A high speed cable hoist system for conventional dockside container handling cranes of the type comprising a frame and a movable boom extending laterally therefrom. The high speed cable hoist includes a hoist cable speed enhancing system which comprises a frame having a stationary sheave set positioned at the bottom thereof and a vertically movable sheave head positioned above the stationary sheave set and adapted for vertical movement within the frame. Each of a plurality of hoist cables from the conventional hoist drums extend between and wrap around two or more sheaves in each of the sheave set and sheave head, respectively, and terminate. The sheave head may be selectively actuated by suitable actuating means in order that the speed of extension or retraction of the plurality of cables by the hoist drum may be increased by motivating the sheave head either toward or away, respectively, from the stationary sheave set.