Knot Meter Problems

Previous topic - Next topic

0 Members and 2 Guests are viewing this topic.

reedbr

I just installed my Autohelm brand knot meter transducer for the first time this year.  I had it completely cleaned off and spinning free.  I them immediately used the boat for a straight week and found it to work only 25-50% of the time.  At first it read very high (7 knots when we were doing 4), then I found the calibration was set to 2.5x.  I reset the calibration to about 1.3 and then it died again (reads 0.0).  Each day it worked some part of the time, usually more at lower speeds than higher speeds.  Sometimes it worked in the morning, sometimes in the afternoon.  The through-hull seems to have a single notch, so I can't believe that I have it installed at the wrong angle or backwards.  The sea tempurature always reads OK, so at least some part of it works all the time.  The transducer is in the port bow, about 6 inches up from the centerline and opposite the depth finder.  It looks like a standard factory or original comissioning installation.

What part do you think I should troubleshoot first?  Any help is appreciated.

Brian Reed
1997 C34 mkII "Ambitious"
Solomons, MD
Brian Reed
1997 C34 mkII "Ambitious"
St. Mary's River, MD

Mike Smith

Is the unit linked through SeaTalk to other units, or is it stand alone, and have you calibrated it on a known distance course this season?  I had a similar problem last month and solved it by turning the unit off, then back on again.

Mike and Jan Smith
S/V Breezer
www.mikejansmith.com

reedbr

Mike-

I know the unit is SeaTalk capable, but don't know how it is wired.  There was an early GPS that came with the boat, also capable of interconnection (NMEA, SeaTalk or something like that) but I have no indication that it was wired all together.  Nor do I have any idea how to figure that out.  I guess maybe my first step is to pull the knot meter display and disconnect all wires except power and tranducer and see if things change.

I attempted calibration against GPS to get close, however, it is hard to calibrate when it goes to 0.0 knots so frequently.

Ron-  You think the unit would still be under warranty after 6+ years and three owners?  I'll have to check on that.

Any other ideas I would like to hear them.  Thanks.

Brian Reed
1997 C34 mkII "Ambitious"
Solomons, MD
Brian Reed
1997 C34 mkII "Ambitious"
St. Mary's River, MD

Still a Thrill

Brian,

I just went through the same problem on my C36 #765.  I have the ST60 Tridata instrument (All Raymarine Instruments with Seatalk) and the speed would work sporatically and then finally just read 0.0 all the time. I contacted Raymarine and they told me to check the transducer to see if the magnet was still working by placing a screwdriver next to the paddle wheel and to make sure it was not fouled. They also asked me to make sure that all of the settings where correct, it was the master and not the slave. The other suggetions was to see if I could set it to use the SOG from the GPS.  I could not get it to accept any input from the GPS (RayChart 320). All of the test said that something was wrong with the transducer, so I bought a new one(Part #243,$70) and now everything works and I can set the speed to SOG.

On the Raymarine.com site they do have a couple of questions and answers posted for trobleshooting the transducer (look under Find Answers in the Customer Service Section).

I hope this helps.

Ralph
S/V Still a Thrill

Roc

Last season, my transducer would also work sporadically.  I cleaned the gunk out and it would work for a short time, then read 0.0. Since the paddle wheel was clean, but still didn't work, I figured it might be the head.  To check if the head was operating, a local marine supply shop let me borrow a new transducer.  I plugged it into the back of the head and everything worked perfectly when I spun it with my finger.  I figured it was the transducer, so I went ahead and bought the new one.  When I went to pull the original transducer out of the thru hull, it broke right in half!  I was holding the top half, and the bottom was stuck in the thru hull.  I managed to push it through, so now it's sitting in the sand at the bottom of my slip.  Apparently, the transducer is made in two halves and water was making its way into it causing it to malfunction.  When I looked at the top half, there was corrosion inside.

So maybe your problem is a transducer that is starting to get weak where the two halves are snapped together, letting water in.  Mine was only 3 years old. I called Raymarine, but they said they wouldn't honor any warranty claim.  I was surprised to see that the transducer is merely snapped together instead of the two halves permanently welded with waterproof adhesive.

Roc-
Roc - "Sea Life" 2000 MKII #1477.  Annapolis, MD