How to connect 2 separate nema 2k backbones to a pair of garmin 4208 chartplotters?

[BrightAyes]

How to connect two separate nema 2k backbones to a pair of Garmin 4208 chartplotters?
I have a sailboat with interconnected Garmin 4208 chartplotters. One below at the nav station and one at the helm. I have a Simrad autopilot which uses the Simnet 2k backbone and it is connected to the nav 4208 chartplotter.
I have Raymarine ST60+ wind and depth instruments which are connected to the Nav station 4208 via the 0183 connection.
I am removing the Raymarine instrument s and installing Garmin gwind –GND10 & depth with Garmin GMI-20 & GMX20 Indicators which run on a nema 2k backbone. I would like to feed the wind and speed to the interconnected 4208’s but would like to keep the pwr supplies to the instruments and autopilot separate.
Can I leave the Simrad backbone feeding one 4208 and feed the Garmin backbone into the other 4208?
Will the wind and depth data be on both chartplotters?

[smac999]

you need one of these

http://www.maretron.com/products/nbe100.php

I have used one before to keep a autopilot and nav systems separate on a large network.

[Paul L]

What does separating the instrument power and the AP n2k power accomplish? The AP is separately powered for all its high power needs.

[Neptune's Gear]

Yep, not required. Read the manual for N2K. It needs a bus power supply. It needs a terminator at each end. If the total bus length is less than 100m, then there is no need to have 2 N2K buses. Keep drop cables under 7m and don't dasiy chain devices, but use a single drop cable for each device. Once data is on the bus, any device can use or share it...

If you are pushing the limits of the bus or power draw, there is more too it. Again, read the manuals. The Navico/Simrad/B&G/Lowrance manuals have good sections about N2K.