Reading about the recent violent attack on a couple in Tobago Cays has made me start thinking about what kind of alarm system and other measures to install before I head out next time. Initial thought would be to install a laser beam across the companionway, which when tripped turns on a powerful light aimed directly at the companionway, along with a loud horn. This might startle and stun the boarders, and buy you a bit of time to assess the threat and use pepper spray if warranted (if it didn't already scare the boarders into leaving). I choose not to carry a gun, and am simply looking at alternatives to defend against an attack as happened in this case - which seems like the most common type that boaters face.
It's a sobering story in any event, in a lovely and heavily-visited area.
Max
http://www.noonsite.com/Members/sue/R2011-07-12-1