A vessel is transiting a channel and the navigator takes successive bearings on a single lighthouse. The relative bearing at the first observation is 045° relative and at the second observation is 090° relative. What technique has been applied, and what distance information does it yield?

1. A. A danger bearing; it indicates the vessel is inside a safe arc
2. ✓ Doubling-the-angle on the bow; the distance run between the two bearings equals the distance to the lighthouse at the time of the second bearingCorrect
3. C. A running fix by advancing the first LOP; the distance to the lighthouse equals half the distance run
4. D. CBDR analysis; the constant bearing indicates risk of collision with the lighthouse