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→Mechanical V-Drive
With a V-drive, there is no reason not to have the engine room fully aft, taking full advantage of the forward hull for accommodation.
== Non-Mechanical Drives ==
=== Hydraulic Z-Drive ===
A hydraulic Z-drive such as the Thrustmaster [37] or Olympic [38] is the next step up from a V-drive. In this layout, the engine drives a hydraulic pump. This connects to a hydraulic shaft motor via hydraulic lines. The shaft motor turns the propeller shaft. Typically, the shaft and propeller are mounted so that the propeller can swivel through 360 degrees.
Thus, a Z-drive removes the need for stern thrusters. The engine does not have to be inline, and can be put anywhere convenient. Z-drives allow the engine room to be aft.
There is a bias against hydraulic drives because of their additional complexity, and perceived lack of efficiency and robustness. Hydraulic systems lose energy mainly through torque losses, and are typically 80-85% efficient. This is not quite as efficient as a straight mechanical or an electrical drive. If you have doubts about robustness, go watch some heavy equipment in operation. Z-drives of 4,000-hp and up are routinely fitted to tugs. The only thing against hydraulic drives is their cost.
== References ==
