Officers at the Royal Fleet Auxiliary (RFA) will launch industrial action short of a strike from Saturday in a dispute over pay.
Nautilus International members in the RFA voted overwhelmingly for action in response to a below-inflation pay offer for 2023/2024.
The union said its members have been hit by a real-terms pay cut of over 30% since 2010.
No credible offer had been made despite talks with the government, said Nautilus.
Nautilus said its members are expected to continue to respond to emergencies and to continue to work in full compliance with ensuring the safety of people onboard, the safety of the vessel and the safety of the environment at all times.
The union’s international director of organising Martyn Gray said: “This decision to take industrial action has not been taken lightly but underlines the strength of feeling of members at the RFA who are overworked, underpaid and undervalued and have faced a real-terms pay cut of over 30% since 2010.
“It is incumbent on all political parties to use this election period to affirm their support for our national defence and the Royal Fleet Auxiliary by committing to a pay rise reflective of the rate of inflation and restoring the pay our members have lost over the last decade.
“Nautilus will seek to work with whoever forms the next government to find a solution, but our mandate for action remains active until October and if a solution is not forthcoming in the early stages of a new government further action will be taken.”
