For anyone with an older Viking with the solid roof hatch needing replacement you will find that the curved shape makes it impossible to fit an Houdini hatch out of the box.However by using a flat sheet of ply and fitting a frame underneath it allows for the angle of the cabin roof in two directions the hatch will remain un- twisted and weathertight. Coachbolts compress the frame to fit then mastic and paint to finish.

(Many thanks to Mike for his kind permssion to include his © photos and text on this site)