Hello Angus,
With reference to my little exercise. Marty (mvsmith) saw this done in a narrow river when he was on a research vessel.
bows pointing upriver / to complete a full 1800 turn and sail off down river.
Luckely for me, the springline effect could be executed in favor of this exercise with the Northern Star.
Sometimes "the ship" (like the Vermaas) will not move at all, when a line is attached.
Adding to the presented example is the consideration where Marty is also refering to: the river
![Grin ;D](http://forum.shipsim.com/Smileys/default/grin.gif)
It would be great to have a ShipSim version with effects like wind, wave and currents.
Spending a lot of my sailing times on rivers, there is a variaty of ways to use moring- or tow-lines to direct the ship without using of propulsion or thrusters.
The currents against the side of (loaded ships) and the rudders of course, can therefor be used to stear (within limmits) the ship.
vr. gr. / kind regards, Erik