I know nothing about navigation restrictions but
draft = 2.5m is likely to be o.k. and height =
about 8m is likely to be o.k.

I designed a few vessels for the Caspian with these
dimensions and they were going to be delivered on
their own bottoms through this canal system. No
mention of air or water draft restrictions during the
design work (and the company I worked with would
have known)

thank you evan for the information, it's so rare to get information
first hand like that. i would think that the canal would be pretty big
too, because i understand it is used to transport big cargo ships
to/from the caspian sea and out into the open ocean. how big were the
ships you were working on, were those big cargo or fishing vessels ?
thanks again!