Workers are being laid off at the BiFab fabrication yard at Arnish in Lewis.
Thirty-five employees are being laid off on Friday and 15 more will lose their jobs over the next few days.
Arnish was brought back into use in March to manufacture parts for an offshore wind farm after being mothballed for about a year.
The contract has now come to an end and no further work is immediately available, leading to the job losses at the site.
There were warnings of the lay-offs in October.
Unions said at the time that news of job losses came as a "major blow" to the workforce.
The Scottish government said it would provide support for any staff affected.
BiFab, which also has yards in Methil and Burntisland in Fife, has previously received help from the government to avoid the threat of administration.