Gundalows, perhaps due to the limited time available, were relatively primative battleships; basically flat bottom cargo vessels topped with cannons. They were built and used by both American colonists and the British during the early part of the American War of Independence.
In this painting by James A. Flood, the gundalow Boston (also historically known as the first USS Boston) is depicted sailing with other vessels of the Lake Champlain squadron in late September of 1776. The squadron is headed south along the Vermont shore, with the wind on the port beam.
USS Bostons Link: USS Boston Shipmates
From USS Boston Shipmates home page, click BOSTON Histories, then select Gundalow 1776-1776