BTW on TZT2 does not match BRG on FI-70 - why?

[JordanBigel]

I have a new system which includes a TZTl12f (TZT2) and several FI-70 instruments.

Last week I finally got a chance to try out the new system for real, on the water on an extended passage. What I find is that the TZT2 consistently shows the bearing to waypoint 1 or 2 degrees "higher" than the bearing to waypoint displayed on the FI-70. If the TZT2 shows the BTW IS 110, THE FI-70 WILL SHOW 109 OR 108. Huh? This seems wrong if the entire network is all sharing data properly.

On the TZT2 this is labeled as BTW-M and on the FI-70 it is labeled as BRG-M - but as far as I can tell from the documentation, both are the bearing to the currently selected waypoint (selected on the TZT2).

After covering about 200 miles, I found that consistently, the TZT2 shows the bearing to the selected waypoint was 1 or 2 degrees higher than what is displayed on the FI-70.

Note that the system uses an external GPS (Garmin) on the NMEA2000 network, not the GPS built into the TZT2 (the TZT2 is mounted indoors and has no reception, I do not have a GP330B either, just a generic Garmin GPS).

Any idea why this is? It's kind of annoying. Which one do I steer to?

Thanks in advance,

Jordan.
S/V Queen Jane

 

[YachtyBoy]

The TZT2 BTW-M value is not the right value because when it has a go-to or an active waypoint, the number value is also in decimals which the TZT2 rounds the number but not to the correct tenths. The FI70 drops the decimal but it does round the BRG-M to the right tenths and is displaying the correct value number. So to answer your question, the FI70 is the correct bearing number.

 

[JordanBigel]

That's along the lines of what I expected - they use different software and use different rounding algorithms, if I could summarize your statement.

Is there some reason (you know of) why Furuno doesn't fix this in the TZT2 software? Seems like an accident waiting to happen, although yeah, 1 or 2 degrees -- I guess its easy to understand why people would just shrug and say "whatever." But I can't believe this has not come up already, and why aren't more people affected by this "encouraging" Furuno to do something about it? I cant be the first person to notice this...

 

[Johnny Electron]

Seems like you just might be the first to report it. Searching the forum, I see no other reports. I will let Japan know and I am sure they will look into it.