I replied directly to Jeff regarding my as yet limited, but very positive experience with The Evolution Marine Shaft System(EMSS). It is installed on our nearly completed 38' Downeast Sedan Cruiser. A semi-displacement hull, with lines from a traditional lobster workboat, engine is single Cummins 450hp with special (softer) mounts. As ex-sailor of many years, the issue of noise and vibration was a primary concern, and I was determined to have the most quiet version of a semi-displacement hull, driven by a single large diesel capable of extended cruising. Particular attention was given the engine intake/exhaust system, comprehensive sound insulation and the EMSS was specified. Sea trials, still underway, indicate very little vibration, actually none, at cruise 15-16knts and top speed 23knts. Sole, engine room bulkheads and hull interior over prop are insulated with Soundown products, resulting in surprisingly quiet ride. Mfg website: <A HREF="http://www.evolutionmarine.com/">The Evolution Company Inc. - Home of The Evolution Marine Shaft System</A> The boat can be viewed at builder's web site: <A HREF="http://www.snugharborboatworks.com/index.htm">Snug Harbor Boatworks, Duxbury, MA</A> Click on "Shearwater 38" and "Under Construction", there are 3 PICS under the 10/01 sea trial listing. Regards, Gene Ali Duxbury, MA