Period and new guy

So I’ve just recently started dating this new guy and we have a boat day planned for tomorrow but I started my period today and I am super heavy and clotting a lot and I’m worried that I may bleed through a tampon because I don’t know how long we will be out there. How is a good way to ask him how long we will be out there and how to let him know I’m going to need to make a few stops if we are out there all day without making it TMI for him?

I hope that makes sense.