The type of ship referred to here is called a Clipper Ship.
Explanation:
Clipper ships were built for strength and speed. Strenght in term of their ability to carry cargo, defend themselves when confronted with pirates and or outrun enemy ships or the English ships which often patrolled the Atlantic.
Of course, any ship which had a need to outrun the British Patrols was most likely involved in illegal trades such as slave trade.
For those who were into legitimate trades such as the shipping and transportation of tea, precious metal and other international commodities became very rich as their time of delivery was reduced drastically in that time.
