Our through-hull knot speed transponder has stopped providing accurate readings. When removed and inspected, the wheel is clean (we remove it when not in use) and spins freely, but knot readings continue to be variable and stuck in the 1-3 knot range and not related to our actual speeds. The bottom of the hull is clean. Where would all of you start troubleshooting? Thanks in advance for your experience.
—
Sandy Paige / Meg Arnold
"Shenandoah"
C36 2000
Emeryville, CA
You might try this testing proceedure then calling Raymarine Service in New Hampshire (EDT) with the results. Good luck on getting them as their service is usually deemed as 'unacceptable' but it is hard to trouble shoot an instrument problem over the phone without any information. I have better luck when I call in the early morning.
Testing an instrument speed through water transducer
Testing an instrument speed through water transducer
The following procedure may be used to testing an instrument speed through water transducer:
- Verify that the transducers paddle wheel is free of marine growth and rotates freely on its shaft
- Power down the instrument or iTC-5
- Disconnect the GREEN and SHIELD transducer leads from the instrument display or instrument pod.
- Connect a multimeter to the GREEN and SHIELD transducer leads and configure the multimeter to measure continuity or resistance.
- Slowly rotate the transducer paddle wheel by hand. Note that as the paddle wheel is rotated, the multimeter should alternate between an open circuit and a closed circuit with each quarter turn. As such one complete revolution of the paddle wheel should open and close the circuit four times.
Should the multimeter respond as indicated above, then the speed sensor element of the transducer would be deemed operational. If not, then the transducer has failed and should be replaced. I'm guessing this is an ST-4000 unit ? and the paddle wheel sensor is shot.
There are also several Raymarine Forums on Facebook. You may want to ask those folks if anyone has seen this problem before.
Bill
Bill Dolan 1990 Catalina C-36 MKI - Hull #1041 'Williwaw'
Std. Rig, Walk Through, Wing Keel
M35, Oberdorfer Conversion,
Home Waters; Charlotte Harbor & The Gulf Islands of Florida
'You are never out of work if you own a boat'