Re: C&C 30 mast step
Not really,although you may be able to get a sense of it. There is a narrow (8") floorboard in the C&C 30 immediately aft of the mast step. Lifting this gives you access to the aftmost frame supporting the mast step. If this is in bad shape, you can assume the others (I think there a 2 others) are also.
If it looks ok and is solid to probing with an awl, I might let it go until the next time the mast is pulled. The rest of the dismantling job is easy.
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio