NS100Fundamentals ofNaval Science

Precise Piloting

Objectives:1. Describe shiphandling characteristics.

2. Demonstrate how to calculate advance, transfer, and turn bearings.

3. Determine position in relation to track

4. Demonstrate how to calculate danger bearings.

Handling Characteristics Turning Circle - The path followed by the pivot point of a ship during a 360 degree (or more) turn using a constant rudder and speed.

- The pivot point for most warships is about 1/3 the way aft from the bow when the ship is going ahead. It is important to note that the bow turns inside the path of the turning circle, and the stern swings outside the turning circle.

60CDEUFGATHBPTypical Ships Turning Circle

Handling Characteristics Advance - The distance gained in the original direction the ship was traveling from the point that the rudder was put over to the point where the ship is steady on the new course.

- The maximum advance will be for a 90 degree turn.

End ofTurnStart ofTurnOriginal CourseAdvanceMeasured from the point the rudder was put over to the point where the ship is steady on its course

Handling Characteristics Transfer - The distance gained, perpendicular to the original course from the point where the rudder was thrown over, to the point where the ship is steady on the new course.

End ofTurnStart ofTurnOriginal CourseDistance measured perpendicular to the original course

Handling Characteristics Tactical Diameter - The transfer of a vessel during a 180 degree turn.

Final Diameter - The diameter of the approximate circular path that a ship describes if the rudder is kept over indefinitely.

EBAFDTactical DiameterCTactical DiameterFinal DiameterOriginalCourse000Wheel Over

Handling Characteristics Standard Tactical Diameter - A specified tactical diameter is laid down in tactical publications for naval ship types (i.e., frigates, destroyers, cruisers, and aircraft carriers).

- This data is used when ships are maneuvering in company to ensure all ships turn at the same rate, and the correct spacing between ships is maintained.

Handling Characteristics Standard Rudder - The amount of rudder required to ensure a warship achieves the ordered standard tactical diameter.

- This rudder amount will vary between warship classes.

EBAFDTactical DiameterCTactical DiameterFinal DiameterOriginalCourse000Wheel Over

Handling Characteristics Turn Bearings - In order to plot the position at which the ship must put the rudder over (to turn onto a planned track), the figures for advance and transfer must be calculated using interpolation, unless the specific speed and rudder combination is defined in the tables.

50A

ADVANCE AND TRANSFER TABLE

SPEEDRUDDER ADVANCE/TRANSFERANGLE45deg turn90deg turn YDS YDS

6KTSSTD.117/55135/85FULL 67/40 55/55

10KTSSTD. 80/45125/80FULL 45/30 75/50

13KTSSTD. 125/85150/100FULL 100/75 80/55

Handling Characteristics Turn Bearings - Should interpolation be necessary, the figure for transfer is used first to find the point where the ship will be steady on the new track.

- The figure for advance is then used to determine where the rudder must be put over in order to intercept the new track.

100 0 100 200 300TRScale in Yards

Advance and Transfer TableAngle of TurnAdvanceTransfer15 180 1830 230 3045 270 6060 310 110 75 330 170For a 50 degree turn: Advance = 283 yds Transfer = 77 yds

A100 0 100 200 300BTRScale in Yards77yds90

A100 0 100 200 300BTRTB 270Scale in YardsTurn PointSteadying Point

A100 0 100 200 300BTRTB 27090CDScale in Yards

Lt Ho WO

A070 005 Actual Track - 1Actual Track - 2Pick a turn bearing navaid close to the beam.

WO

A070 005 Actual Track - 1Actual Track - 2Pick a turn bearing navaid parallel to new course automatic adjustment to back on track

- Many means are provided to help keep a ship on track (i.e., specially constructed ranges, direction lights,etc.).

- However, should nothing be provided specifically designed for the purpose, it is often possible to select an object that the ship runs towards and use as a head bearing. By knowing what the object should bear, the determine which side of track the ship lies.

Establishing Position

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