Ascanius; or, the Young Adventurer

A good English-French dictionary of the 18th century is essential.

Dictionnaire français-anglais et anglais-français, abrégé, By Abel Boyer Volume 1 and 2

ledit, ladite, pl lesdits, lesdites adjective the aforementioned or the said

Also dudit, desdit talking about different laws and articles that have been passed:
il a été fixé par décision dudit Conseil le 5 juillet 1745.

‘Icelles,’ old term for’celui-la,’celle-la or ceux’ only used in law.

Nautical terms are particularly difficult and the Glossaire sur les navires helped.

Nautical terms, in English and French with useful tables

The French brasse is equal to 1.624 metre, or very nearly 5 ft. 4 inches. An English fathom is equal to 1.829 metre=6 feet. Lieue = League; Mouillage = mooring; Ancre = anchor, Amarrés = docked or tied off.

Ancient French texts can be deciphered with the help of Frédéric Godefroy's ten-volume series

Dictionnaire de l'ancienne langue française et de tous ses dialectes du 9e au 15e siècle