The USCG issues a Marine Safety Alert on this potential issue after numerous reports of degraded radio communication
Promotional Video from Fundamentals of Seamanship: Navigational Rules on Rule 22 which defines visibility of Navigational Lighting
I still think that many boaters don't realize the added safety, tracking, and navigation capabilities possible when GPS is integrated with portable VHF, though the Standard Horizon HX870 has been earning great reviews for a while.