It depends upon your mission orders. Look in the Radio Log, and see if you can find any time designation. Usually you won't be able to. Next patrol, pay attention to how long they tell you to patrol, and how large of an area. If you really feel the need to complete the mission, draw yourself a 50nm radius circle centered on that star with the binoclulars, and then stay within that circle. It might be 48 hours, it might be more, but with the stock game, it is usually 48 hours (continuous time, btw). Truth be told though, you don't have to complete any mission you are given. You will lose the points of completing the mission, which might be as high as 300 renown points, but in Stock is usually only 100-150 points. There are no penalties in the game, unless you sink a neutral or friendly ship. Since you have sunk quite a few ships, you are good to go back to home port and be welcomed as a war hero...
