Huh ? I do not understand your question
Err, e.g. the fore spare torpedo IS directly beneath the deck planking in a water and pressure-tight container. You open the container and lift the torpedo out with a block and tackle fixed to the subnet deflector. You lower the torpedo to a small tripod screwed to the deck so the torpedo angle will match the angle of the forward torpedo room hatch in the deck. You let the torpedo glide into the forward torpedo room. Close the container, close the torpedo loading hatch, remove the tripod, remove block and tackle.
If you want to lift a swimming torpedo (life jackets fixed to it so it will swim) to the deck you simply surface the boat under it.
Greetings,
Catfish