autohelm st -50 knot meter

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E

ed cortese

When I pull the autohelm st-50 transducer out of its hull fitting and spin the paddle with my fingers, I get a reading at the steering post pod. When I replace the transducer back in the hull fitting and boat (1995 Catalina '36 mkll) begins moving through the water, get no reading at steering post pod. Paddle wheel is absolutely clean: no weeds, gunk, barnacles, etc.; transducer arrow pointing dead ahead; and transducer pushed through fitting as far as possible. Any help before I'm told to replace the entire unit? Thanks...
 
R

Ron

Ed....

Perhaps this seems silly, but have you had a "volunteer" go below an spin the wheel to see if you get an instrument reading ? Maybe it is almost turning 360 and then binding on something not obvious.
 
C

Chris Burti

Try once more

I sometimes have the same problem on my C-320 with ST-60 instruments. If I repace the transducer by making sure it is centered, push down very hard and then screw the cap down tightly as I can by hand...it works. It sometimes takes me two or three tries. I suspect that even a little algae on the hull prevents proper operation unless the transducer is fully down.
 
Dec 3, 2003
2,101
Hunter Legend 37 Portsmouth, RI
Speed TD

Remember that the paddle wheel must turn freely. If there is any binding at all, it will not function. The yard may have lifted the boat and had the straps over the paddle wheel and bent the axle on it. Spares are easy to replace.
 
G

Gary

dirty hull

I had the exact same problem. Cleaned and cleaned the impeller. I could spin it by hand, get up climb the companionway and see it still reading 10kts. Finally asked my diver to take an extra look around the impeller. SUCCESS, something was down there (he didn't remember or know) but its been good since. Gary H320
 
Jun 4, 2004
122
- - Long Beach, NY
Is it on the centerline

Silly question, but has it ever worked? Raymarine recommends that it be installed as close to the centerline as possible. If not you will not get a good flow of water over the wheel. Just a thought.
 
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