making a cheap bilge alarm

Csail

Csail

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After a mobo went down on the YC pontoon i thought about a cheap and easy way to alert passers by if the boat did start sinking. Is there an easy way to connect a siren to say a bilge buddy or other water detector? If we had been 10 mins quicker we could have saved that boat.
 
pretty easy tp wire up a siren / sounder to a float switch. however make sure the alarm float switch is higher than the bilge pump switch, wouldnt want the alrm going off just because the water isnt high to have activated the pump yet.

With modern voice recorder chips it would be pretty easy and cheap to have an alarm that mot only made a noise but also shouted out 'high water level in boat, please contact xxx'.

Anthony
 
I knocked up a little circuit to turn on a very loud piezo siren when the bilge pump runs on auto for more than 3 minutes. I've always had a fear of a small leak while motoring and you'd never know that the pump was pumping.

I did the design and build as my project for my amateur radio licence, so killed two birds with one stone. I just used a dual 555 timer (=556 or two 555s), a drive transistor and a relay with some padding on the inputs. Lots of 555 circuits online, and very easy to make work, the 555 is a very forgiving chip. Go for the CMOS version for low standby current and ensure the drive transistors are off when the alarm is off - i.e. close to zero current on standby.
 
Daughter had problems at Uni with water coming in a window (and onto a desk with computer). Got a small kit from Maplins which sounded a high volume alarm when it got wet.
 
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Can be done with a cheap smoke alarm I believe.

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I have one of those fitted right now ...

Get one that has the Test button that you press and hold for a few seconds and the alarm sounds ...

All you have to do is solder a length of twin flex .. I used speaker wire ... one lead to one side of switch ..... other to other side ... now take end of flex .. bare about 1" of each lead ... bend apart ... so they are well away from each other in a Y shape ... dab of epoxy or hot-melt glue to fix in place in bilge. Works a treat ... test occasionally by touching two ends together ...
If you want ultimate luxury - you can even fit a switch in the line .....

It still functions as a smoke alarm as well ... I forgot this when I first mounted it in cockpit and my engine decided to smoke a bit more than usual !! So shifted it to inside locker ... !!

Another has mentioned Maplins .. they do very good water alarm modules that you can add extended lead to - the best though were the bath alarms with a length of flex to the sensor pad - a fancy version of my smoke alarm contacts .. but sadly maplin don't sell them anymore. I lost mine somewhere in my hobby room ... when I do a tidy up it will probably appear by magic !
 
Good old maplins do a water senseing kit. which has got its own alarm included....just a couple of quid... it dosen't use float switchs either. Just a thought! maplin code VX97F yes I have used one (not on the boat) and it works well and cheap...flip at that price a give away
 
Yep - installed a home-made one when I did my recent refit with a (non-float switch) level sensor - don't forget to include a warning lamp that can be clearly seen from outside the wheelhouse by any good Samaritans. Direct battery connection like the gas alarm.

Now if only I remember to switch it on ....

bilge1cy5.jpg

bilge2ei3.jpg
 
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Good old maplins do a water senseing kit. which has got its own alarm included....just a couple of quid... it dosen't use float switchs either. Just a thought! maplin code VX97F yes I have used one (not on the boat) and it works well and cheap...flip at that price a give away

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These are very good ...

Just a pity that Maplins stopped selling the Bath Water alarm ... similar idea with a nice case, 2m lead to a small contact set .... was same price !

Have found similar elsewhere with remote lead - but prices are way higher.

Another use for the water alarms .... filling FW tanks .... it's actually what I bought my Maplins one for ... trouble is I put it down in my home-workroom .... now can't find it !! the alarm that is.
 
I connected a 12 volt buzzer (Maplin) and an led (Maplin) accross the bilge pump or from the switched side of the bilge float....Led and legend tells you witch bilge pump is running after when the buzzer has frightened you to death.....

Nice and simple...loud enough to wake you from any booze induced sleep
 
That's a much better and safer design concept to the Maplin conductivity probe which could false alarm easily. I have gone one stage further and put a delay-on timer before the buzzer (I designed my own electronic one but you might find a kit) so that the buzzer only goes off when the bilge pump has been running for longer than a preset time - e.g. 45 seconds.

This way, if you have an early leak in a hose, or whatever, which the pump is coping with (so the bilge level does not rise much at that stage), the alarm goes off. Thankfully mine has never gone off but when I am motoring I am very glad to know that it is in-circuit.

Worst case, with my system, you get a 45 second delay in the alarm sounding which isn't much in the grand scheme of things.
 
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