NavList:

Adding a bit more background:  compass dials are balanced at the factory for a particular location (magnetic latitude) using a small weight on the dial.  (If not, then the magnets would align with the earth's field.  At Hamilton the "dip" angle is greater than 70 deg; ie, that's right, the card would would be tipped 70 deg. ) That's all good until you change latitude (magnetic); the card follows along until it binds up.  (that's why when you go to the Southern hemisphere you need a compass balanced for the southern zones, but I digress.)

Wood vessels, FG vessels, AL vessels: all good; non magnetic.  But, as soon as you go aboard a steel (iron) vessel the card magnets are drawn (sometimes repeled) by the ship itself, and they must be "rebalanced" by a vertical magnet; sometimes called heelng error correction.   If you see a fancy restaurant  binnacle, open the side door and you will see the vertical tube for the vertical field magnet; sometimes the magnet is on a chain.

It is imparitive to do this correction otherwise it's like trying to balance a pencil on its point.  The card will get squirrlelly on some headings and appear stuck on other headings.  The challenge is on pedestal compasses without a vertical tube.  Compass adjusters get creative.  I have a nice part from Suunto (Finnish, long outa business) that looks like a hockey puck and hanges on the corrector bars in the bottom of the compass binnacle.  Sometimes you can drill holes into a wood plate the compass sits on and push vertical magnets into the holes. The trick: knowing which way to place the magnet and how far away.  Red end up?  Red end down?

Good resource: HO226 - Handbook of Compass Adjustment (from Defense Mapping Agency?).  Unfortuately, Chapmans is not much help for steel vessels.  Find a compass adjuster.

-- 
Robert S. Peterson
Great Lakes Compass
31 N Alfred, Elgin IL  60123  USA
847/697-6491
Compass expertise for Lake Michigan navigators since 1985
email: glcompass(at)astound(dot)net
web: https://www.greatlakescompass.com/