Re: Steering Cable
Easiest way would be to remove the old one, lay it out on the ground and then measure it.
If the cable is missing, measure from the centre of the steering helm to the side of the boat, along the side of the boat from even with the helm back to the transom, and then from the side of the boat to the centre of the transom. Add the three together and then round up to the nearest foot - do NOT round down, and there's your cable length.
Or, read this page for more details:
http://www.iboats.com/basics/measure_steering_cables.html