Ferry in Okinawa

I’m travelling to Okinawa in late July/early August and I’m going to Tokashiki from Naha for a couple of nights. I’ve heard that if the sea is rough, the boats get cancelled and usually the Marine Liner is first to get cancelled out of the two. However, I want to book the Marine Liner because the times suit me better and it’s faster. Do you think this is risky and does anyone know if the ferries get cancelled often? I have a flight the next day so I don’t want to get stuck on the island. Thanks in advance