照咁睇打蛋器都可以做船

cmpang

this type of propeller works on  variable pitch.each individual blade's pitch angle varies according to its dynamic position  in relation to the boats axis. due to its symetrical geometry, it can push the boat in any 360 degree direction as desired. operation similiar to the rotor head of a helicopter and is most useful in the modern tug boats in an over crowded harbour. Some fire boats also uses this type of propulsion for its superb manouverability. On spot rotation and moving sideways are some of its major advantage over conventional driving mechanism.
方舟 has made a Los Angeles class fire boat using a Voilt system from Robbe.

no 船王 should miss this one from his fleet collection.. 吾知我地既老，中，青船王們點睇?

cmpang

The basic principal is complicated but the real world control is easy. You control each of the two servo pairs by the two control sticks on your transmitter. Each gimble determines the X/Y corlordinate direction of the trust flow as desired while a fifth control knob control the total power output from the propulsion system. As  easy as playing a computer game...

e.g. pushing both sticks up will move the boat forward, right stick up to turn left, right up and left down is rotating anticlockwise... sounds familiar enough ？ What makes it different to our tank control is it can shift the boat sideways by pointing the left/right gimble to the left/right direction ...