Thank for all input thus far.
I'm not sailing to Africa. They have real "pirates" there; motherships, multiple skiffs, auto-AKs. I'm sailing to the Carribean and Central America. There one (rarely) gets small bands of poorly equipped criminals and opportunistic fishermen. The worst case scenario is freelancing law enforcement or military. There is no religion involved, no thoughts of kidnap and ransom, just the desire for some easy looting and possibly raping. Where I'm going, pirates are more like muggers on small craft or swimming. Weapons are often knives or machetes, sometimes a rusty old shotgun or pistol. Favored techniques are approaching by stealth at night, approaching as enterprising fishermen looking to sell fresh seafood by day (or just asking for some drinking water). More often than not, the "enterprising fishermen" are just that. It pays to be careful though.
Pirates in Somalia, for instance, are popular; there is no tourism, and poverty is so crushing, anything to bring money into their communities is considered "cool". In Caribbean, Central America etc., cruisers spend LOTS of money at legitimate businesses. Piracy is very bad for these businesses. There are examples of vigilante justice in these areas, as the local businessmen "take out the trash".
The maritime shotgun goes without saying. I'm intrigued by the shotgun-only theory, but I confess my experience has been mainly with NATO rifles. I understand that an unrifled shotgun will throw slugs poorly, while a rifled one spreads buckshot too wide. Hitting close to target from a moving boat is challenging, no question. At least mine is a catamaran, more steady. A rifle holds appeal in that ammo doesn't weigh quite so much. My wife has never learned the art of packing light ;-)
As a US flagged vessel, I'm subject to US laws while in US or international waters. I don't get a free pass on the firearms I have, and can be inspected by USCG at any time. When approaching a foreign port, while still in international waters, one radios the port and informs port authority of a great many things generally. At this time one mentions that the boat is armed, and learns how will this be handled. If port authority says "no weapons!", try your luck at the next port.
Port authority tells you what to do: generally, they ask the nature of the weapons on board. In the case of normal non-semiautomatic shotguns, and sometimes hunting rifles, they are often happy to let you keep them in your onboard safe. They will slap a customs seal on your safe, to see if you were monkeying around with your weapons, inspected on departure. That's it. Only one country I'm aware of takes offense at carrying weapons in their waters prior to clearing in.
Mexico is a wretched place. Any weapon, even a single round of ammunition, within 7 miles of shore equals big prison time. No excuses, no anything unless you have a prior letter from the Mexican embassy giving you permission. I guess only the government/cartels should be armed. Venezuela is the most dangerous place in the area, with more of the freelancing police and military types there. The definitive site for piracy reports is
http://www.noonsite.com/General/Piracy . Unfortunately it is often unreported, or denied by local officials.
The Lee-Enfield is a fine weapon, and while it may be considered outdated by modern standards, it is by definition a military rifle.
In regards to marksmanship at sea, it is dicey. High-magnification scopes are essentially useless on a small boat. ACOGs and similar are not, just used as a reflex sight up until one can decide to change focus for an instant. Green laser works, better than red, because it lets you "walk" into the target and is more visible at longer range. A powerful rifle will probably through-and-through a small boat. Pursuers in a boat are lined up along the narrow hull, with the engine. Hitting a small boat at range is very difficult but can have devastating effects. Plus, one must be certain of their intent: firing warning shots towards the center of mass is criminal. Remember that these are not religious warriors or anything, just scumbags looking for an easy score. While the odds of a gun battle at sea are so small, I would just hate to have somebody able to reach out and touch me, while I'm trying to lob slugs back at them, with a slow reload and limited capacity.
There are some nice places out there: good weather, less expensive, friendly people. Probably five times as many drivers are killed by carjackers in the US every year, as cruising sailors are killed around the world by criminals. Nobody wants to be a statistic though. Vigilance is a way of life.
Fair winds!
