STEP 1
Determine the Ho and LHA of Aries.
STEP 2
The Polaris Tables are entered to find the three parts of the Polaris correction. I use the sample problem at the bottom of the table on page 275 to provide the format and I add this to my sight form. The entering argument for the tables is the LHA of Aries.
STEP 3
To find the ao part, the table containing corrections for each integral degree of LHA is used with interpolation, if necessary, to arrive at the ao correction corresponding to LHA of Aries
STEP 4
Now we proceed to the middle table, in the same column, to obtain the a1 part. The entering argument in the left margin is the tabulated latitude closest to your DR latitude.
STEP 5
The a2 part is obtained from the lower third of the table, staying in the same column, opposite the month of observation. As a final step in finding the total correction to be applied to Ho, ao ,a1, and a2 are always added and the required - 1° is a constant.
STEP 6
Staying in the last column, enter the Azimuth part of the table with your DR latitude and extract the true azimuth of Polaris. Then find the gyro error and deviation. I have a form that I use, which I will publish on my blog with actual
Coast Guard exam questions.
