[A Navy Vet]

"I could be wrong, but I don’t that is the screw, rather I think those act as dive planes and rudders."

Same here. You can see a covering where the screw would go.

[editor-surveyor]

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>> “I could be wrong, but I don’t think that is the screw, rather I think those act as dive planes and rudders.” <<
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You have to be correct.

They are mounted to individual shafts that protrude through the hull.

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