I've recently been experimenting with an interesting design. I carve away the front layer of rock in the cliff face and fortify it, creating a bunker of sorts, eventually to place siege weapons in. Behind it, I have a moat about three tiles wide. All the bridges spanning the moat should be retractable, but internal ones to access the bunker should be left fine.
I've never actually lived long enough to face such sieges, but I'd like to prepared for when I do.
I've been encountering a couple of problems to this end, though, both pertaining to my moat. The first game I tried this in, I played very seriously, and did very well. I was quite pleased with the results, and in the end of the second year the moat device seemed finished. When I activated it, however, I'm not quite sure what happened... but the water burst through nearly my entire fortress, including the forward bunker where the lever was held, and also flooded the entire world! I was most unhappy with this, and vowed to figure out how to make the moat work before I played again.
The next time, I went straight for constructing the moat, to make sure I could get the process right. I theorized that perhaps the flow of water related to the settings of the doors used to contain it ("Pet passable" used to be "open", perhaps that let the water through?). I set a number of doors to a variety of settings along the flood path, to see which would let water through. However, the water was perfectly contained by all of them. This really confused me, as I made quite sure any holes were perfectly plugged the previous time. A bug?
Regardless, another issue I encountered once I had my now perfectly contained moat: I couldn't bridge it. I had built a number of bridges prior to activating the flood, but they were all buried underneath the water. Further, the game wouldn't let me build new bridges over the now flooded area. How do I do this?
Thanks.