Trim tabs

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Trim tabs are used on boats to help start in a downward angle to maximize lift at slow speeds. As the boat accelerates, the water pushes up on the trim plates providing lift to the stern which minimizes bow rise, and allows the boat to plane quickly.The rudder can also be trimmed with the rudder trim. In situations where constant rudder input is needed the pilot can move the tab on the rudder to compensate for pilot pressure. Therefore, in a long ascent which requires constant right rudder pressure, the pilot no longer has to maintain the rudder input manually. http://www.trim--tab.com

Trim tabs are used in aircraft to relieve pressure on the stick or yoke thereby decreasing pilot workload. The most common example of a trim tab is the elevator trim found in almost all aircraft. In a constant climb, or descent, the elevator trim tab is adjusted to maintain the angle of attack without pilot interaction. Relieving this force allows the pilot to focus on other tasks such as traffic avoidance.

Also, the ailerons can be trimmed. Rudder trim is less common, and aileron trim is found mostly on large fixed-wing aircraft (two engine and larger with a notable exception being the single engine DHC-2 Beaver).

Not only does keeping an aircraft trimmed properly reduce pilot workload,it also increases fuel efficiency by reducing drag. For example, if an aircraft is climbing it will have a tendency to yaw which increases parasite drag because the craft is not flying straight into the flight path but at a slight angle which puts more of the fuselage into the wind.