Cargo Ship Dock

Thanks for answering. Hope it's a huge amount of money because I am always low in money! Just 6 hours to have my harbour completed!

And so far the item count is really low, (like 2 or 3 items to fill a pack) so you could get a gold key every 6 hours without much trouble, (immeditately fill and wait 6 hours for the next one). Just set a 6 hour timer.

Once you unlock the Disaster building, the cargo dock becomes less important; I find that the prices gives for loading the items on the ship are less than I can sell for in global, and you will need many of the same items to rebuild the buildings destroyed in the Disaster missions. You also get a lot more keys from the Disaster missions, and you can start a new one as soon as you finish rebuilding the buildings destroyed in the last mission. 

However it is still well worth the $10,000 investment if you aren't agressively selling in the global market, or if you are camping at a level below 90,000 population and want to get the education or trasnportation buildings. They offer a big boost in population, and the gold kay you get from each cargo ship filled will be needed to purrchase schools or transport buildings.

The coins you get from the Cargo Ship are pretty irrelevant. It's the Golden Keys that's the reason.

How many items in general do you need to complete a Disaster Mission?