Dan,
Don't rest too easy I have a friend that flipped my 17' alumnium with a 70 horse johnson upside down! It was the crazyiest thing ever. Happened at Talley Bend boat ramp. The worst part of it all, he had the trailer backed into the water and was trying to load the boat when it happened. It was a mess, I lost my trolling motor, motor cover, electronics, several, several, several jigs and a handful of rods and reels. It happened on April 1st and I like to never convince my dad to come help!!! He just kept saying, "Yeah, your boat is floating upside down. I really believe that."
The real reason to carry insurance is more than just the lower unit. If you sink a boat the EPA will make you remove it, of course with specialized people. They then stick you with a great big fine for every day the boat is in the water. There is no more of the "if it sinks we'll just leave it at the bottom" stuff.
After the boat flipping over incident I went to my insurance agent and said cover me for everything. Told her if I had a problem I was going home and she would have to take care of it.
Brad
Can You Find, "LIMITVILLE!!!" :D