NavList:

Magnetic compasses and corection of its errors are covered in Bowditch,1938, devoting 21 pages; 1977, devotes 56 pages; 1962, 54 pages.  Dutton, 1942, 46 pages; 1934, 13 pages; 1969, 45 pages.

The best coverage of corecting the compass is in Bowditch, 1962.

In the 1982-86 time frame I picked up some pocket money corecting sailboat compasses at Saugatuck Michigan where my girlfriend kept her Pearson Ariel.We'd spend weekends there in the summer and I brought along my trusty astrocompass. With this instrument it took no time to adjust sailboat compasses. I mounted the astrocompass on a board that I would put on the cabin roof snug against the hatchway tracks which very accurately paralleled the longitudanal axis of the boat. So a little computation and less than 30 minutes seadying on a series of  magnetic headings determined by use of the sun and the job was done. The time spent on the water and the usual beer and invitation to dinner garnered many friends for us.

gl