I agree with Joel on the insurance approach to the issue on this and the other thread.
As far as the door goes, the hinges can be removed from the port side or a thief can force the lock with a crowbar, so about the only way to block the door shut would be to place a flat metal bar over the door with padlocks on both sides and hasps that are protected. Not foolrooof, of course, but it might discourage them enough to move on to another, easier victum.
The burglar alarm is tricky to install and temperamental in use and its necessity and advisability depends on the relative dangers where you leave the boat.
In my case, the marina has night security patrols and almost never has break-ins, except for one forray of stereo burglars to rip off all the expensive high powered sound systems out of the wakeboard and ski boats. Came in by boat. Never caught.
There is perhaps a very small outside chance someone who really wanted a C-Dory coluld come in and steal the entire boat, but they'd have to have a suitable trailer and take it out of the local area to use or sell it. Would take some planning and organization. Most local rip-off artists are crank-heads and can't think that far ahead.
Locking loose things up inside the cabin and covering them up out of view eliminates most "crimes of opportunity" from non-professionals (fellow boaters).
In marinas where there are live-aboards, making friends with them so they will casually watch your boat and recognize strangers would be invaluable. The same for fellow berthers with occasional usage, but to a sopmewhat lesser degree.
Pay for the insurance and realize you can not only replace anything but use the opportunity to upgrade your boat and / or equiment.
Life's to much fun with a C-Dory to lay awake at night and worry about something you can't entirely control. Dream instead, if you will, of how you'd replace the gear that some idiot made your insurance company pay for. (Get your deductable in an acceptable range to make this work, of course!)
Joe.
