As I have been travel down the ICW I have noticed that when running the engine I was increasingly getting lots of vibration. Yesterday when we pulled Reboot I discovered the reason. Like most boaters I have sacrificial zincs attached at various places to prevent galvanic corrosion of Reboot. One place is on the drive shaft. It turns out that the zinc, rather than decaying by shrinking in general had decayed on one side while leaving the other side intact. So I had this big off center weight attached to the drive shaft! We changed it out and hopefully the vibration will now go away.