I took early retirement in 1987, and my wife and I took off from Seattle on our sailboat. We have just recently returned, 2 boats and 13 years later. We've logged about 75,000 miles, ranging from Alaska to Mexico, to Australia, New Zealand, Indonesia and Singapore. We've spent the last 6 years in the Caribbean and Central America. This past year we sailed through the Panama Canal and up to Seattle nonstop (5,330 miles).
You have to think carefully about the situations when you might use a gun. In my opinion, most of the above scenarios belong in some action flick. They are not realistic. You are not likely to run into drug smugglers or people at sea who want to kill you and steal your boat.
Your main security concerns, in order, will be:
1. someone who wants to steal your dinghy.
2. someone who wants to steal something off your boat.
3. someone who wants to render you or your wife bodily harm, rape, pillage, robbery, mayhem, etc.
The first is extremely likely to occur in any country, and the best defense is to haul your dinghy up on the boat every night AND to get a BIG chain to lock it when you take it ashore.
The second is hard to guard against when you aren't on the boat...but being circumspect on where you anchor will prevent or minimize this.
The third is the stickler. You are legally required to declare any firearms when you clear into a foreign country. In most cases you will be asked to surrender them. You can then pick them up when you leave the country. So they are not going to be on the boat when you need them...if you declare them.
In the beginning I elected to carry a S&W Chief's Special. I never declared it. I kept it well hidden, and it was small enough that I could slip it into the pocket of my shorts. Only twice did I ever bring it out, and fortunately I never needed to use it.
This, however, made me extremely nervous everytime we went through immigration/customs. Because if it had been found, the authorities could have confiscated my boat and thrown me in jail.
I eventually decided it was not worth the hastle and quit carrying it. We just decided to avoid areas where there were potential problems (like Venezuela 2-3 years ago when their economy was in the cellar).
By the way, in all this sailing we lost 2 items. In San Blas, Mexico, someone stole one of our oars (he left us the other one so we could scull back to our boat).
In Fiji a kid took the American flag off our backstay. I took that as a back-handed kind of compliment, since Fijians seemed to love America.
Cheers,
Ten Man