Or, you could opt for the 2.4 GZ radio, and never worry about the antenna again, as they're less than two inches long. The plus side, is that'll you'll never have to worry about changing chrystals, or having another radio take over control of your boat. Also, motor EMI causing control glitches is a thing of the past. Using the same radio for different models is also easy, just by selecting a preset program for each model.
I know someone will take offense to my next statement, but anything other than the 2.4's are obsolete.