Are there only men sailing on the Viking longships?

No, Viking longships were not exclusively crewed by men. While men predominantly made up the crews for raiding and trading expeditions, archaeological evidence suggests that women also participated in maritime activities, including sailing and possibly even commanding ships. Viking society allowed for a degree of gender fluidity in roles, and women could hold significant power, especially in the context of family and community. Thus, it is likely that women were involved in various capacities related to longship voyages.