Dock in canals

[dooohhhh]

Is it possible to place docks inside a canal??

I have an oil rig and created a canal with locks to an oil refinery.

At the end of the canal there is a created area 4X3 so the ship can turn around but the game will not let me place a dock as it says the site is unsuitable.

Can anyone help?

http://img35.imageshack.us/img35/1384/rrc.bmp

[planetmaker]

they need be built on a slope. Thus terraform a bit so that you have a slope which goes down to the water. Same topography as you can build them on sea cost.

[dooohhhh]

Thank you