Got a 2 inch hairline crack in the bottom of the bathtub. Seems to be watertight but want to get it patched up.

Seems to be a choice of repair tape, or a kind of resin kit which involves mixing two parts together to form a resin which gets spread over the crack wtih a syringe

https://www.youtube.com/watch?v=h8vyX4GJaus

Anyone else care to suggest the way forward? Do I need to drill at both ends to stop it spreading? I'm reluctant to drill whilst it's still watertight. The bathtub is white fortunately so I don't have to worry too much about colour matching.

Thanks
Jon