DaleH
FOUNDER of Classic Parker Forum
Well, in reality there is no firm answer. Just remember this, antennas operate on line-of-sight from sending antenna to receiving antenna. So 'height' is your friend. I'd say offhand such a handheld would only be good for 4-5 miles in practical use.
Reference: http://www.boatantenna.com/faq.html
Reference: http://www.boatantenna.com/faq.html