R/C Naval Combat

Being from the Mine Warfare world I can tell you that differential steering is a way of life for smaller ships to aid in maneuvering. Part of that is the fact that we had Controllable Pitch Propellers (CPP's) and could reverse thrust without reversing the rotation of the shafts. Larger ships do use differential steering, HOWEVER it is used almost exclusively in port for tight quarters maneuvering with the aid of tugs. To reverse thrust on a shaft on a large vessel without CPP's (meaning reverse rotation). You typically must:

-Reduce all power to shafts, lower ships speed
-Kill the ahead bell on that shaft
-Allow the shaft to slow down to an "idle" speed, also known as "freewheeling"
-Apply the brake to that shaft to stop all revolutions
-Engage the shaft locking mechanism
-Engage the reversing gear attached to the MRG (Main Reduction Gear)
-Disengage the locking mechanism
-Release the braking mechanism
-Bring shaft RPMs back up

Again, this is to the best of my knowledge. However seeing as I have been underway on minesweepers (american and british), submarines, and large surface vessels (DDG and a supply ship) I imagine it is reasonably accurate. This is virtually the same procedure on all those vessels. A much more realistic representation in the hobby is to allow power to be cut to a shaft but no reverse thrust applied. Being as ships couold cut power to any shaft then you should be able to as well, and in whatever manner benefits turning the best.

Das Butts

Posted By Tugboat on 02 Dec 2011 05:55 AM
Nope, all that momentum in the driveline being quickly reversed would produce a current spike likely to fry things. Honestly, at battle speeds, I don't see the WW2 and older battlewagons reversing one side and speeding up the other. Unlinking the throttles and operating one set of engines locally (the main control stations don't typically have the means to control each side of the steam plant individually) was a non-trivial thing and one that would not likely be done in combat. If it came to a vote, I would vote no on combat reverse and differential steering because neither would have been realistically used in our time period. SMS Seydlitz steaming home from Jutland in reverse wasn't a combat reverse

Another issue with differential steering is that if you hook up an ESC to each drive motor, you could freely have one side all ahead flank and the other all back full, which as Herr Butts pointed out is unlikely to happen in a big steam plant.

That is what I would have thought, the vague memory was that it was to prevent a collision during manuevers pre-war.  It was certainly not S.O.P.