A helmsman or helm (sometimes driver) is a person who steers a ship, sailboat, submarine, other type of maritime vessel, or spacecraft. The rank and seniority of the helmsman may vary: on small vessels such as fishing vessels and yachts, the functions of the helmsman are combined with that of the skipper; on larger vessels, there is a separate officer of the watch who is responsible for the safe navigation of the ship and gives orders to the helmsman, who physically steers the ship in accordance with those orders. In the merchant navy, the person at the helm is usually an able seaman, particularly during ship arrivals, departures, and while maneuvering in restricted waters or other conditions requiring precise steering. An ordinary seaman is commonly restricted to steering in open waters. Moreover, military ships may have a seaman or quartermaster at the helm. A professional helmsman maintains a steady course, properly executes all rudder orders, and communicates to the officer on the bridge using navigational terms relating to ship's heading and steering. A helmsman relies upon visual references, a magnetic and gyrocompass, and a rudder angle indicator to steer a steady course. The mate or other officer on the bridge directs the helmsman aboard merchant or navy ships. Clear and exact communication between the helmsman and officer on the bridge is essential to safe navigation and ship handling. Consequently, a set of standard steering commands, responses by the helmsman, and acknowledgment by the conning officer are widely recognized in the maritime industry. The helmsman repeats any verbal commands to demonstrate that the command is heard and understood. The International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) requires that a helmsman be able to understand and respond to helm orders in English. The proliferation of autopilot systems and the increased computerization of operations on a ship's bridge lessen the need for helmsmen standing watch in open waters. Helm commands Helm orders or commands fall into two categories: rudder commands and heading commands. A rudder command dictates changing the angle of the rudder, which is a single-event action, whereas steering a heading is a comparatively long event and will require ongoing or continuous rudder adjustments. The following are helm orders used in the United States Navy and United States Coast Guard: Rudder Midships (Bring rudder angle to 0 degrees) Meet Her (Counter steer to stop the movement or