Who is Admiral James Sandecker from Raise the Titanic! and what is their importance?

Admiral James Sandecker is Dana's boss and Dirk Pitt's boss and the director of NUMA. He is the one who orders Dirk Pitt to England to interview John Bigalow. Sandecker is also on one of the salvage fleet ships when the Titanic is raised and is aboard the Titanic during the intrigue during the hurricane.