I was wondering about the mechanics of a sea blockade.

For instance, I was playing a game as Gandhi last night and I was isolated on my own, large island not far off the mainland. I went to war with Musa and surrounded his coastal cities with galleys and caravels. If a galley is sitting directly in front of a coastal city, does that not only block the citizens from working those tiles but also from any trade routes reaching that city by sea?

You cannot work a tile that has an enemy unit on it. When you use blockade, the blockaded area is shown.

I understand that, which is why I said that you can't work tiles with enemy boats in them in my first post.

My question was whether or not it cuts off trade routes as well.

Also, I'm using 1.52 vanilla civ, so I can only assume the blockade that you are talking about was added in an expansion. My blockade was not an ability with an AoE but just a boat sitting in front of a city.

No, simply parking boats out in front of a city won't cut off trade routes. The Blockade ability was added in BTS (or possibly Warlords, I forget), which -does- cut off trade routes for cities in the area of effect. I'm not sure but I think it also negates working the water tiles in that area, I haven't checked.

Added in BTS.

'Blockading' ports in Vanilla just stops ships from coming out of them.

I'm not sure but I think it also negates working the water tiles in that area, I haven't checked.

Indeed it does. Privateers are excellent for that (and they plunder gold:)). I have caused size 20 coastal cities reduced to size 5 cos it was cut off from all its sea tiles. Its a good way of crippling the enemy. Mind you if using a privateer (non wartime), you cut yourself off from trade routes.

I'm pretty sure you can do it in Warlords, too. I hope, because in wars I usually blockade the costal cities. All of them.

I'm pretty sure you can do it in Warlords, too. I hope, because in wars I usually blockade the costal cities. All of them.

Nope, can't.