Just make a smaller 2 inch inside diameter bayonet locking ring instead. The diagram shows there is enough gap between inner and outer hulls for a bayonet ring
Then just make wtc attached to stern with two screws for easy removal for inspections and maintenance?
You're the engineer on this project so leave to you. The limber holes in hull are already done for you.
The exterior torpedo tubes are printed too but suggest maybe these could be made instead out of brass tubing and then you would be able to launch small electric torpedoes instead. I'll send you the tubes too for you to decide or if for nthing else sizing the new brass ones from the printed parts dimesons.
The hatches need work.
Steven
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