Do you remember the falling feeling in the pit of your stomach when the tach for your diesel engine suddenly shows the rpms falling, or surging and falling, or just acting erratically? Not a good time, on any boat. Problems with dirty fuel, water in fuel, whatever. You don’t want to be there. Protect yourself and your diesel by periodically changing the fuel filter, before there’s a problem. Here’s a good look at how to do just that: