[PSUBS-MAILIST] Conning tower hatch O-Ring

[via Personal_Submersibles]

Hello Psubs group,

I would like to ask the group where I can purchase an O-Ring for a 24" conning tower hatch ring.  I also need to mill the slot in the hatch ring and would like to know the width and depth of the slot.  I've heard some folks recommend a dove tail slot for the O-ring. 

Many thanks for your advise.

Mark...