I'm with Okta8 on this one. The counter balance in towards the North seeking pole and thus the CoG is slightly removed from the Pivot point. Whilst heading East or West the CofG is 90* to the direction of travel. When you accelerate/decelerate the CofG has inertia and of course want to continue in its previous direction which gives us our apparent turns to the North/South. This offset CofG is also responsible for the under/overturning effect during turns...INERTIA!!
I demo a full 360 turn at rate1 and stop every 90 degrees to show how the compass is slow or fast and that the errors between DI and wet compass are nil when arriving on E and West and maximum when arriving on North and South. Whilst heading East/West I raise and lower the attitude to demo acceleration errors.
Then its on to the practise.
ONUS Overturn onto North and Underturn on to South.
Select reference heading
Are we turning onto North or South?
Do we underturn or overturn?
By how much?
What heading will we rollout on to give us our reference heading?
Lookout
Rate 1 turn
Rollout
Let compass settle down.
How did you go?
Fine tune heading using 3*/sec i.e 10* off = Rate 1 turn for 3 seconds.