I have a copy of the Whitby tide tables so if you want sepcific dates, just ask. The large trawlers only unload at mid to high water but the smaller boats (cobles) unload their catches of crabs & lobsters at anytime of tide. The fish market where the catches go is only open on a morning. If you hang around between 8am and 10am you will see something being unloaded. If you go at a morning high tide you are not guaranteed to see a trawler unload as there may not be any trawlers in that day. There are large gates to stop the public walking onto the quay but it is a public right of way so no one can stop you. However, you'd probably get some filthy looks and a few choice swear words aimed at you!