public void sinkShipOnTimer(){
        // sequence to sink a ship
        if(sunkShip){
            if(sinkingShips.size() != 0){
                for(int i = 0; i<sinkingShips.size(); i++){
                    if(sinkingShips.get(i).getSunk() == true){
                        sinkingShips.remove(i);
                    }
                    else{
                        sinkingShips.get(i).sinkItself();
                    }
                    
                }
            }
            else{
                sunkShip = false;
                sinkShipTimer.stop();
            }
            
        }
    }