Fixing a log

[tim]

Is there a way of determining whether or not the log paddle wheel is transmitting to the display? The display shows zero all the time and I need to determine where the fault is.
Thanks.

 

[incognito]

Can you withdraw the log? Usually the log is fitted as a simple screw fitting to a tube going through the hull, and you should also have a dummy cap to replace it with - or a rubber bung of the same size, for HAND use only, you do NOT want to break the tube.
Once out, you can check it out by flicking the paddle, and removing any nasty weed or whatever.
One point, when putting back, make sure it is properly aligned - it will be obvious how to do that, and fwd is same as back.

 

[billmacfarlane]

I had the same problem with my ST50 log. When I removed it and spun it by hand , the log registered nothing. The problem was the impeller itself rather than the cable as the new impeller used the existing cable. I don't know of a way of testing whether the impeller itself is transmitting or not.

 

[tim]

Thanks. I've a horrible feeling that I am going to have to replace the impeller. Are impeller fittings the same diameter, or, as is the case with most things nautical, different manufacturers have different sizes?

 

[billmacfarlane]

It all depends Tim. My original ST50 was 11 years old and the replacement was a different size. by the time I paid for the boat to be craned out, paid for the new through hull fitting, and paid for a new impeller it got fairly pricey.

 

[Guest]

What make?
There are two types. Hall Effect and magnetic reed switch. To test magnetic use multimeter on 'ohms' range. For Hall Effect you need to apply a voltage. Too complicated to describe test procedure.
Many different types, designs. some for sail and some for speed. Some one magnet with a counterweight on the opposite blade. Some have more than one magnet.
Have a look at the Airmar site. They make transducers for most of the manufacturers.

 

[Guest]

I have seen this exact problem fixed before. Its a bit of a fuss but the best way to tell if you are getting a signal is to add a clolured LED into the end of the cable. It will flash to show pulses through the cable. This can be done very easily.