Originally Posted by sunchaser
So would anyone care to raise the ante and comment on your after market installed hydraulic thruster system?
I think this might be a mute point since the OP already decided to go electric, but I would only retrofit hydraulics onto a 41' boat if I planned multiple hydraulic devices. If you intend to add active stabilizers then hydraulics are mandatory. Once you opt for hydraulics then a hydraulic windlass and/or hydraulic winches make sense. One of my pet projects has been to drive a high output alternator with a hydraulic motor because the hydraulic motor can operate at a constant speed over a wide range of engine speeds and higher speed improves cooling and efficiency.
Hydraulic systems can get quite complex, so unless you are a mechanical engineer, you may need some help engineering the system. The power source could also be problematic. Some main engines and/or generators can drive a power take-off which can be used to drive a hydraulic pump. The best pumps are variable displacement pumps, so you can vary the hydraulic power output to meet demand over the engines operating speed range. However, variable displacement pumps are very expensive. Some systems use a constant displacement pump with an electric clutch. This is OK for infrequent use devices such as a bow thruster, winch and windlass, but the on/off operation isn't good on a continual basis like for stabilizers. The most common power source is an electric motor driving the hydraulic pump. In the high power range, AC motors are cheaper than large DC motors, but if you go AC you have to run the generator to have hydraulics.