At best these things are semi-submersibles. They have to keep a snorkel and periscope above the water to function at all. They only have a crew of 3-4.
WWG1WGA
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
I think a good word for them would be deathtraps.