Stuffing Tube Installation

I am using a 1/4 ? stuffing tube in a flex shaft application. I want to use a sleeve that penetrates the hull. What size sleeve is required to fit over the stuffing tube snugly.
For water tightness I will solder where they overlap , this will allow me to have the ability to remove the stuffing shaft for replacement and not effect the hull penetration .
Your input would be appreciated.

If it's KnS brass tube, 5/16" is the next size up that will slip over a 1/4" tube. I do the same thing with sleeves to make it easier to change tubes in the future if necessary. No need to solder. A light smear of silicone as the inner tube slips into place is all that's needed to keep the water out.

Thank you for the info the silicone is a much easier method.