Hello I am new here - I live aboard my 37’ sailboat and am interested in installing a POE network on my boat using a POE switch that is hardwired into the 12v house bank. The switch steps up 12v to 48v and then has several POE outlets each with a 30 watt power budget. IP security camera, lights, sensors, raspberry pi, monitors, NMEA backbone, there are many devices that could be connected to this system.
The big disadvantage is the losses you’ll incur by converting 12v to 48v. Depending on the amount of devices you use that are PoE, it may be better to look at specific devices that could run off of 12v instead of PoE. In particular, things like lights, sensors, and raspberry pi would likely be better to run either natively off of 12v, or with specific converters that might be more efficient.
You’re probably going to find that a lot (most?) PoE devices are not expecting to operate on a low power basis. They’ll blow through 30w per port like nothing, unless you start digging and find ones that ARE designed for low-power use. Bearing in mind that most RV setups are expecting there’s a ready source of wattage in the form of a generator, engine or hefty battery setups.
Start with a plan, not with devices. You don’t want to find yourself painted into a corner with gear you’ve got on-hand that really might not be ideal for the intended solution.
Then there’s the problem of connector form-factor. The RJ45 connector is not ideal for marine environments. The contact surfaces are small and the connector itself isn’t sealed against moisture. You can, of course, get various bulkhead and other style connector shrouds that attempt to solve this. But then you’re into added expense and much larger connector footprint.
Don’t try to solve everything with just one platform. Things like NMEA-2000 exist and can do a pretty decent job of handling most of the things you need for boating. Not cameras or video monitors, of course, but quite a lot of other things.
There’s a tendency to want to find an all-in-one solution, I’ve been there myself. I don’t think it exists. And the ones that “sort of” come close often end up being a burden to use when you need actual boating navigation. Too many fiddly parts that end up getting in the way of being useful. Updates for this, conflicts with that, abandoned software/hardware… the list goes on.
Not that dedicated devices haven’t had their share of problems, but they continue to perform their functions for which they were purchased.