I read somewhere that they are very well equiped. I think I remember something about grappling hooks launchers or something along this lines. But, I can't find anything to back that up.
Well, I've read the recent news on how crews barricade themselves in the engine room. So heres my problem with the pirates boarding a ship. If it were me as El Capitan I'd wait I'd wait until they pull up along sides, fire their lil grappling hooks and depending on what side of the ship they are on I'd simply order the helmsman to put her "hard over" in that direction.
Simple really 1 lil skiff with a handful of pirates Vs. a cargo ship weighing ....umm ALOT = no more pirates

I really dont understand WHY this isnt done already. I know it takes a while to turn those big arsed ships but still, you should be able to take them out. Especially if the ship is equipped with bow thrusters. I dont know if all of them are but IIRC I saw a documentary of Discovery awhile back on building the latest gen of cargo container ships and they are soo big they pretty much have to have bow thrusters so they can turn alot sharper and quicker.
Also whats the top speed of these cargo ships? They may not be able to outrun a skiff but its not like the pirates are using a high performance cigar boat, just a skiff with 1 outboard is all I've seen. So my thought is even if they cant outrun the skiffs a large cargo ship moving at flank speed would create one hell of a wake! I personally wouldn't want to try and board it while my lil skiff is flopping all around and banging into the side, add to that the idear of turning into the skiff again = squishy pirates