A submarine's net cutter is a device mounted on the bows of some naval submarines to cut through anti-submarine netting.[1] Some net cutters are powered by explosives.
References
^NAVY DEPARTMENT OFFICE OF NAVAL INTELLIGENCE (06 1918). "German Submarines in Question and Answer". WASHINGTON GOVERNMENT PRINTING OFFICE. http://www.history.navy.mil/library/online/onipubno32.htm. Retrieved 2009-03-12. "What is the characteristic appearance of a "U. B." boat? One gun only mounted close before the conning tower. Deck sloping down aft to the stern, where it is awash. A net cutter is mounted at the bow..."