In this paper transmission properties of PLC (PowerLineCommunications) channels in ships are discussed. A multi-port channel model is set up based on an equivalent lumped circuit that represents the transmission line characteristic of a power cable starting from the analytical solution of the telegraph equations. Then a Y matrix has been employed to compute the transfer function between power network ports, taking into account load variations. The effect of cables length and loads varying on transfer functions is investigated. The simulation results show that both the multiple branches and the cable length contribute to reduce the time-variant effect of the load on transmission performance. Therefore, the power line channel in ships can be considered deterministic.