Attwood Tsunami MK2 1200 GPH 12-Volt Thred Manual Bilge Pump. Tsunami Mk2 the ONLY manual bilge pump that eliminates air locks. What makes Tsunami Mk2 so innovative is the patented X-Air Impeller. Its engineered performance forces air bubbles trapped in the hose and underside of the pump out of the pipework so that the pump will not run dry and burn out. This breakthrough technology makes Tsunami Mk2 the most reliable manual bilge pump in freshwater applications.