Rainer, sorry I misspelled Your Name, heres a little more, I was also speaking of, on a real U-Boat the Vent seals on the outside of the hull which allow water to enter and exit, The Boat I toured had several of them open, they were basically "Plugs" attached to a Cable that ran into the pipe the water flowed through, these were either operated by hand or in later boats electric power, remember in Das Boot where You see them turning wheels and pulling levers?.. These are what I was Speaking of. Now, Where do I Find a Model of a VII C U-Boat, Ive contacted several model co's and so far No luck!.. Thanx Again! KIP