Gums , if you don't mind thread drift , not INS gyro drift ...
My ancesters were beach launching fisher folk on the North Norfolk coast . They reckoned that a compass worked really well whilst you were in sight of land ...Out of sight , it was useless.
By observation on a few years of Pond crossing . Westbound if setting initial course correctly from a VOR or waypoint ..to keep nearish to nav. flt plan ..just turn Left about 5 degrees every hour . Landfall won't be a million nm out .
Eastbound , no idea .. it was normally dark .
Please keep the tales coming , I'm learning a lot . But some is going straight overhead .
rgds condor .