Regarding the efficiency of the azimuthing drives... I own Anjumal, which was the last Cape Horn to be delivered. It was built with a mechanical azimuthing drive, also called a z-drive. The reasons for the mechanical choice over hydraulics were better fuel efficiency and less hydraulic whine. I have not been on a hydraulic drive boat while underway, so I cannot make a direct comparison. My boat is 65' long, beam of 20', and draft of 6.5', for 210,000 pounds loaded with fuel. I get about 8 knots at about 8 gallons per hour with the Cummins 440hp diesel running at about 1300 RPM with a clean bottom and calm water. This fuel usage has seemed comparable to figures others on the list have calculated for a boat with that displacement. If my results are a little worse than typical, then I would attribute it to the bilge keels and the beam. The bilge keels look like fixed stabilizers on the outer edge of the bilge. They reduce the rolling and allow the boat to sit upright if grounded, a feature I used this fall to careen the boat in order to paint he boot stripe, change out the zincs, and clean the bottom during a tide cycle. The bilge keels also offer a great deal of stabilization if the hydraulic stabilizers were to have a malfunction. The active stabilizers are positioned inside of the bilge keels so they are fully protected from any grounding possibility. Mike described a fixed hydraulic prop system on a Cape Horn 55 he delivered. This is very different than a z-drive. It is simply a hydraulically driven standard propeller coupled to a hydraulic pump on the main engine. It offers the flexibility that Phillip described for engine mounting and alternate powering, permits an optimum propeller angel to the boat, but does not have any steering function as the z-drive does. I have been told there is an efficiency penalty for hydraulic drive. There should not be an issue with hydraulic leakage that cannot be corrected. Although I am not hydraulically powered, I did find hydraulic fittings for the stabilizer/windlass/bow thruster system that needed a little tightening after the initial break-in period. All have been tight since. From my knowledge of the 65's (the Cape Horns that offered the Z-drive), the boats built with out the z-drive were one that had a v-drive due to initial cost considerations and the other with twin engines due to owner preference. The estimate of $100K to $150K premium for the z-drive is correct. I'm happy to share any other experience about the z-drive or Cape Horn that the list or individuals find interesting. -Wray