Wiring/Testing Knotmeter

[MomentSurf]

I finally got around to fixing the old Kenyon Knotmeter in my paceship py23. The knob in the back was a bit hard to get moving but with a little bit of WD-40 it got going.

My questions are:

1-Does anyone know how its supposed to be wired? I'm assuming the spots labeled + and - are from the battery. Then the spot labeled SH is the shield wire coming from the little through hull wheel and the spot labeled CT is the inner wire. Is that correct? Is there something that should be at the last spot that isn't labeled?

2-What does the dial do? I know its labeled ON and LIGHTS, but why does it seem like its adjustable? Is the knotmeter always on?

3-Is there a way to bench test it? Also, is there a way to test the thru hull mounted wheel (transducer)?

Any help would be MUCH appreciated!

 

[Silvertip]

Re: Wiring/Testing Knotmeter

You are correct regarding the wiring. You can bench test the entire setup easily. Hook it up and spin the paddle wheel (gently). The knob seems variable because it may have an adjustable internal light. Too much light at night can mess with night vision so instruments typically are not brightly lit and generally are red in color. The meter would not/should not be on all the time as it would drain the battery eventually. You have two other features on this gauge. The 10/5 toggle switch lets you switch the scale so it would read 5 knots at full scale -- obviously for times when you are barely moving. The adjustment on the right, although I'm not positive, appears to be a calibration adjustment.

 

[MomentSurf]

Re: Wiring/Testing Knotmeter

Thanks. For some reason, when I hook it up to 12volts...it pegs the needle once I turn it on. Weird. It does this even when the transducer isn't connected. Maybe I'll mess with that calibration adjustment...

Any sugestions??

Thanks again.

 

[pvanv]

Re: Wiring/Testing Knotmeter

Did you ever resolve the knotmeter repair?

I have a Kenyon knotmeter here, and need a paddlewheel transducer for it. The coax is damaged near the transducer, and the copper shield is that familiar green corrosion. The coax is ordinary RG-58, about 3 or 4 feet long, with a BNC connector on the end. I was unable to get any voltage readings from the paddlewheel, even without the meter connected. So far, I have not found a supplier. But since the boat also has (working) Kenyon wind instruments, and the knot meter is the "heart" of the instruments, I'd like to repair or replace the paddlewheel transducer.

 

[jhebert]

Re: Wiring/Testing Knotmeter

I don't have any precise knowledge of this system, but my impression is the paddlewheel speed sensor probably worked on the principle that a small rotating magnet imbedded into the paddlewheel element induced current into a stationary coil that was placed near it in the mounting fixture. The output signal from the speed sensor was probably a small pulsating current. The frequency of the pulsing current would be proportional to the boat speed. The display unit is a type of frequency meter which measures the rate of those pulses against time, and develops a current to drive the dial pointer meter.

I recall that an older sailboat we used quite a bit had one of these instruments, but I am afraid I do not have any documentation or schematic diagram for it.

If the sensor operates as I speculated above, you should be able to measure the resistance of the pick-up coil. If the speed sensor shows no continuity (an infinite resistance), it would imply the coil had failed. Again, this is assuming the device operates as I speculate. That may be completely wrong. However, given that there are only two conductors going to the speed sensor, I can't imagine there could be much more going on electrically inside the speed sensor.

 

[pvanv]

Re: Wiring/Testing Knotmeter

Yes, and it appears that the paddlewheel is bad. I'm looking to get a new paddlewheel transducer, but so far, can't find a source of supply. Anyone know where to get a Kenyon paddlewheel?

Since the Kenyon knot-log is the heart of the whole instrument setup, I'd prefer to fix just the paddlewheel. Otherwise, I will probably have to get a whole new masthead wind vane and anemometer setup as well.

Spoke with the last company to make parts (in Jacksonville FL), and alas no more parts at all.