Leah,
Marine components were used in earlier production Beavers because they were the most durable and moisture proof components that were available at the time. In the 80s and early 90s, Beavers even used expensive twist lock marine power cords that had to be unplugged from the coach and rolled up for storage every time that you moved locations. However, as the RV industry has matured, components have been developed especially for RVs, so the number of components in RVs that were designed especially for marine applications has diminished.
Gerald