What is this joint or part called

im creating a contained hydro power system. the turbine rod is going to go through part of the pipe and will need to come out probably both ends.

I'm looking for a piece that will seal that hole that the turbine rod went through but will also allow the rod to turn at any rate.

I'm pretty sure its rubberized too or something like that. I think they have something like this on marine vehicles. anyone know?

Some where in there you are going to have to have bearings on both ends or at least on two places on the shaft and if you ask at a bearing supplier, you can probably get sealed ball or needle bearings that will do both

you could use an "o" ring but the old way is called a stuffing box seal-

http://www.epm.com/packing_install.htm