The mast extrusion for a C30 std rig is 40' and for a tall rig is 42'. The "I" measurement is one foot more (supposedly to the intersection of the cabin/deck). I would add another 4 feet for the topsides - to the water line. The masthead crane is 6" and the (old) anchor light is another 8". You will have to add on whatever wind instruments or antennae you have.
