Martin Underwood wrote:

- because a rudder at the front simply wouldn't work properly to steer the
boat?

It should work okay, or reversing wouldn't work on boats with rudders.

- because a rudder at the back gives greater manoeuvrability, in the same
way that dumper trucks on building sites have rear-wheel steering whereas
cars and lorries have front-wheel steering?

I think it's possibly a matter of general utility. On a dumper truck or
a fork-lift you don't want the steering to interfere with the mechansim
of the skip or lifter. On a boat you don't want your steering mechanism
to be the first thing to collide with obstacles you may encounter...

Pete.
--
Peter Clinch University of Dundee
Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/