In Lord of the Flies, why does Piggy suggest they create a clock?

In Lord of the Flies, a group of boys stranded on a desert island try to make sense of their surroundings and to find a suitable way to survive until they are rescued. However, the boys have very different ideals and plans for their time on the island and therefore there is a power struggle as Ralph and all that he signifies attempts to bring order and discipline in the absence of any "grown-ups' whereas Jack is preoccupied with hunting and his version of "fun." Ralph can only be a successful leader with Piggy's help as Piggy is insightful, resourceful and makes rational choices, based on what his "Auntie would do." Jack has Roger who supports everything he does but he is "furtive" and "forbidding" and he is the opposite of what Jack needs in preventing his impulsive and malicious behavior.

Chapter 4 is entitled "Painted Faces and Long Hair" and it is becoming apparent that Jack is attempting to set himself apart, seeing himself as "an awesome stranger" who is "liberated from shame and self-consciousness." Piggy, on the other hand, hasn't really changed and it doesn't even appear as if his hair has grown. He is always thinking of ways in which the boys can mimic the civilization he has been used to and manage themselves according to a routine because it is difficult for the boys to adjust to their new, informal "rhythm." Ralph makes fun of Piggy's suggestion but Piggy remains adamant that they can make sundials for everyone and then not only will they know what time it is but they can get "things done. So as we could be rescued." Piggy remains focused on the idea of rescue and is aware that not everyone is making a contribution to ensuring rescue. As seen later in the same chapter, Jack has allowed the fire to go out so that the ship on the horizon has no idea that the boys are even on the island.