Engineer Quest: Enigma F

Engineers are a very inquisitive bunch. They love riddles too, like this "Enigma F" quest. 

Fastest on a full belly

The riddle this lady engineer offers you starts like this:

"I'm fastest on a full belly, and it sounds like I'm going cheap. What am I?"

Immediately you think something food-ish. But then, it's the thing that ate the food. Maybe... a train? Or a ship?

But no, it's not the oil harbour, nor either of the shipyards.

A full ship

Accessing the quest in your Questbook offers you a clue.

"What makes a ship go fast when it's full?"

Well, wind, of course. But seeing as we don't own any buildings that produce wind, lets take a step back.

The wind is caught by sails, and sails are made by...

Yes ma'am, the sailmaker!

Just click on a sailmaker (ANY sailmaker, even the ones of your competitors are allowed!) to finish this quest and retrieve your easily earned reward.