The crew were on their way to take part in the Dubai-Muscat yacht race
A yachtswoman who has worked with the skipper of a yacht crew held by the Iranian navy has said he is "very skilled" and would be coping well.
The five Britons are being held after the Volvo 60 yacht they were sailing was stopped on 25 November.
Hannah White of Lymington, Hampshire, said she had worked with skipper Oliver Smith, 31, of Shirley, Southampton, for Team Pindar in the Vendee Globe race.
Ms White said the five crew members would be "looking out for each other".
The Foreign and Commonwealth Office (FCO) has said Mr Smith and his crew - Luke Porter, David Bloomer, Oliver Young and Sam Usher - may have "strayed inadvertently into Iranian waters".
Ms White said she had also known Mr Porter for about three years and the "younger guys" had also "been around for a while" on the yachting scene.
"As far as I'm concerned, they were overly-qualified for this trip, and this should have been something routine for them," she said.
"These guys are my friends, I'm sure everything is being done by the FCO, by the government, to try and make sure that these guys come back safely.
"They'll be looking after each other, I'm sure of that."
She said Mr Smith, who completed a degree in ocean science and marine navigation at the University of Plymouth, had been "in the industry for many, many years".
"He's a very skilled engineer and a very skilled skipper of race yachts and that's what this was, this was a race yacht," she added.
An Iranian official has said "serious" measures would be taken against the crew if it is proved they had had "evil intentions".
Their Team Pindar-backed yacht, Kingdom of Bahrain, was sailing from Bahrain to Dubai to prepare for a race when they were detained.
Dubai-Muscat Offshore Race organisers said the crew may have been "drifting" after experiencing propeller problems.