Re: Adding 12v receptacle
Weatherproof receptacles are the way to go, but you might also try to mount it in a somewhat sheltered location so it doesn't get rained on much while being used since your phone/GPS cord is probably not outdoor rated.
When I outfitted dad's boat with a receptical at the helm, I mounted it just under the console to keep rain off of it. It is still visible and accessable, but also somewhat protected. It is on a dedicated 10 amp circuit for running spotlights, but we find it is mostly useful for the purposes you are suggesting.
You don't have to protect them though - I just like to when possible.
Mount it where it is most convenient for you to access. Depending on your specific receptical, it may be possible to disassemble it and pass it thru a hole you drill in the dash. Reassembled it will hold itself in place and be flush (mostly) with the dash facing.
Just make sure you install a fuse in the wiring or either feed it directly from the fuse block or from a fused power source that won't cut anything critical (like the bilge pump or nav lights) if you find yourself in a situation where you are shorting/overloading and are popping fuses. If you run out of fuses and lose your stereo it is just an annoyance. If you lose your nav lights at night it is another situation entirely.
You can get these things at all kinds of places, but buy something that you feel is of good quality.
Best of luck.
Steve
