A ship's wheel or boat's wheel is device used aboard a water vessel to change that vessel's course. Together with the rest of the steering mechanism, it forms part of the helm. It is connected to a mechanical, electric servo, or hydraulic system which alters the vertical angle of the vessel's rudder relative to its hull. In some modern ships the wheel is replaced with a simple toggle that remotely controls an electro-mechanical or electro-hydraulic drive for the rudder, with a rudder position indicator presenting feedback to the helmsman.

Prior to the invention of the ship's wheel the helmsman relied on a tiller— a horizontal bar fitted directly to the top of the rudder post— or a whipstaff— a vertical stick acting on the arm of the ship's tiller.