Lindsay Evans from Putney and Bob Baker from Tilbury are among the crew members on the Great Britain boat.
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Singer paid emotional tribute to victims of the Manchester Arena attack, saying 'it's awful... and whatever you can do to help, you should'.
Holidaymakers reported long queues at check-in desks at the airport on Friday morning.
The events were cancelled on Wednesday in the wake of the Manchester attack to allow police officers to be re-deployed.