The "C" drive is in two assemblies:
- the upper unit (that is coupled to the engine transmission) weighs, I would estimate, about 80 pounds. Below the gearbox of this upper unit is what I recall Olivier calling the "trumpet" which has about a 3 inch wide sleeve of neoprene-like gasket material around it where it engages the hull structure sealing the flange around the vertical drive shaft hole. Around that is the hose clamped to both the hull flange and the trumpet.
- The upper unit is supported, then in three places: at both sides of the top by the steel cross members bolted to the engine angle iron stringers and by the trumpet resting on the hull with the gasket in between. None of its weight is carried by the keel.
- The lower unit weighs, I'd estimate, about 50 pounds and is supported by the keel at the bolt. As I recall there were two washers (shims) under the lower unit on the bolt, plus a rubber sleeve and steel compression sleeve around the bolt. The top is sealed with silicone after the bolt is secured..
- There is a lifting eye on the engine room overhead straight above the upper unit to facilitate removal and adjustment with a block and tackle. (Feel around inside the insulation.)
If your engineer replaced all the engine frame mounts I could see the possibility of the "C" drive being askew. If he just did the engine then it sounds like an issue with the engine-to-C drive coupling.
Good luck with it.
Craig SN68 Sangaris, Delray Beach, Fl