What penalties are there for Jenny Craig ships?

[dizzy]

I see you can build and rebuild ships that exceed their weight design. Often these four are the ones I run into, hope I didn't miss any:

slightly overweight
overweight
considerably overweight
and seriously overweight, which stops the build process as an error. I guess the ship would sink if it held a Jenny Craig weight-loss convention.

Search-fu failed me. So what game mechanics, if any, govern the different classifications of how fat a ship is?

Does it affect the chances a ship will exceed it's design speed?
Does it affect turn radius?
Acceleration?
Damage control for flooding/counter flooding?
Sinking faster?
Bathroom portholes being above or below the waterline?

I'd like to know the answers to these if any of you have them. Thanks!

[aeson]

Designing a ship overweight increases the likelihood of negative commissioning traits and imposes a flotation point penalty which becomes increasingly severe the more overweight the design is.