Bruce asked " but I'd like to hard wire in a mount on the roof and then pop the antenna onto it when needed. "
Have a look at http://www.panorama.co.uk. They do a 'through roof' modular base called the M8 onto which you can attach whatever aerial rod you wish. The rods fix on using an allen screw to secure then to the base. I have that set up for Jannocks in-boat Nokia phone kit. You need to seriously think about a through roof earthed antenna, they may give much better service but if your battery isolation switch is in the negative battery feed (as Jannock's is) then when you turn off the switch the whole boat's negative return path could be routed through the radio coax. Luckily the Nokia car kit has negative feed isolated from the antenna and I have fitted a 'braid breaker' into the domestic radio aerial to prevent this happening. Graham www.jannock.org.uk
