What is a long boat?

We read about the longboat in tales of pirates and old sailing ships. The captain and a few chosen men, we read, set out to explore the little island in the ship's longboat.

The old sailing vessels carried several smaller boats on deck, much as the big liners of today carry life boats. The longboat was the largest of the boats carried on merchant sailing ships. Like our life boats, it was equipped with one or more sets of cars.