Author Topic: 788CI DI GPS  (Read 138 times)

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Offline Dusty-Pants

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788CI DI GPS
« on: February 07, 2018, 11:14:05 AM »
I have 788CIDI unit running Version 7.680 mounted on the bow. Standard transducer mounted on Minn-Kota Maxim 74. At slow speeds, while running trolling motor to work around waypoints, I loose my directional arrow or it points the wrong way and I have to speed up to get it and me back on track. This is quite frustrating. Is there any way to get this unit to update with more accurate information?


Offline rnvinc

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Re: 788CI DI GPS
« Reply #1 on: February 08, 2018, 06:16:12 AM »
I have 788CIDI unit running Version 7.680 mounted on the bow. Standard transducer mounted on Minn-Kota Maxim 74. At slow speeds, while running trolling motor to work around waypoints, I loose my directional arrow or it points the wrong way and I have to speed up to get it and me back on track. This is quite frustrating. Is there any way to get this unit to update with more accurate information?

You can add the AS GPS HS antenna accessory which has an internal magnetic compass to show boat heading at all speeds  ...

https://www.humminbird.com/Products/AS-GPS-HS/

Rickie

Offline Dusty-Pants

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Re: 788CI DI GPS
« Reply #2 on: February 08, 2018, 01:54:52 PM »
I checked it out on you tube and it looks like that should solve the issue. Thanks for the info.

Offline Dusty-Pants

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Re: 788CI DI GPS
« Reply #3 on: February 15, 2018, 10:58:27 AM »
Just thinking out loud here, if I replaced my 788 bow unit with Helix 9 DI Mega G2N with a real TM transducer and put the 788 at the console with the 798CI SI. Would the 9 provide accurate slow speed position without an external antenna? Also I am having serious interference with 788 std transducer mounted on TM. Potentially would the 9 solve both the problems I am having with the 788?

I currently have to 798 and 788 interlinked. Could I additionally network the 9 and 788?

If the above does not work what 788 TM transducer would I need to eliminate the TM interference?

Offline rnvinc

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Re: 788CI DI GPS
« Reply #4 on: February 15, 2018, 07:26:24 PM »
Losing the directional icon on the Chart view (due to slow speed) is a function of the inherent error in civilian GPS (which is spec-ed at 8-10ft 95% of the time for HB GPS antennas)  ...

What this basically means is  ...If the boat is not moving "far enough" between GPS data samples from the satellites = the GPS can't tell you've actually moved  ... So the directional icon on the Chart view changes to a circle as the GPS waits for more data  ...

This issue in slow speed GPS function is noted in all HB units with any GPS antenna that does not contain the magnetic compass as in the AS GPS HS antenna  ...

Because the magnetic compass in the AS GPS HS antenna is a function of "magnetic North" - and not a function from GPS satellite data = the AS GPS HS antenna allows the directional icon on the Chart view to show direction at all speeds  ...
-----

Any of the HB xducers designed for trolling motor application have extra shielding to help with possible RFI issues  ...

All HB units come packaged with transom type xducers - but can be exchanged for a TM xducer as long as the included transom xducer has not been used / nor the xducer mounting hardware bag been opened  ...

https://www.humminbird.com/faqDetail.aspx?id=1479

Rickie
« Last Edit: February 15, 2018, 07:29:56 PM by rnvinc »


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