public void spawnRateMedium()
    {
        if (spawnCounter > 300) {  
            spawnCounter = 0;
            double spawnRandom = Math.random();
            if (spawnRandom <= 0.33)
            {
                Boat b1 = new Boat(30,1,600,exit1);
                addObject(b1,800,61);
            } else if (spawnRandom >= 0.33 && spawnRandom <= 0.66)
            {
                Boat b2 = new Boat(20,2,450,exit2);
                addObject(b2, 800, 61);
            } else 
            {
                Boat b3 = new Boat(10,3,300,exit3);
                addObject(b3, 800, 61);
            }
            spawnRandom = 0;
        }  
        spawnCounter++;  
    }