The NMEA2000® Standard does not allow daisy chaining for a number of reasons. Most importantly, daisy chaining can setup potential electrical and signal properties mismatches.
First, the NMEA2000® Standard built and maintained by members of the marine electronics industry. It is also an IEC Standard (61162-3). The NMEA2000® Standard states that: "Multiple non-isolated NMEA2000® connections allowing the network backbone to pass thru the device are not allowed." Click here to continue reading.
NMEA2000® Approved Internal Wiring Diagram vs Daisy Chain (Drawing #1)
NMEA2000® Simple Network Designs vs Daisy Chain (Drawing #2)