Peerapat was operating the Starboard Offshore crane and preparing to lift the work basket from main deck so that crew could perform cleaning of the exhaust vent located there. From his elevated position, he observed a colleague (SSE) standing on the top rung of a stepladder performing maintenance on the port leg. This position put the worker in an unstable position where he could fall. Peerapat haulted the lift he was conducting and immediately called the Paint Foreman using the VHF radio, to go and perform a TOFS with the worker and explain the danger that he was placing himself in.