Mclaren Clockwork Submarines

This monster has three ballast tanks , its own compressed air system , a clockwork timer to blow the ballast and a clockwork motor turning a coaxial gearbox for its two props . The colossal weight of this submarine is due to the fact that all my boats are dry hulls , therefore the bigger they become the heavier they must be to submerge. The tandem contra rotating prop design is awesome ,  it efficiently deals with the huge power needed to propel the boat , its slow to start but once up to speed its quick. The compressed air tank is charged with a bicycle pump and it can stay submerged for up to an hour.