  The H$\alpha$ velocity fields of a sample of six luminous blue compact
galaxies (BCGs) and two companions have been obtained by observations with a
scanning Fabry-Perot interferometer. The Fabry-Perot images, velocity fields
and rotations curves have been presented in a previous paper (Paper I). In
general, the velocity fields are irregular and often contain secondary
dynamical components, but display overall rotation. The two companions have
more regular velocity fields and rotation curves. In this article we analyse
the velocity fields and dynamics together with the morphology of the studied
BCGs, and present detailed mass models. In addition, we model the stellar mass
content by means of multicolour surface photometry and spectral evolutionary
synthesis analysis. By comparison of the masses of stars and those derived from
the rotation curve, we show that about half of the galaxies cannot be supported
by rotation alone. The morphology and dynamics of the BCGs suggest that the
starburst activity in these galaxies are most likely triggered by mergers
involving gas-rich dwarf galaxies and/or massive gas clouds.
