Timing a lighted aid requires a timing device that will give elapsed time. Many wrist watches have this capability but experience has determined that a sports watch (inexpensive, available at K­Mart, Wal­Mart, Radio Shack, etc.) is an easier device to use because of the large buttons and easy-to-read display. And, because it is easier to use, it will tend to give more accurate results. However, the less expensive devices don't have an illuminated display so a flashlight with red lens (to protect night vision) would be needed.

Each Aid Verifier will develop their own techniques for doing the actual timing of flashing lights. The following is suggested as a "starting point" technique for someone who is new to aid verification.

• Always start and stop timing at the end of the last flash in the period. This eliminates the "anticipation" factor which is created when timing repeated sequences.
• Some people are in the habit of counting "one" on the stroke when they start the watch. Of course this throws off the count of the number of flashes. To break this habit, count "zero" when you push the start button on the stop watch.
• Timing lighted aids is performed at night. The person doing the timing should be dedicated to that task and should not be interrupted nor should they be expected to be manning any watch positions. Positions should be rotated during the mission.

The following diagrams represent the statements made above:

Note: The following applies to all lights -- on Coast Guard aids, on private aids and on bridges.

In order for a light to be visible as expected, the light must be level so as to show within the viewing range of the mariner. One question on the Coast Guard and private aid verification worksheets asks "Tower Listing Over 15 degrees?" This question is really asking "Is the light in focus and / or are any dayboards leaning more than 15 degrees?"

Sometimes it has been observed that the structure (pilings, cells, concrete piers, etc.) is listing as much as 35 to 45 degrees. Often these structures cannot be repaired without totally rebuilding the aid. However, the tower mountings and leveling plate for the light assembly do allow the horizontal position of the aid to be adjusted so as to be in focus (e.g., within the +/- 15 degree tolerance). In this case, as long as the aid can be seen within the viewing range of the mariner, it would be considered as "Watching Properly" assuming that all the other characteristics were operationally correct.

If the aid (light, dayboard, etc.) is not in focus, then specifics regarding the problem should be noted. The structure may show signs of damage. Problems with bridge lighting have been observed because the light fixture was installed facing the wrong direction.

Flashing lights are considered to be "Watching Properly" when the actual (timed) number of seconds for the expected number of flashes falls within plus or minus three seconds (57.0 to 63.0 seconds inclusive). Example:

If a light with published characteristics of Fl (2) R 6s actually showed twenty flashes in 58.4 seconds, the light would be considered as "Watching Properly" AS FAR AS THE TIMING CHARACTERISTICS ARE CONCERNED.

Referring to the example above, the Aid Verifier should enter the timing results on the aid verification worksheet as:

"20 flashes in 58.4 seconds"

Many private aid facilities have more than one light. Unless ALL lights are "Extinguished", the Aid Verifier must identify the specific light for each of the timing results. The table below shows some conventional ways of doing this. It may also be easier to habitually always list the lights starting with most upstream light.