Apparatus, an arrangement and a method for locking an underwater hatch or other removable structure

An apparatus for locking a lockable underwater hatch or other removable or turnable structure (6) in a vessel or other floating structure, the apparatus comprising

• a locking rod (2), having a first end (2′) that is attachable in an articulated manner to a hull (7) or other structure of the vessel or other floating structure, said locking rod having a second end (2″), adapted to engage a surface of the lockable hatch or other removable or turnable structure (6) in a locked position,
• a turning mechanism (3) comprising a first part (3′) having a first end and a second part (3″) having a first end, where the first part and the second part are, at their first ends, attached to each other in an articulated manner, wherein a second end of the first part (3′) is operably attached to said locking rod (2) in an articulated manner and a second end of the second part (3″) is attachable in an articulated manner to the hull (7) or other structure of the vessel or other floating structure, and
• an actuator (4) that is operably attached to said turning mechanism (3), such that said first end (3′) and said second end (3″) are turned by the actuator so that said second end of said locking rod (2) is moved toward or away from said locked position;
• wherein said locking rod (2), turning mechanism (3) and actuator (4) are configured such that said actuator (4) does not require operational energy to maintain said locking rod (2) in said locked position.