Anchor Chain Counter: how do they work?

[nigelmercier]

I'm considering making an Anchor Chain Counter using a PIC microcomputer. I've had a look at a couple of commercial models, but I can't see how they get their data on how much chain is out: there doesn't seem to be a sensor, and there is no tach output on the windlass motor.

Any ideas on how they work?

 

[Sixpence]

Most likely it uses a sensor that detects how many times the windlass rotates, probably a magnetic sensor, and it would probably need to be calibrated so that it knows the circumference of the windlass itself to work out how much had been let out

 

[Adamastor]

Pretty much as he says: on almost all the commercial manufacturers' models, there's a reed-switch usually mounted adjacent to the gypsey, with a neodymium magnet on the gypsey itself (which is made of bronze) to close the switch and generate a pulse.
The calibration is usually done by keying in the chain pitch so the length of chain/revolution can be calculated by counting the pulses from the reed switch.
The remote/counters are usually pretty unintelligent creatures which usually only deliver a chain length, so anything which could add valus- say something that reads an NMEA-2k depth sentence to calculate a recommended chain length would be VERY clever...

 

[rogerthebodger]

I have an autoanchor and it uses a hall effect sensor on the body and a magnet in the chain wheel.

manuals here

 

[BobnLesley]

Go on, admit it, this is a Monday morning wind-up isn't it? /forums/images/graemlins/wink.gif You're all just yanking my chain:

...making an Anchor Chain Counter using a PIC microcomputer...

Why? Our boat is quite well endowed with anchor chains; one in the bow locker, one (stern) in the starboard cockpit locker and another (spare/ballast) in the bottom of the bilge. Now I'm no Einstein, but even I can still get up to three without the aid of a calculator. If it's really a problem, then use you fingers to help

Alternatively, if what you're wanting to know how much chain's been deployed, then I've found that paint marks applied at known intervals along the chain, in conjunction with the application of a mark-one eyeball does the job very well and doesn't use any amps either. I accept that with my method you have to walk all the way to the foredeck, but surely you'd be going there anyway to make-off the chain around a cleat and unless you're planning to mount your PC in the cockpit, it'll be instead of a trip below to check the laptop’s screen anyway.

If you are serious, then perhaps you may find some assistance here http://www.gizmology.org/app.html

 

[stephenh]

I have used a remote (cockpit) anchor winch control on a friends yacht and very useful it is - you can anchor single handed without leaving the cockpit, great for 'Med' style mooring.

It has a chain counter and for unknown reasons you can put out, say, 40 m , take it all back in and the reader claims that there is still 3 m out.....

It is a bit of a fiddle getting it back to '0' so you might consider having a zeroing device as part of the program.

 

[gianenrico]

And on some models You can program how much rode to put out and it will control the windlass allowing You to check what is happening around...not silly IMHO