The simple answer is no, but it might be different for various
groups.
Sea Scouting is a division of the Boy Scouts of America. If
someone joins Sea Scouting, then they have become a Venturer. It is
not necessary to have experience in Boy Scouts or had to have been
a Boy Scout to join Venturing and become part of a Sea Scouting
Ship. All Venturing programs are open to both male and female
members.