ITC-5 depth issue

[kdg_dean_austin]

Hello,

I've searched the forums and haven't found anything quite like this problem, so I'm going to start a new thread.

We have a 2001 Beneteau 361 sailboat originally installed with Raytheon/Raymarine instruments - ST60 TriData, ST4000 autopilot, ST60 Wind, and ST60 Graphic Repeater down below. Charting was provide by a hand-held Lowrance device, not integrated into the Raymarine equipment at all. In 2010, right before departing Rhode Island for Florida, the ST60 TriData developed an odd problem where the SeaTalk portion of the device caused problems for all the other devices on the network. After debugging it with a local marine electronics guy, we "solved" the problem by cutting the SeaTalk wire in the connector from the ST60 TriData (effectively isolating it from everything else), which allowed the other devices to work correctly, though without depth information. The ST60 TriData device continued to provide depth info just fine, so we proceeded to Florida without incident.

Two years ago, I decided to begin updating the electronics. We added the iTC-5 to use the existing transducers; an i70 display in place of the ST60 TriData; a SeaTalk 1 to SeaTalk ng converter to supply the transducer info to ST4000 autopilot, the ST60 Wind and ST60 Graphic Repeater; and an A65 MFD centerpiece to the whole thing. It has all worked great, except for one thing - the depth being reported periodically surges from the correct value up to about twice the value, then wanders back down. Literally, I'll watch the i70 show the correct value of 6.2ft (for example) then over a period of a few seconds, the depth will climb to 13ft, hover there for a second or two, then just as quickly come back down to 6.2ft. I'm stationary, in my slip, just watching it. The boat isn't moving at all. Watching the depth on the A65 MFD, I see the exact same behavior. To prove that it isn't the transducer, I put the old ST60 TriData back in and put the leads from the depth transducer back in and the depth is correct, rock solid, no real variation. This system has exhibited this behavior for the last year-and-a-half, whether underway or docked, in deep water or shallow, going fast (okay, not really fast - it is a sailboat), or at idle speed - I even recorded a video of this weirdness. I've tried to see if there is a calibration, but I can't find anything that might adjust that. I'm out of ideas.

Here is another data point - about two weeks ago, I replaced the wind transducer at the top of the mast. It was an old mast head unit with the cylindrical pod with the new egg-shaped mast head unit. I connected the instrument leads directly to the ST60 Wind and recalibrated - everything was fine. Today, I connected the wind transducer leads to the iTC-5 and wind data started appearing on the i70, the A65 MFD and the ST60 Wind (through SeaTalk), so I was happy. As I stood there and watched, however, I watched the wind speed suddenly begin to increase, as if a significant gust just blew up, then subside, as if the gust passed. Now, granted, the transducer is 50 ft up from where I was standing, but I didn't see any evidence of a gust. As I watched, this continued to happen several time. To me, it sure looked like the same surging behavior, but with the wind speed instead. What is going on?

Help! :)

Thank you,
Dean Thomas
2001 Beneteau 361 Second Wind
Cape Coral, FL