Who is Captain Nicholas Saltwood from The Covenant and what is their importance?

Captain Nicholas Saltwood is forty-fouryears-old and an experienced mariner. He purchases the Acorn in order to sail the southern seas. A two masted ship, the Acorn belonged to Sir Francis Drake before him. Thus, he was reasonably confident of his success. After his first voyage to Africa, he returns, sells his ship and buys nine acres on the Avon river for his wife. He names the property Sentinels and plants trees along the river that are the sentinels for generations of Saltwoods to come.