your infinitely more likely to lose the motor as the boat sets in the marina unattended.....
powerboaters (and sailboaters) have been using outboards to propel their boats for many, many years in open water, hung from the transom or bracket mounted. loss of the motor is the least likely problem you may encounter, unless it has been mounted to the boat improperly.
in the last few years, with the development, improvements and fuel economy of the 4stroke outboard, a LOT of boats that would have normally in the past been outfitted with an inboard engine, are using big outboards for propulsion....
time and distance across an ocean has more potential impact on the safe passage of the entire boat and crew, than it does with how long the outboard will hang on the transom, providing its mounted correctly to begin with...
