An man paddle wheel

PabloPicasso

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I have a navman paddle wheel log. The instrument readout is not reading and the log wheel is spinning. I remember reding somewhere that it maybe the little magnet on the paddle wheel that needs replacing. Anyone got any idea how to get another?

I think madman gear is now obsolete. Unless you know different of course?
 
My reading of the original; post was that he was asking where he could get another magnet.

Maybe, but it's certain that Navman would never have sold the magnet on its own as a spare part. It surely isn't that difficult to source a smallish magnet and chip a bit off with a chisel, etc?
 
Maybe, but it's certain that Navman would never have sold the magnet on its own as a spare part. It surely isn't that difficult to source a smallish magnet and chip a bit off with a chisel, etc?

Or replace the whole unit?
In my ignorance I would appreciate advice on this, because my own log has similar problems. I thought that I'd have to change the whole through-hull caboodle.

Is this a straightforward procedure? And how would I go about sourcing the "bits"? I think mine's an ST40
 
Or replace the whole unit?
In my ignorance I would appreciate advice on this, because my own log has similar problems. I thought that I'd have to change the whole through-hull caboodle.

Is this a straightforward procedure? And how would I go about sourcing the "bits"? I think mine's an ST40

A log transducer is a very simple thing. The flow of water over the hull spins a little paddle wheel. There's a tiny bit of magnet embedded in one of the paddles, and every time it rotates it gives a tiny electrical pulse. The faster the flow of water, the more pulses per second. The speed display turns the pulses into a reading.

If the transducer stops working, it's usually a mechanical problem. Either the paddle wheel has stopped rotating, or the magnet has gone. Both of these faults are easy to detect. If fixing these doesn't work, the problem may be in the transducer itself, but it's more likely to be a cable or connection fault.

If you have to change your ST40 transducer, it's an easy enough job. A new one is about £60. Ideally, you'd need to run the new transducer's wire back to the ST40 display head, because joining transducer wire introduces another opportunity for corrosion and failure.
 
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