Well I thought I might have another Seabee here, but now I am leaning towards Watertite, mainly because of the dial.
This has the larger than some watertites, but I believe that this may only apply to theolder ones, and a much more complicated case. The outer bezel accepts the case back, which is quite deep, from below, and then the reflector and crystal and outer ring compress the crystal against the flange for a seal. Unfortunately the case is chromium plated and will have to be stripped and re-plated.
The last picture is with crystal removed, because it is a mess.