If you like books about boats (or anything else for that matter) , it's always worth checking psbooks.co.uk to see what they list under "Transport". They are a remainder book shop - this month they've got (among others) a book on sailing rigs, and ww2 at sea in photos - including a featured photo of HMS Hood's Walrus from inside the hangar. If you buy a book from them theyl'll send you their monthly paper catalogue for a few months. All books at a fraction of the original published price.