What does lombard guess to be the true situation with the motorboat?

Lombard speculates that the motorboat's absence is part of a larger scheme, likely indicating that someone has deliberately ensured that no escape is possible for the group on the island. He suspects that the lack of a functioning boat may be a calculated move to trap them, heightening the sense of danger and urgency among the characters. This realization adds to the tension and paranoia as they grApple with their precarious situation.