Enter the distance between the centerlines of two legs that are opposite to one another. If there are an odd number of legs (therefore no two are opposite), then enter the diameter of a circle drawn through the centerlines of the legs.
If this field is left blank then program will add half the leg section length to the vessel outer diameter.
This input is only used to compute the forces and moments at the vessel-leg junction, which are needed for performing local stress analysis (WRC-107).