fitting a hand grab rail

[dilly]

Hi there I have a moody 34.and would like to install a long hand rail grab under, the starboard window to stop the head lining sagging. There is one fitted to the port side, can any one tell me how much depth I have to play with. And screw size I will need if I tap it I can hear wood thanks Dilly

 

[LadyInBed]

Normally there are battens epoxied to the GRP 'roof'.
You should take off the head lining and investigate first.