Adjusting a steel boat compass

[Gubbo]

I know this is quite an in-depth subject, but I am after some practical advice as to the best system for swinging my Silva compass on a steel hulled yacht.
The manufacturer's instructions are quite clear for the usual method in adjusting the N/S and E/W screws, but I also have the compensator discs to place either side of the card.
I am not sure at what point I should fit these and how I assess their effectiveness.
Has anyone fitted a similar compass recently ?
For info, the boat is 30' and kept in the northern hemisphere (UK). The compass is mounted on the wooden boom gallows about 2'6" above the steel coachroof. There are no ferrous metals, loudspeakers, toolkits, crew with tin hats etc near to it.
Advice appreciated
Gubbo

For details of my boat see www.sailpast.co.uk

 

[Guest]

You probably only need to adjust the two magnets if there is no other steel within a short distance. After adjusting it as best you can, use the computer program referenced below to do a deviation chart. It will give you an excellent guide to how far off it is at each point round the rose. If they are all less than a few degrees, then just keep the chart for doing corrections, otherwise re-adjust or add your disks and test again.

http://www.yandina.com/compass.htm

tech@yandina.com