Topic: Which cables to link units?

[muskybrad47]

So, I'm looking to add another HB to my rig, finally.  I have a 987csi with weathersense now and I'm looking to add a 998csi. Now, I see there's lots of different cables and ways of linking them up. I'm wondering what is the best way to do this and which cables do I need? I understand the 987 is not eithernet capable and is it better to run 2 GPS for faster mapping? From what I've read, I need AS- interlink, some y cable and an extension cable? Any help is appreciated so I can order everything at once and not have any surprises or confusion of what to do when it arrives. Cool site!

[Roddy]

Only one GPS reciver is all you will need, if two gps ant are used ONLY one will be used by the units.

Roddy

[Humminbird_Greg]

Not so Roddy.  It all depends on how you have the GPS Receivers and units connected.  Most of the time you have the ability to select which GPS Receiver each unit will use.

Muskybrad47,
I would not even try to InterLink the 987 unit to the 998 unit.  The last software that was released for the 987 unit was version 4.770.  For the InterLink to work properly, both units have to be running at least version 5.310 software. 

If each unit is running its own GPS Receiver than each will be able to get 4x faster updates from the GPS Receiver.  Using a GPS Receiver through an InterLink slows this to one update per second.

[muskybrad47]

Thanks for responding Greg.  Can I link them with AS- syslink or am just out of luck with this 987?

[Roddy]

Greg; My bad! I was thinking of brand G#@^%n on brad change.

My Bad Roddy

PS: I have a 947,987 and 1198 running off one (1) -50 GPS rec ant and no interlink. Works great!! RJO'C

[Humminbird_Greg]

Muskybrad47,
Yes you can connect both units to one GPS Receiver using the As-SysLink cable but all they will do is share use of the GPS Receiver – no data will be shared between the units.  The upside of this is that both units will be getting the 4x GPS updates.

Personally I would install a GPS Receiver for each unit for two reasons:
Reason 1: When marking waypoints that are sonar based each unit assumes that the GPS Receiver and transducer are at the same location.  If they are not than you will be introducing inaccuracy to the waypoint coordinates.  Depending on your boat heading at the time you marked the waypoint and the heading when you come back looking for it again; you could be off by as much as 2x the distance difference between your GPS Receiver and transducer.  This is of course in addition to the GPS Receiver’s accuracy.
Reason 2: Having two GPS Receivers on board gives you one as a back up just in case one decides to quit working in the middle of a fog bank…

[muskybrad47]

Roddy, are your units sharing waypoints? If so, how do you do it?

If I can't share info with this 987 then it defeats the purpose of me adding the new one and buying two new units is out of the question.
Thanks for your help guys

[Roddy]

Musk; No my set up is for GPS ONLY, not waypoints,tract,ect interface.

I use three HB units,each has a single function.
    947-NAV and tow fish terrain avoidanse.
    987-tow fish tracking.
    1198-tow fish and tm xducer.
    interphase twin scope-terrain avoidanse.
Only the GPS interphase between the units.
I do save nav data on the 1198.
Things can get a little bit fast pasted some times!!!

Roddy