Sealant question

[bromleybysea]

I am replacing a couple of Ventilite vents on the coachroof. The deck is teak over fibreglass though I intend to cut back the teak and epoxy in a ring of something inert- probably tufnol as I have some sheet to hand. Ventilites appear to be polycarbonate- what would be the best sealent- I originally used Sikaflex but I suspect it might be better to use a non-adhesive sealant- any suggestions?

 

[Boathook]

Arbomast BR is now my preferred sealant. Non setting grey colour and does not like sunlight so no good for clear perspex, etc. Apart from the sunlight issue does a very good job.