I have 35 privateers blockading 32 cities, the spare privateers picking off triremes and nipping back into the ocean to heal when necessary. Each city yields 2 gold per turn, with one exception: Delhi, pop. 17, yields 6. Why ?
Not that I'm complaining, mind you. But there's also Yasodharapura, pop.15, among the 2-gold cities, which is also a good-sized capital, and I can't see why Delhi hands out three times the gold.
Alas, things won't continue in this happy vein for long. Caravels are appearing, and one rival is building a frigate . . .

If I recall properly, you get the money that the city would have gotten via its trade routes. It's quite possible that that city is just the best trade route income city that they have, therefore they are making that much more.

I dont think you get all money the city has from its routes - the usual 2 - 3 gpt are to few - its more like the yield of one trade route...

But basicly its still true - the amount of plunder depends on the value of trade routes... So those in Delhi are more valuable...

Perhaps Temple of Artimis there ?

I may be mistaken, but I thought I read somewhere that the Privateer would blockade all of the cities within its zone of control. Perhaps that particular privateer is plundering the trade from mulitple cities?

Yea it will blokade all cities, but in my experience, the plunder is the same with one or more blokaded cities... Might be wrong tho - i dont use Privateers that much...

I routinely blockaded individual cities until I noticed if you blockaded an isthmus or the straights of gibraltar on an Earth map you get multiple gold from different cities whose traderoutes I had blocked as a result.

the ZOC thing is true!

More data, but still no answer to why some cities yield double the plunder.

1. A privateer blockades all the cities within the 7x7 tile blockade zone, including any land routes, and no trade can pass through the blockade zone.
2. Plunder from each city is reported separately.
3. If a city is blockaded by more than one privateer, it yields only one lot of plunder.
4. Basically the plunder is 1 gold for each trade route the blockaded city had, regardless of the value of the various routes.
5. For reasons yet unknown, a few cities yield 2 gold per trade route.

For example, Aksum (pop.15) was trading with 3 of my cities and getting 11 commerce from each: blockading brought me 6 gold per turn. Addis Ababa (pop.12), also Ethiopian, also trading with 3 of my cities at 10/9/9 gold: blockading brought 3 gold. This made me wonder if blockading a capital brought a bonus, as Delhi also gave 6 gold from 3 routes, but London gave just 2 gold from its 2 routes. I'm baffled.