Rudders, helm orders, and steering quadrants have been covered and recovered many times and it many threads on this board. A few minutes searching will yield more details than most people care to know.
Rudders and tillers are the direct descendants of steering oars which extend aft from the stern of a vessel to provide directional control. Steering oars remained in common use on lifeboats until well after WW-II. They also gave rise to "starboard" as the name for the right-hand side of the ship looking forward. It was common on larger vessels to put the steering oar on the starboard side as this was most convenient for right handers. So, the right side of the vessel became the "stear board" side which ultimate turned into starboard (pronounce by sailors "stab-erd").
Steering oars are tiresome, especially on large vessels or during heavy weather. Some bright builder or sailor came up with the idea of attaching the blade of the steering oar directly to the sternpost using hinges and the rudder (originally "router") was born. The loom of the old oar became the rudder post, but there was still something missing -- a handle to rotate the rudder for steering. Routers already had small handles for the purpose which were enlarged to become the tiller. The whole mechanism was simple and relatively inexpensive to build and far more effective than steering oars. The rudder/tiller system also made it possible to control larger ships...and we all know "bigger is better."
Because the tiller and rudder are in line with one another, pushing the tiller to the left causes the rudder to swing to the right and vice versa. Thus a command to "port your helm" would result in a right turn. When the quartermaster actually operated the tiller, this was obvious to even the dolts among the crew. But, ships kept growing and tillers became unwieldy. So, starting in the mid 19th century there began a race to come up with steering gear which could be located out of the way below decks, reduce the workload on the quartermaster, and not cost the ship's profits for half its working life. This eventually led to the quadrant and steering engine of Titanic.
Wheels for steering appeared early in the machinery age. Today, thank's to those damned infernal internal combustion coupes we think that everything steers from the top of the wheel. Turn the top right and the car goes right. But, there's no cosmic law requiring this convention. Ships had been using tiller orders for a thousand years or more. Sailors weren't about to change. So, in a ship like Titanic the QM was taught to steer with the bottom of the wheel. Thus turning the wheel the the left was the logical response to a "port your helm" command. And, as in the days of steering oars, the ship's head fell to starboard in a right turn.
Historically speaking, it wasn't the sailors who were wrong. It was the grease monkeys with their sputtering horseless carriages who got things mixed up. But, that's water under the keel now. In fact, the world had so standardized on the convention of steering with the top of the wheel by WW-1 that young farmhands conscripted into navy duty found sailor jargon beyond confusing. By the mid-1930s it had become both the fashion and the law to issue helm orders as "right" or "left" as perceived looking forward. This change was accompanied by a U.S. regulation to put up black and white signs defining the left and right side. These signs were required in pilot houses and other steering stations. You don't see them anymore.
So ends today's lesson. We've only touched half the story, however. The other half is to put this into context with the way ships pivot during maneuvers. Once again, those damned cars get in the way of understanding. But, that rant is for later.
-- David G. Brown