Check My Plotting...
Well, if I did it right, you''re close. Your Variation is 7 deg 30 min W (I think, you didn''t say 30 min, but I am assuming that is what it is) with an annual increase of 10 min. In 4 years that is 40 min, so your total variation is 7 deg 30 min plus 40 min (you dropped the 30 min from the original year 2000 variation), which is 8 deg 10 min W. So, your magnetic course then becomes 130 deg plus 8deg 10 min which equals 138 deg 10 min or in decimal form 138.17 degrees. Now correct for your deviation as you did and you get a compass course of 134 deg 10 min.
However, as the other replies indicate, you won''t be able to steer that accurately, so you''ll just have to average it out over time. Your actual course will probably wander 5 or more degrees either side.
Gerhard
