Fix HD added mass on member end (Close #992)

modules/hydrodyn/src/Morison.f90

@@ -2110,6 +2110,8 @@ SUBROUTINE Morison_Init( InitInp, u, p, x, xd, z, OtherState, y, m, Interval, In
             END IF
 
          END DO   !J = 1, InitInp%InpJoints(I)%NConnections
+
+         Vn = Vn*TwoPi/3.0_ReKi ! Semisphere volume is Vn = 2/3 pi \sum (r_MG^3 k)
 
          p%An_End(:,i) = An_drag 
          Amag_drag = Dot_Product(An_drag ,An_drag)
@@ -2127,7 +2129,7 @@ SUBROUTINE Morison_Init( InitInp, u, p, x, xd, z, OtherState, y, m, Interval, In
          ! Constant part of the external hydrodynamic added mass term
          if ( Vmag > 0.0 ) then
             v2D(:,1) = Vn        
-            p%AM_End(:,:,i) = (InitInp%Nodes(I)%JAxCa*InitInp%WtrDens/ Vmag)*matmul(transpose(v2D), v2D) 
+            p%AM_End(:,:,i) = (InitInp%Nodes(I)%JAxCa*InitInp%WtrDens/ Vmag)*matmul(v2D, transpose(v2D))
          end if
 
          ! Constant part of the external hydrodynamic dynamic pressure force