Re: Steering Cable Tension Estimate (no book)
That's your emergency tiller. The tiller delam is minor. Just epoxy and clamps. That access port is the right one. You can open that with a large pair of pliers-stick the ends of the handles in and turn, use a large screwdriver between the handles if you need leverage. The cables look OK. As I said above, just check them for frayed strands. If there aren't any, don't need to change them.
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio