Terry,
Independently operated paddle-wheels and bow-thrusters have not been needed on a couple of models I've built. They had good steering and general handing characteristics but, of course, couldn't "spin on the spot". A photo of the Eccleshall tug (free plan in the June 2014 issue of Model Boats) is attached.
This was achieved by using a reasonable model size rudder as opposed to the somewhat "skinny" scale shapes. It also helps if a balanced rudder, with about 1/4-1/3 of the blade area ahead of the pivot axis, is used. Another tip, which I picked up from a very old magazine, is to, if possible, extend the rudder below the hull bottom. This places some of it in the faster flowing water away from the sluggish boundary layers flowing next to the hull.
Yes, not scale but then neither I suspect would a bow-thruster be . If the enlarged rudder offends the eye, just do what many have done and have a "scale" rudder for show which is replaced by a sailing rudder which is hard to see when the model is afloat.
Glynn Guest
