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This illustration shows how the Imperial Japanese Navy used the measurement of the angle subtended by a ship to estimate the ship's angle on the bow. The target course was the most difficult piece of target data to obtain. In many cases, instead of measuring target course many systems measured a related quantity called angle on the bow. Angle ...
2 position bars for setting the initial and final stations; A speed bar, on which the speed of the ship (relative to the flagship) was set, and which was clamped at one end into the diameter grove by the speed ratio clamp; A guide bar; A circular disc; To use the instrument, the course of the flagship was first set on the guide bar.
Coincidence rangefinders work through the principle of triangulation. In the pictured example, triangulation can be used to determine the range of the ship 𝑑.The position of the lenses A and B are known, and the angle of the lenses α and/or β is set by the operator so that both are aimed at the target.
Aboard ship a dead reckoning plot is considered important in evaluating position information and planning the movement of the vessel. [8] Dead reckoning begins with a known position, or fix, which is then advanced, mathematically or directly on the chart, by means of recorded heading, speed, and time. Speed can be determined by many methods.
Decca position coordinates were directly displayed by four decometers and these were plotted on a conventional chart that had been over-printed with Decca lattices. The Decca Navigator System was a hyperbolic radio navigation system that allowed ships and aircraft to determine their position by using radio signals from a dedicated system of ...
The measurement of relative bearings of fixed landmarks and other navigational aids is useful for the navigator because this information can be used on the nautical chart together with simple geometrical techniques to aid in determining the vessel's position, speed, course, etc.
Plan position indicator (PPI) display showing polar display and radar sweep. A real radar display would show hard terrain features and look recognizably map-like, and from the sea, match well with land features of local nautical charts matching and sending strong clean radar echos back to the ship at sea.
When corrections are received all charts are corrected in the ship's folio and recorded in NP133A (Admiralty Chart Correction Log and Folio Index). This system ensures that all charts are corrected and up to date. In a deep-sea vessel with a folio of over three thousand charts this can be a laborious and time-consuming task for the navigator.