If you want to better understand the big iron toiling under the deck of you sportfish, pick up a copy of the Complete Guide To Diesel Marine Engines by John Fleming. The book takes you through the ins and outs of diesel power in terms even a landlubber could understand. It explains the hows and whys of diesel engines, but there's also a chapter on the basics of trouble-shooting and another on selecting the right engine for your boat. For the die-hard, there's even a chapter on the mathematics of diesels. If you want a solid understanding of how a diesel operates, this is one hands-on guide to bring aboard.