running fix technique Practice Questions

1. A running fix is necessary when:

• A.Only one charted object is visible and two bearings must be taken at different times✓
• B.The vessel is traveling at high speed and all bearings are taken simultaneously
• C.Three objects are visible but only two bearings can be measured accurately
• D.GPS fails and the vessel must use only depth soundings

Why: A running fix is used when only one charted object is available; the navigator takes an initial bearing, then a second bearing after a known run, and advances the first LOP along the course line by the distance traveled to obtain an intersection.

2. To obtain a running fix, a navigator takes a bearing on a lighthouse at 0800 and a second bearing on the same lighthouse at 0830. The vessel has been steaming at 12 knots on course 090°T. How far is the first LOP advanced when plotting the running fix?

• A.6.0 nautical miles✓
• B.12.0 nautical miles
• C.3.0 nautical miles
• D.9.0 nautical miles

Why: Distance = speed × time = 12 knots × 0.5 hours = 6.0 nautical miles; the first LOP is advanced 6 miles in the direction of travel (090°T) to intersect the second LOP at the time of the second bearing.

3. When advancing a line of position for a running fix, the LOP is moved in which direction and by what amount?

• A.In the direction of the vessel's true course, a distance equal to the distance run✓
• B.Perpendicular to the bearing line, by the distance run
• C.In the reciprocal of the vessel's course, by twice the distance run
• D.In the direction of the current set, by the leeway distance

Why: To advance an LOP, every point on the line is moved in the direction of the vessel's true course by the distance traveled (speed × elapsed time), and a new parallel line is drawn through those advanced positions.

4. A navigator shoots a 045°T bearing on a lighthouse at 1000. At 1100, with the vessel having run 10 miles on course 270°T, a second bearing of 090°T is taken on the same lighthouse. To find the running fix, the navigator advances the 1000 LOP:

• A.10 miles in the direction 270°T✓
• B.10 miles in the direction 090°T
• C.10 miles perpendicular to the 045°T LOP
• D.5 miles in the direction 270°T because LOPs are averaged

Why: The first LOP is advanced by the distance run (10 miles) in the direction of the vessel's true course (270°T); the advanced LOP is then intersected with the 1100 bearing to establish the running fix.

5. The 'doubling the angle on the bow' method is used to determine the distance to an object. If the first bearing puts an object at 30° on the bow and the second bearing puts the same object at 60° on the bow, then at the second bearing:

• A.The distance to the object equals the distance run between bearings✓
• B.The distance to the object equals twice the distance run between bearings
• C.The distance to the object equals half the distance run between bearings
• D.The distance to the object cannot be determined without a third bearing

Why: When the angle on the bow doubles (e.g., 30° to 60°), the vessel has formed an isosceles triangle where the two sides from the object are equal; therefore, the distance to the object at the second bearing equals the distance run between the two bearings.