[PSUBS-MAILIST] Conning tower Problem

I figured out a way around my conning tower "problem" . There has been a concern that I am getting too large a diameter conning tower in relation to my hull diameter. The consenus is that the smaller the conning tower diameter in relation to the hull dia the better. But I was counting on that area for some comfortable room for my upper body. So what i'm thinking about doing is making a very minimal diameter transition with a 20" diameter hole into the main pressure hull, but then once i'm out above the hull 4" or so then weld a donut which will bring my conning tower out to a 30" diameter ( same as my main pressure hull). So where my waist is it will be 20" in diameter but I'll have more freedom of movement for my upper body. The donut itself would be 20" on the inside and 30" on the outside, so 5" wide. If the material was quite thick or if I welded a box type gussets that area it would not be subject to any unusual stress.