Gary,

the range is defined by the kit you use, the frequency its on and sometimes the aerial heights. As a GUESS I'd say that no ordinary basic radio control units [40MHz 27MHz 2.4GHz] will give more than 80 to 100 metres operational range. There is also a restriction on the power output permitted on these sets to, that will be under some of your legislation and here's a link to the website.

http://www.ukrcc.org This is the UK website for permitted frequencies and power is mentioned too, a maximum of 100mW.

I must say that at 100 metres (I have a lake much longer) I can just about infer which direction my yacht is pointing, left or right, but cannot really discern whether its coming or going from me unless I make a turn to bring the bow towards me. The yacht mast stands near 6 feet above the water and the sails are white. I cannot really see the white hull. That's using 2.4GHz and also 40MHz. I find that on 27MHz I can only achieve about 80 metres maximum.

Can you really see a bait boat at 100 metres, and the fish associated with that area of water? You'd require an on board camera (available) for that surely, and yes, the legislation also controls what frequencies may be used for telemetry as well.

Kimosubby

27MHz, with receiver aerial curled inside the superstructure, range around 150 yards. Same radio with the aerial vertical in a yacht, range 400 yards, but with the visibility problem as above. Range is vastly improved when it is remembered that the transmitter is a radio, not a rifle. The signal comes out sideways, not from the pointy end.

I've just been sailing a Joysway Explorer using the supplied 2.4GHz radio. 200yards plus, no problems other than guessing which way the boat was pointing when that far away. And guessing which way the wind was blowing where the boat was.

Since transmitted power is legally limited, but easily achieved, most hobby grade transmitters give out the full permitted power, and range becomes a matter of the receiver getting the best signal. Range is often apparently reduced due to local interference, usually from the motor(s), swamping the wanted signal, which gets fainter as range increases.

Watch out for "park flyer" radios. These are low power and not intended to have full range. OK for their intended use, but unfortunately attractive due to their relatively low cost.