page 40 0f the excellent year-book shows an addition of 20 to the handicap for a boat with a carbon mast compared with that for a boat with an aluminium one .Can someone explain why as surely all the boats at the top of the fleet have gone carbon ?

I think you will find this to be an error and should read -20.  This handicaps apply to the vintage wing only.

It is for the Vintage wing only and it is minus 20 on the Yardstick. Missed that on the proof obviously!