Businessman Declan Ganley says Capt Duffy was "one of the most meticulous men I have ever come across"
Hundreds of mourners are expected to attend today's funeral service for Captain Mark Duffy in County Louth.
The father of two was one of four people on board the coastguard Rescue 116 helicopter when it came down off the Mayo coast on March 14th.
His colleague Dara Fitzpatrick was laid to rest earlier this month.
The search for the two other crew members - winch operator Paul Ormsby and winchman Ciaran Smith - continues near Blacksod.
Irish entrepreneur Declan Ganley was Captain Duffy's friend and former employer.
He told Newstalk Breakfast: "[Mark] was genuinely one of the most meticulous men I have ever come across [...] In his own personal presentation and conduct... a more professional man you could not come across.
"That he has gone in the heroic manner that he has, that he sacrificed everything for others, is a mark of the character of who Mark Duffy was. It was a privilege to have known him."