Mary Lacy (c. 1740 – 1801) was a British sailor, shipwright and memoirist. She was arguably the first woman to have been given an exam and a pension from the British Admiralty as a shipwright.

Lacy was born in Wickham, Kent in 1740.^[1] She became a domestic servant, aged twelve.^[1] In 1759, aged nineteen, Lacy ran away from home dressed as a boy.^[2] Using the name William Chandler, Lacy worked as a servant for a ship's carpenter of the British navy.^[2] William was her father's name and Chandler was her mother's maiden name.^[3] She then studied as an apprentice to be a shipwright in 1763, going on to successfully complete the apprenticeship.^[2] In 1770, she took her exam as a shipwright, arguably the first woman to have done so.^[4] In 1771, however, she was forced to stop working because of her rheumatism, and applied for a pension from the Admiralty under her legal name, Mary Lacy, which was granted. She published her memoirs The Female Shipwright in 1773.^[3] This was reprinted by the National Maritime Museum in 2008.

On 25 October 1772, at St Mary Abbots, Kensington,^[5] Mary Lacy married Josias Slade, a shipwright, of Deptford, Kent.^[6] That same year, Mary gave birth to her first child,^[7] Margaret Lacey Slade, who was baptized at St Nicholas, Deptford, Kent, on 29 August.^[8] Their other children were Josias Slade (1775–1777), Mary Slade (1777–1777), Josias Slade (1778–1781), Elizabeth Slade (1780–1780), and John Slade (born 1784).^[9]

In 1775 Mary petitioned for her husband to be granted a servant because of his 16 years' service as a shipwright.^[10] She had also applied unsuccessfully before Lord Sandwich for her husband to succeed Thomas Boyles, who lined the stuff for the Sawyers at the dockyard.^[10]

Mary died in 1801 and was buried at St Paul's, Deptford, Kent, on 3 May 1801.^[11][8] Her husband, Josias Slade, died in 1814 and was also buried at St Paul, Deptford, Kent, on 13 February 1814.^[12] In his will and codicil, he only mentions his son, John Slade, and daughter, Margaret, now wife of Joseph Ward^[13] (Margaret Lacey Ward died the following year and was buried at St Paul, Deptford, Kent, on 23 April 1815).^[12]

A chapter in Suzanne Stark's book Female Tars: Women Aboard Ship in the Age of Sail features Lacy's life in eighteenth century England.^[3]

• The Female Shipwright. National Maritime Museum. 2008. ISBN 9781906367015.