A 100-tonne crawler crane is required to lift a load 6.5 m tall to a position 30 m above the surface on which the crane is operating. The load must also be placed 29 m away from the centre of rotation of the crane. The length and weight of the block, hook, and slings that are required to attach the hoist rope to the load are 7 m and 1800 kg respectively. Determine the minimum boom length when the boom length can be increased in increment of 3 m.