Sir Alan Massey, chief executive of the Maritime and Coastguard Agency, made his remarks during a visit to the Greenock station to thank staff.
The station is closing today. Calls were re- directed to Stornoway and Belfast a month ago.
The closure, which follows the axing of Forth station in September, is part of a number of UK Government changes to the coastguard service.
Campaigners have been fighting to save Clyde – which, together with Forth, affects 42 jobs – while MPs and MSPs have raised safety concerns.
But Sir Alan said: "I want to reassure the public that what we are doing will result in a better service. We are not going to be putting people at risk and we would not be going through with these changes if we thought they would threaten safety.
"Our coastguards are highly professional. We have been helping them with training, with briefings and the transfer of that knowledge.
"For the past month we have had the teams from Belfast and Stornoway in place handling calls, with Clyde here as a kind of back stop."
Sir Alan added: "The staff have thought hard, and some thought, rather than stay, they have decided to stop their careers at this point.
"We have tried to find alternative jobs for all of them.
"I don't think anyone is particularly happy. Clyde has been under this threat of closure for a long time now.
"They have been extremely professional and hard-working, and I want to thank them for all they have done."