Reddit mentions of Yachtmaster for Sail and Power: A Manual for the RYA Yachtmaster® Certificates of Competence

The RYA books are good, but better exists once you reach Yachtmaster level. The RYA's Yachtmaster material is far too brief, or at least it was for me when I was doing it.

I never get on a boat without my Reed's Skipper's Handbook. Truly essential. Yachtmaster for Power and Sail got me through my exam first time and I didn't get asked anything that wasn't explained clearly and concisely within it.

https://www.amazon.co.uk/Reeds-Skippers-Handbook-Malcolm-Pearson/dp/1408124777

https://www.amazon.co.uk/Yachtmaster-Sail-Power-Alison-Noice/dp/1472925491/ref=pd_sim_14_14?_encoding=UTF8&psc=1&refRID=1SZTBHGP5TBDENET1P26

Unfortunately there are no tricks. But all it needs is a bit of practice. It looks complicated at first but really is rather simple. And remember that it is always the same steps you have to do. What helped me is writing down these steps on a clean sheet of paper.

 

Maybe one of those videos can help also help you, not sure how good they are though:

https://www.youtube.com/watch?v=IfkwKTyYqeI
RYA Day Skipper: The Height of Tide
Leith Nautical Sailing Academy

https://www.youtube.com/watch?v=793F-Ha4T2U
RYA Coastal Skipper: Secondary Port tidal height corrections
Leith Nautical Sailing Academy

 

And this book also helped me with my theory. It has step by step instructions for all tidal calculations
Yachtmaster for Sail and Power Hardcover
by Alison Noice
https://www.amazon.co.uk/Yachtmaster-Sail-Power-Alison-Noice/dp/1472925491

 

The secondary ports here are subordinate stations btw.