Talking to a friend about boats and the subject came up about testing a boat for corrosion.
The first thing a technician would do is a visual inspection, he would look at all the anodes, terminal strips, battery compartment, electrical switches, engine, prop, out drive, under flotation and fuel tanks to name a few areas. The fuels tanks in the X.X. Boats are knows for having corrosion problems.
If you know what to look for you can do a visual survey. All you need is a flashlight, note pad and a camera. Take several high quality close up (12 inches) and distant pictures of everything and note there condition. If your have a slip you may want to have a diver inspect the bottom for problems.
It can take a less than a week or several years to cause hundred if not thousand of dollars of damage.
Having documentation and pictures you can show a technician can save you a lot of money. Case in point; your anode are eroding away knowing how long it took will help the technician decide if all you need is to replace the anodes or there is a more serious problem.