Here are some links where you can learn more about lightning and how to protect your boat. I have a lightning rod on the top of my mast, and a large cable that runs into the water with a big copper plate on the end. I have a lot of cuts on the plate to increase the edge area, which is where a charge will dissipate. Can't use it while underway, but it's in the water while I'm docked or anchored.
http://www.kastenmarine.com/Lightning.htm
http://marinelightning.com/
http://www.lightningsafety.com/nlsi_...od_recent.html
http://www.lightningsafety.com/
I had more links, but a surprising half of them no longer work. Oh well, these should provide a lot of good information.