Something to think about...

[automatico]

Looking at the 7mm crown on a modern submariner with a gasket on the outside of the case tube, a gasket inside the crown cap, and two gaskets inside the case tube is impressive (the gasket on the outside of the tube is basically a dust seal).

But it all depends on one little gasket between the case tube and case.

Take a vintage seadweller with the same type of 7mm crown with a few detail differences...

That's fine and dandy but it all depends on the little bitty gasket in the helium valve and the tube to case gasket.

Some may say the case tube threads seal the case in addition to the gasket, but not much. The only way the case tube could seal is to have tapered pipe threads and it does not.

Loctite on the threads provides very little protection against leaks. Gasket sealer might be a little better.

What does this all mean?

The huge crown and all the gaskets are probably mostly BS (imho).

A 1980's GMT, OPD etc was rated to 100m with a 5.3mm crown. With a thicker crystal and the same crown/tube they would probably go 300m too.