Patent ID: 6895950

Claim:
A crossbow-type underwater gun comprising: a butt having a mechanism for blocking the rear end of a spear and a member for unblocking said spear, preferably a trigger; a longitudinal spear support element whose rear end is engaged in said butt, and resilient propulsion means comprising at least two bungee type side resilient cords whose front ends are suitable for being fixed to fixing elements and whose rear ends are suitable for engaging in at least one notch in the rear portion of said spear; the gun being characterized in that it includes a device for stretching said resilient cords, the device comprising: a moving head piece to which said first fixing elements can be fixed, said head piece being suitable for sliding along the front portion of said spear support element between: a rear position enabling said resilient cords to be engaged without tension in said notch; and an advanced position in which said resilient cords are stretched maximally when they are engaged in said notch; a rod, said moving head piece being suitable for sliding along said spear support element by moving said rod in its longitudinal direction, preferably parallel to that of said longitudinal spear support element; and a lever arm, said lever arm co-operating with said rod via a thrust and retaining device which makes the following possible: moving said rod in said longitudinal direction under drive from pivoting said lever arm; holding said rod in an advanced position corresponding to the travel distance of said rod resulting from said pivoting of the lever arm while said lever arm is returned to its initial position by being pivoted in the opposite direction; and thereby enabling said resilient cords to be stretched by performing a succession of pivoting operations on said lever arm between an initial position and a thrusted position.