It will be fine. I have a 4ft Shakespere 4400 antenna on a small center console boat. The tip might be 7 feet off the water. No trouble talking to the USCG antenna 10 miles away or hearing boats calling bridges 6 miles away. I rountinely talk to a friend with one in Atlantic City NJ from my other boat in Cape May. Thats well over 30 miles. Some days are better than others.
With your additional antenna height, 10 miles or more should be no problem.
1984 Monk 36 Hull #46
Englewood, FL and Cape May, NJ