Eustache  GOURDEL dit LONGCHAMP

Québec Généalogie - What is a 'dit/dite' name?  When the first settlers came to Québec from France it was a custom to add a 'dit' nickname to the surname. The English translation of 'dit' is 'said'. The Colonists of Nouvelle France added 'dit' names as distinguishers. A settler might have wanted to differentiate their family from their siblings by taking a 'dit' name that described the locale to which they had relocated. The acquiring of a 'dit' name might also be the result of a casual adoption, whereby the person wanted to honor the family who had raised them. Another reason was also to distinguish themselves by taking as a 'dit' name the town or village in France from which they originated. This custom ended around 1900 when people began using only one name, either the 'dit' nickname or their original surname.

Source: American-French Genealogical Society, Woonsocket, Rhode Island (www.afgs.org/ditnames/index1.html)

Eustache was a navigateur.
The navigateur, or navigator, was the person on board a ship responsible for its navigation — a set of tasks to determine the position of a boat or ship and the route to follow. The navigator's primary responsibility was to be aware of the ship's position at all times. Near coastlines, he had to avoid hazards by determining optimal routes depending on the shoals, the state of the tide, and the channels to follow. On the high seas, he had to be skilled in long-term forecasting in order to make the best possible decisions depending on the weather.
Source: tfcq.ca

A Journey into the Life of a Navigateur in 18th Century New France