If that's an issue, get a teather and attach it to your harness, belt, beltloop, or whatever. If you want to attach one to a float, for example, the Icom M88 only weighs less than 10 ounces. http://www.icomamerica.com/en/products/marine/handhelds/m88/specifications.aspx

I've found that the bulk of the use is in a cockpit, bow, or dingy (since it's generally illegal to use it ashore ;^) ) The issue I've found is the batteries tend to wear down too quickly -- or that you didn't charge the unit since the last intermittant use.

If you're in a lifeboat, your distance of speaking isn't too great -- in the water it's worse (except to an aircraft that's listening); however, if you are in either, I'd rather have more talking and listening time.