Interfacing Yamaha F-150 to a70d MDF

[pacsport220]

Hello,
I'm new to the Forum and new to marine electronics.
I purchased a 2007 Hewescraft fishing boat here in Washington state, which came equipped with a 2005, Yamaha F-150 main engine and a vintage, Raymarine a70d, Chartplotter/Fishfinder. Until recently I was able to view engine parameters on the a70d. Now, with the F-150 running, the digital gauge images appear without data.

In tracing out the wiring from the F-150, it appears that the previous owner simply cut into and spliced wires from a short, Yamaha Pigtail Bus Wire from the F-150, directly to a Seatalk(ng) Starter Kit Spur Cable. He then joined the Spur with a Tee Connector to a Seatalk(ng) Backbone Cable which connects to a Raymarine 5 Way Connector receiving 12v power, a Spur Cable from the Seatalk(ng) port on the a70d, and the Seatalk(ng) Backbone Cable.

This setup worked for 2 years, but I've since read the sections on the Forum shown below. And, I now realize this was a "work around" circuit design.

Can you please explain why this setup worked at all in the first place?

Also, it appears that to connect the F-150 to the a70d, or any other MFD, correctly, I require the following:
-Yamaha Pigtail Bus Wire
-Yamaha Multi-Port Hub
-Raymarine Yamaha Command-Link Puus Cable
-Raymarine ECI-100 Universal Engine and Control Interface
-Seatalk Spur Cable to join all of this to the existing 5 Way Connector behind the helm.

Is this correct?

Thank you.
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(Excerpts from Raymaine Forum by Chuck, Raymarine Moderator, 1/12/2017).
" When interfacing Raymarine equipment to a NMEA 2000 engine(s), the Raymarine equipment must not be interfaced directly to the engine manufacturer’s network backbone. Instead, the engine manufacturer's network backbone must be interfaced to the engine manufacturer’s NMEA 2000 gateway (ex. Raymarine ECI-100 Engine Gateway, Volvo engine gateway, Yamaha engine gateway, Maretron J2K100, SmartCraft to NMEA 2000 Gateway, Fox Marine MEFI-1/2/3/4, Actisense EMU-1, Noland RS11, etc.), should one be available."

"The primary function of a NMEA 2000 engine gateway is control the flow of data between the engine system CAN backbone and the SeaTalkng/NMEA 2000 backbone used by the marine electronics. The second function of a NMEA 2000 engine gateway is to isolate the power on the engine system backbackbone from power on the marine electronics SeaTalkng/NMEA 2000 backbone. Raymarine’s ECI-100 presently supports integration with select Volvo, Yamaha, Yanmar, Honda, and Caterpillar marine engines.)"