Not being high-tech in comparison, this method worked a treat for my washing machine tub DIY seal:
Yet another Honey-Do: Growling washing machine, Pt 1

It's been operative and used every other day for over two months w/o any sign of leaking!
My (unproven) personal hypothesis for the groove is the rougher its inner surface, the better the bite gets for the sealant.
Thanks for all you guys pitching in, particularly Frank S & ToolMaker51 for leading me to this nice solution!

Cheers
Johan