This looks interesting, quite a comprehensive software tool for designing nmea2k networks.
" would be handy if it just let you easily mock up a proposed network. But it does much, much more than that. As you drag and drop cables, connectors, and devices, the software keeps an eye on total cable lengths, amperage loads, and the resulting voltage drops, and alarms you if you're over the limits. It also keeps track of backbone integrity and plug genders, and all the while builds a system database from which it can produce various valuable reports, and even a bill of materials"