When the ship drops anchor at Falmouth, why do they decide to drop anchor outside of town?

When the ship reaches Falmouth, Joel Sargent instructs the captain to drop anchor outside of the town so that they might make use of some grazing land. Joel Sargent has the children cut grass for the livestock to eat on ship. During this time, the children also pick wild strawberries to supplement their diet of bread and cornmeal pudding.