Hi they are flap valves. I might risk sounding stupid here but we,ve just found two plugs that go in the holes on the floor of the boat so that will stop the water coming through. It shouldn’t have filled up so quickly though so I,m thinking one or both of the valves need cleaning or replacing which is something we can do. The excess water should also come out when we plane. Anyway think the problem is solved know but thank you for your replies!