48 delivered
It was supplied by Marine Scene, Porthcawl. thats very good service
 
nigelmercier said:
I've been thinking about this. Can someone who has a Water Witch confirm if the electrodes are permanently powered? If it just does a blip every minute or so, I may change my opinion.
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Presumably if the electrodes are submerged, it switches on, an un-submerges them?

I did experiment with a FET based switch, permanently on, but the cheap float switches came along and solved the problem before I'd tested it with rainwater, seawater, oily bilgewater, spilled coffee etc etc.

For most yachts, I maintain that it is much better to sort the leaks at source.
 
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nigelmercier said:
I've been thinking about this. Can someone who has a Water Witch confirm if the electrodes are permanently powered? If it just does a blip every minute or so, I may change my opinion.
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Scan0002-1.jpg
 
lw395 said:
Presumably if the electrodes are submerged, it switches on, an un-submerges them?

I did experiment with a FET based switch, permanently on, but the cheap float switches came along and solved the problem before I'd tested it with rainwater, seawater, oily bilgewater, spilled coffee etc etc.

For most yachts, I maintain that it is much better to sort the leaks at source.
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we have a keel stepped mast,rain water enters via the sheave box`s
 
sailorman said:
we have a keel stepped mast,rain water enters via the sheave box`s
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That can be managed.
Many boats direct water from the mast into the shower drain.
Or you can seal the bottom of the mast and pump it out from there, or plug the mast above deck level, although this is a faff with wiring.

It's worth doing IMHO, it transformed my last boat from a damp to a dry boat.
 
lw395 said:
That can be managed.
Many boats direct water from the mast into the shower drain.
Or you can seal the bottom of the mast and pump it out from there, or plug the mast above deck level, although this is a faff with wiring.

It's worth doing IMHO, it transformed my last boat from a damp to a dry boat.
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we are dry really & have a nice sump of about 15 lts unlike many "flat bottomed" boats. the switch is really a safeguard over the winter period
 
The problem as I see it is that all the bilge switches miss the fundamental point - they should turn on when the water reaches a certain level and turn off once its dropped to a certain level. All the arrangements with a single switch cannot do this so either keep switching on/off rapidly which rapidly wears out pump and switch, the more complex devices have a time delay which helps but may mean the pump runs longer than need be and possibly runs dry. My solution below - btw these switches are available on ebay for about £10 http://www.ebay.co.uk/itm/160804066289?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 though I dont know if they are suitable for marine environment, nevertheless any two switches appropriately spaced would do the trick. Remaining parts available for a few pennies.
 
winsbury said:
The problem as I see it is that all the bilge switches miss the fundamental point - they should turn on when the water reaches a certain level and turn off once its dropped to a certain level. All the arrangements with a single switch cannot do this so either keep switching on/off rapidly which rapidly wears out pump and switch, the more complex devices have a time delay which helps but may mean the pump runs longer than need be and possibly runs dry. My solution below - btw these switches are available on ebay for about £10 http://www.ebay.co.uk/itm/160804066289?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 though I dont know if they are suitable for marine environment, nevertheless any two switches appropriately spaced would do the trick. Remaining parts available for a few pennies.
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i have a Jabsco diaphragm pump in the lazerette,it can run dry.
those impeller pumps in the bilge are very unreliable
 
My last boat had the washing machine pressure switch arrangement, pipe down to the bilge, all connections up in the dry, very good. This boat has a switch in the bilge, don't know the make, it has a horizontal tube with a reed switch inside, a hinged tubular float below with a magnet. It has needed repair once in 20 years, but it only runs the bilge alarm, so low draw may be the reason for long life.
 
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