The adjectival use of "jury", in the sense of makeshift or temporary, has been said to date from at least 1616 when according to the 1933 edition of the Oxford Dictionary of the English Language it appeared in John Smith's A Description of New England. It appeared in Smith's more extensive The General History of Virginia, New-England, and the Summer Isles published in 1624. The phrase "jury rigged" has been in use since at least 1788.
Two theories about the origin of this usage of "jury rig" are:
Depending on its size and purpose a sail-powered boat may carry a limited amount of repair materials, from which some form of jury rig can be fashioned. Additionally, anything salvageable, such as a spar or spinnaker pole, could be adapted to carrying a form of sail.
Ships typically carried a selection of spare parts (e.g., items such as topmasts), but at up to 1 meter (3 ft 3 in) in diameter the lower masts were too large to freight spares. Example jury-rig configurations include: