The 12 crewmen, who are members of the Unite union, will refuse to act as masters and may not work overtime to cover annual leave on Shetland routes, the Shetland Times said.
Services to Yell, Whalsay, Skerries and Unst will be affected.
The action will take place each Wednesday morning until 4 March.
Runs to Bluemull, Bressay and Papa Stour will not be hit.
