Mr Crow said: "This massive vote for action shows that RMT members are determined to stand united in the fight to defend their pensions and workplace rights on the CalMac services.
"The result will now be considered by the RMT executive and we hope that the company and the ministers will now seize this opportunity to give us the very simple and straightforward assurances we are seeking."
The RMT feared that the Clyde and Hebrides ferry routes would be broken up and sold off to private companies, with knock-on implications for workers' conditions.
Alex Salmond told MSPs during First Minister's Questions last Thursday that the Scottish Government has "no plans to unbundle the Clyde and Hebrides ferry service".
Mr Salmond said: "The tendering of the Clyde and Hebrides lifeline ferry services is required to protect these vital services."