Marine current farm (MCF) equipped with squirrel cage induction generators (SCIGs) influences on the voltage stability of the power network. Thevenin-based voltage instability risk indicator is a simple and local index that can be used for voltage instability prediction from a load or zero injection bus. This indicator is modified to evaluate the voltage stability from MCF bus. In addition, a Thevenin-power flow tracing-based load shedding approach is also presented for preventing voltage instability. The method compares two equivalent Thevenin impedances of the main network and MCF for total active and reactive power calculations. Then, the total values are used for load sharing and load shedding by power flow tracing algorithm. The proposed hybrid method is tested on IEEE 14-bus test system considering different contingencies. The results confirm the capability of the proposed indicator and load shedding approach in timely prediction and proper prevention of voltage instability problems, respectively.