You read correctly...I am writing about a square-rigged sailing vessel, not winter precipitation. A snow (according to Wikipedia, "[t]he word 'snow' comes from 'snauw' which is an old Dutch word for beak; a reference to the characteristic sharp bow of the vessel.") was a ship with two masts plus a "snow mast." The latter had a loose-fitted gaff sail, and was stepped immediately behind the main mast. In the diagram below you can see that the gaff sail (a four-cornered, fore-and-aft rigged sail, supported by a spar or pole called the gaff) is attached to a separate mast directly behind the main mast.
|Diagram by Refundpolitics for Wikipedia|
Snows were popular, especially in Europe, from the late 17th century, and were still to be seen in North Carolina one hundred years later.
This month's Ocracoke Newsletter is about Old Christmas in Rodanthe. You can read it here: https://www.villagecraftsmen.com/old-christmas-rodanthe/.