No, I do not need a Rolaids but thanks for asking
Just bought a 1990 C&C 34+. When motoring at lower rpms, say about 1000-2000, there is this kinda irregular thumping sound which I can feel in my feet and hear. It is not loud and not shaking the boat but still a concern. Just had the boat out for survey and the shaft etc. "looked all right." Boat has a dripless seal which all seems to be in order. Motor mounts seem OK, not a buuch of movement. The sound does seem to be moderated by rpms though. Also, it has started to make a chirping sound, also effected by rpms. At first I thought this could be the fan belt or water pump/alternator but those seem OK.
Could the shaft seal make such noises and vibration? Ideas?