They should make two covers for this book: One called "How to Design a Boat", the other called "How to Understand a Boat Design" because you are getting an excellent two-for-one deal here. If you are a boatbuilder, interested in designing your own, or just want to better understand (or even improve or customise) an existing design, buy this book now!
In this relatively small book, Teale has written an outstanding primer on the process of designing a small boat and what the considerations, compromises and key factors that influence how the boat will behave in the water are. The book contains all the necessary information - without resorting to differential equations describing compound curves or otherwise making it overly complicated.
Yes, there are some shortcuts in the proposed design process but, unless you're building a 200ft gin palace or really pushing the performance envelope, they won't make a blind bit of difference to the finished product - they do, however, make the rather huge difference between reading this 1/4-inch thick book for fun and pleasure and taking a 4-year university degree in ship design and mathematical analysis.
I've built a number of boats over the years and am currently working on a wooden blue water cruiser - I only wish I had came upon this book 4 or 5 boats ago and can't recommend it enough.