being lost at sea is a kind of being lost & if a person is lost, then they need to travel to a location ->  if a person is lost at sea, then they need to travel to a location  if a person is lost at sea, then they need to travel to a location & if a person needs to travel to a location, they need to direct themselves to that location ->  if a person is lost at sea, they need to direct themselves to a location  if a person is lost at sea, they need to direct themselves to a location & the shore is a kind of location ->  if a person is lost at sea, they need to direct themselves to the shore  the shore is a kind of location & if a person knows the cardinal direction of a location, and their own cardinal direction, then they can direct themselves to that location ->  if a person knows the cardinal direction of the shore, and their own cardinal direction, then they can direct themselves to the shore  if a person knows the cardinal direction of the shore, and their own cardinal direction, then they can direct themselves to the shore & a compass is used for determining a person's cardinal direction ->  if a person knows the cardinal direction of the shore, and uses a compass to determine their cardinal direction, then they can direct themselves to the shore  if a person knows the cardinal direction of the shore, and uses a compass to determine their cardinal direction, then they can direct themselves to the shore & a magnetic compass is a kind of compass ->  if a person knows the cardinal direction of the shore, and uses a magnetic compass to determine their cardinal direction, then they can direct themselves to the shore  if a person is lost at sea, they need to direct themselves to the shore & if a person knows the cardinal direction of the shore, and uses a magnetic compass to determine their cardinal direction, then they can direct themselves to the shore -> if a person is lost at sea, and shows the cardinal direction of the shore, then they can use a magnetic compass to direct themselves to the shore