60' yacht - all LED

I am converting over to LED on my cruiser... So I am wanting to use the rope on all the handrails, as well as the rub rail - and even an arial run from the bow up over the boat to the radar mast - then down to the stern. I want to control the lights with a PLC, and power them off of the onboard 12V power system. So here are the questions...   can i run them off the 12V onboard power???   Can i do an arial run? - or do they have to be run on a cable for structural integrity of the rope its self.   Now the rubrails should be okay< as long as they are rated 68 - correct???

yes you can run the 12v led strip lights from your battery but i always recommend you use a fuse somewhere close to the battery is case you get a short.

what kind of control are you looking to get? a PLC will only give you on/off control where a RGB controller can give you full color control (if you are interested in the RGB strips) http://www.instructables.com/id/LED-Deck-Lighting-in-color/ some pictures of the RGB strips installed under a deck railing
http://www.youtube.com/watch?v=seQzT6a75jA RGB strips in a boat

as far as supporting them i would zip tie them to a cable for support but for shorter runs you could hang them.

and yes as long as you use the IP-68 ones you should be fine