Diesel - Hydraulic - ultimate reliability
Two John Deere 6068 130HP each are driving hydro static hydraulic pumps (used in airplanes) to feed a hydraulic motor of 190 HP @ 550 rpm to turn a "big wheel" of a 38" bronze propeller with a pitch of 28. At cruising speed of 7 to 7.5 knots the propeller turns just about 450 rpm and the two John Deers run only 1200 rpm - properly torqued
Turn one engine off and run the other one with 2400 rpm and there is no difference in performance!
You can run on one engine only or on two, as you feel comfortable.
At cruising speed (7.5 knots) Eden Bound logged an average consumption of 1.3 NM per US gallon giving her a range of > 5,000 NM. Reducing the cruise speed increases the range dramatically.
Five fuel tanks can carry 4100 US gallons of Diesel (450 swim platform +1,000 mid stab +1,000 mid mid +1,000 mid port +650 forward). The 5 tanks serve (when not entirely full) also as trim tanks. Fuel transfers between the tanks can be remote controlled. The fuel transfer between the main tank(s) and the suction tank (6 USgal) in the engine room is fully automatic and redundant (fail safe system)
Each diesel engine has its own external diesel priming pump to easily bled the fuel system after fuel filter changes or any other service work done on the fuel system.
To safeguard the hydraulic propulsion system a leakage can be easily refilled out of a large hydraulic fluid tank (about 200 USgal) at the bow by transfer pump system.
For service work the hydraulic system (propulsion or auxiliary) can be drained into the main tank.
Oil change easy: there is a 60 US gallon lube oil tank; both engines and generators are connected to a pump out / pump in valve system and it takes less than 10 minutes to change the 20 liters lube oil of a John Deere engine. Means it can be done even while underway (run on one engine only for the 10 minutes)
Launch the down wind sail on long passages! There is a 55 sqm sail from ISTEC, Hamburg / Germany. Turn one engine off to save fuel or both and enjoy sailing.
Both engines are well maintained (lube oil & filter changed every 200 h) and have currently about 9,600 engine hours. Both engines are mounted above the waterline so that they can use a wet exhaust system of custom made epoxy mufflers and water lift.