Thanks for clearing that up for me. I had always thought they went full in either direction then to where they wanted because it was more like a reset. To prevent say someone bumping the handle a notch. But that makes more sense why they did/do it.During the Cameron’s movie allision scene, we see Murdoch activate the EOT (Engine Order Telegraph) handle from Full Ahead to Stop to Full Astern. In just that split second maneuver, there are two major goofs. First, the engines were never ordered Full Astern. If so, the firemen would have seen a white light in the boiler rooms meaning to be cautious as the engines were about to be maneuver but still needed steam pressure.
Second, Murdoch activates only the right handle of the standard EOT on the starboard side and soon after, the right handle of the emergency EOT off the navigation bridge center. It is quite evident that the stage director didn’t have a clue of how EOTs were working. Olympic Class had 3 propellers, two of which propelled by reciprocating reversible engines and a center one activated by a non-reversible steam turbine.
All engines were engine room controlled. The steam turbine was activated from Half Ahead upwards and most probably by bridge to engine room phone. As the reciprocating reversible engines were the ones used for maneuvering, they needed an order transmitting system (EOT) mechanically connected to the navigation bridge via very similar to bicycle chains and pulleys.
Apart from two docking & maneuvering order telegraphs, the bridge was outfitted with one standard EOT on the starboard side, one standard EOT on the port side and one emergency EOT off the navigation bridge center in case of standard EOTs malfunctions. Each EOT had two independent order setting handles thence 4 independant chains. The right handle ordered the starboard engine while the left handle the port engine. Therefore, to order both reciprocating engines to stop, the officer had to move «both» handles. Moving only one handle would order only one engine!
An EOT sounds a loud bell as soon as the handle is moved to another engine setting. But the engine room is a very noisy environment. To make sure that an order from the bridge is well heard by the engineers, if the bridge officer wants to go from say Dead Slow Ahead to Half Ahead, he will bell the ETO from Dead Slow Ahead to Stop to Half Ahead. That way, instead of hearing only 2 bells they will all hear 6 wake up bells, but the final result will be the same; an engine going to Half Ahead from Dead Slow Ahead.
Now just imagine the bell concerto followings a harbor pilot calls during maneuvering; Engines Half Ahead Both … Engines Dead Slow Ahead Both … Starboard Engine Stop … Starboard Engine Dead Slow Astern … Starboard Engine Half Astern … Port Engine Half Ahead … Port Engine Stop … Port Engine Half Astern … Starboard Engine Slow Astern … Stop Both Engines … in rapid succession !!!