yes, and the height of your antenna (and type of antenna) will greatly affect your range.
Just getting the antenna up 6 or 8 feet more will make a difference. So if you have a small boat, get the antenna as high as possible. They even sell antenna extensions to help with the height. Some people don't like the extensions as they may mean you need to lower the antenna when going under a bridge, etc. but if you want better radio range, the higher the antenna, the longer distance you will be able to communicate.
Some antennas have more 'gain' than others. The higher the gain 'gain' basically means that the antenna focuses the energy more than one with a lower gain. Higher gain antennas tend to focus the radio energy to the horizon (and works both for receiving and well as transmitting), but on a boat, the higher the gain, the more fading you can get as the boat rocks. This may be more of a problem on the ocean with swells and such, but just keep it in mind. A high gain antenna may be bad for a sailboat as it heels over a lot, but not so bad for a power boat as they tend not to spend much time on their side.
This page at Westmarine has a pretty good description along with good illustrations to demonstrate what is going on. It also has a good table that illustrates how much height can affect your radio range:
http://www.westmarine.com/WestAdviso...-a-VHF-Antenna