RE: 40MHz or 2.4GHz?
illegal to use 35mhz for boats, its usually 27, 40 and 75mhz
i use 2.4ghz in my boats as theres no crystals involved, turn up, set up and boat around
if you have any CF inside the hull, the antenna will need to be outside the hull as the CF will cause interference, but 2.4ghz all the way