[C320-list] How deep do I drill?

[Graeme Clark]

I’m trying to find the void with wiring harness for solar wiring
Manual says 14” back from edge of hatch cover. (Admittedly it states earlier hulls had harness in port side but as drawing is dated 93 and I have a 96 year and batteries are in starboard side I’m assuming it’s actually in starboard side on mine)
I’ve drilled about 5/8” deep. Manual says 3/16ths
Now wondering if harness never installed in my boat (maybe because destined for the grey overcast U.K.!)
How deep can I drill without risk of making a hole in the saloon or heads ceiling!
Thanks
Graeme
PS photo available at this link
https://ibb.co/kXvj2H


Sent from mobile: please excuse typos etc.!