I try and follow C C Lynam's practice in 'The Log of the Blue Dragon': "For my part, I buy and read every record of actual cruising that I hear of or see advertised. The interest of such publications (which are astonishingly few in number) very largely depends on their simplicity and good temper ... constant grumbling, generally at the weather or the natives is another characteristic that spoils them". More than a hundred years later, many more books have appeared, some are very useful and even wonderful, worth having on the boat if you have the space and don't mind them getting damp. They have certainly been a great resource for writing this website. Of course you may be of the generation that prefers to have everything downloaded onto a tablet, but then you will miss the tactile and olfactory pleasure of real books. And the appearance of their spines in your bookcase, categorised by topic.
Here is my recommended reading list in the following sections: Logs and cruises, General guide books, Some quirky and other books about the area, Around the west coast of Scotland books, and Sailing directions.
And don't forget to have on board books about the birds, flowers, whales and dolphins, trees, and the seashore.