Tunnel-Thruster Tragedy
Many ships are equipped with bow thrusters or stern thrusters. Today these consist of a propeller in a tube (tunnel) operating laterally.
The problem is: At higher ship speeds the Ventury effect reduces the pressure in the tunnel:
The propeller then runs in a vacuum and produces very little thrust.
The experience with those thrusters is that they loose their performance already at around 2kt and have no useable effect above 4kt.
That means they are of no use at most of a ships speed range, and even of no use in areas with high tide flows or river flow speeds.
Even more important is: They are of no use in case of an emergency!
No really good design!
The proposed paddle wheel thrusters are not affected by a Ventury effect and promise to work at all speeds.