Today we're going to explore a few ideas for new carts. Let's continue our series with a movable version of a cistern: the Water Tanker - aka cistern on wheels.
A Water Tanker would be, as the name suggests, a mix between the cart and the cistern. An efficient way to carry large amount of liquids without resorting to the usual cart+boat options. It could be limited to water, but I don't see why not allowing any liquid to be placed in it tbh, like tanning fluid or tar...
Considering a Water Tanker would be a giant barrel on wheels, it would require the Wheel Wrighting and the Metal Working skills most likely.
To buil a Water Tank you would require mostly wood, as well as some metal (any metal, most likely). [Note: there would be the option of making this out of glass, but it would feel both unrealistic and impractical]
The Water Tanker should be more efficient at moving liquids than the current system of carts, barrels, and boats. A normal cart filled with barrels can bring up to 600 litres. That's 700 if you also lift a barrel, or 800 if you lift a boat with two barrels in it. That being considered, the Water Tanker should carry at minimum 1000 litres, but to make it worth a while I believe 1200-1500 would make for a fair amount.
Obviously using a large boat (snekkja or knarr) filled with barrels would still allow to carry more litres at once, but the Water Tanker would make for a good way to load and unload the liquid content of such ships.
Not sure if this is doable, but allowing for a Water Tanker to be filled directly at a well would make for an amazing extra feature. Although it would be nice to get such a feature, I'd rather have it without it than not having it at all.