J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Flexible shaft couplings

It helped a little, but not much. A straight shaft, good engine mounts (one where the rubber isolators haven't degraded over the life of the boat) and precision alignment are more effective.

Welcome to the world of a 2 cylinder diesel engine. The 3YM30 on my J/109 is much smoother at all rpms.