Crimped lead to raymarine st60 speed transducer

[Banooma]

Hi,
My knotmeter has been reporting 0.00 for some time, so I pulled out the transducer. The paddle wheel may very well be compromised as it was filthy, but I also see the lead wire sheeting is crimped and cut. The positioning and size of the transducer make for a bad fit under the floorboards, and it was probably stepped on a few times. I was trying to find a schematic to open it up and try re splicing and reconnecting, but want to know that is doable first. Is it salvagable, or would an injury to the shea thing normally grounds for replacement?

 

[Ralph Johnstone]

The logical thing here is to clean the transducer first, spin it, and see if you get a reading.

THEN continue on to deal with the lead wire shielding. A small cut as you describe should not affect the signal.

 

[Banooma]

I felt that from research I'd done, that the paddle wheel would be removed to be effectively cleaned, as it had not been done in years, if ever. I did spin and got no reading for a max speed. Since I was alone, I had no way of knowing whether the instrument displayed anything greater than zero when it was actually spinning. I had brought some tools to try to remove the wheel, but the pin and pin hole were narrower than my smallest nail punch or nail. Since wire was also exposed, I thought it best to ask the question so I'm armed with two potential solutions next time I have the chance to work on it.

 

[Captain Larry-DH]

Those wires can be re-spliced without issue. If you have a smart phone you can prop it in front of the display and take a video while you do the spin test. (I also use this video technique to “see” behind things when I can reach but need a visual.)

 

[Ron20324]

To clean the paddle wheel and housing, get a grout-cleaning brush or somethink similar. It's like a long-bristle tooth brush. Soak the wheel for a day if you can wait. Then move the brush as the wheel moves, rinse. you can do it again, but hold the wheel with thumb while you scrub the wheel and housing. Rotate the wheel to clan as needed. I always spray some lube in the wheel and recess to lube the axle pin. Sorry, but it takes two to spin the wheel and watch the readout.

 

[John T1594]

The RayMarine speedo on my 2000 H340 went bad a a few years ago. I ordered a # RAYE26031 ST30/ ST60 transducer from Boatersland (http://www.boatersland.com/raym78713.html)and spliced it into the current wires from the thru hull. The new transducer fits the thru hull. Raymarine also suggested that I contact GEM ElectronicsCo., the maker of Airmar transducers at 803-693-0777 to get their recommendation on replacing the transducer.

RayMarine advice on Testing the Speed Sensor:

Verify that the transducer’s paddle wheel is free of marine growth and rotates freely on its shaft
Power down the instrument
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 paddlewheel 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 functional. If not, then the transducer has failed and should be replaced.

The paddle wheel should have magnetic arms and can be checked.

Also, water may enter the transducer and damage the electronics. Raymarine says to let it dry out for 24+ hrs and recheck for function as above. “O” rings must be intact.

It was almost impossible to route any wires from the speed &/or depth transducers to the cockpit as the wire runs are tortuous and inaccessible. I just spliced the new wires into the old and it worked perfectly.

 

[Hello Below]

Sorry, but it takes two to spin the wheel and watch the readout.

Not necessarily. The use of a video camera/device (iPhone, iPad, Android, GoPro) pointed at the display while one spins the paddle wheel will do the same. Also the ST60 Speed has a page that records the maximum speed since the transducer was last powered up. When the instrument is turned off then back on the maximum speed will be zero. Rotate the paddle wheel and if the transducer is working the maximum speed will be something other than zero. Also here is an old post about splicing transducer cables.:

Airmar Inline Cable Splice