But together, aboard the MS Aquarius, they get the job done. Since it joined the international search and rescue operation off Libya in February, the boat chartered by medical charity MSF and French NGO SOS Mediterranee has safely delivered some 1,500 migrants to Italian ports.
Once the property of the German coastguard, the Aquarius switched to oil prospection in 2009, surveying prospective fields from Nigeria to the Arctic.
Now it is stuffed full of life jackets, blankets, nutrition packs and bottles of water.
On the deck, SOS Mediterranee volunteers rotate the watch. Several of them are merchant seamen themselves, a mix of keen youngsters and salty old sea dogs. Most have given up three to six weeks of holiday time to help out.
"Working only for yourself is not necessarily what makes you proud in this life," said one of them, 25-year-old merchant seaman Antoine Laurent.
'A unique experience'
Down several narrow flights of steps, the MSF medical team - a doctor, midwife, two nurses and two technicians - prepare to take charge of rescued migrants who will be spending anything from a few hours to several days on board.
Unlike the SOS Mediterannee crew, most of them had never set foot on a boat before but can call on vast reserves of experience acquired in humanitarian hotspots from the Ebola clinics of West Africa to the earthquake-ravaged mountains of Nepal.
Dutch doctor Erna Rijnierse, who has been working with MSF for a decade, describes the work on the boat as a one-off.
"I've been involved in long term projects, I've been involved in emergencies... This, however, is very unique.
"There are elements of different MSF missions but the fact that you do this on water, with people in flight that have been travelling already quite a bit, and on the doorstep of Europe, makes it very unique."
What is notable aboard the Aquarius is the commitment of the boat's permanent crew - a motley collection of taciturn Russians and Ukrainians, several Ghanians and a worrisome Greek. None of them chose the mission but all them have thrown their hearts into it.
Going to the aid of stricken boats is a moral and legal obligation at sea but picking up migrants represents a headache for merchant ships with deliveries and collections to be made, and fears of infection by sick shipwreck survivors abound.
But it is the veteran seamen who have the skills required. Aquarius seaman Ebenezer Tandot, 45, has long worked around North Sea oil platforms, where hypothermia can claim even the strongest swimmers in as little as eight minutes.
'Doing something good'
So it is the Ghanaian who is tasked with guiding the first lifeboat to be launched.
"We pick up the migrants, we drop them off, it has become the routine," he tells AFP.
But his nonchalant tone changes quickly as he emotionally recalls the impact of rescuing men in a state of shock or paralysed by hypothermia and the relief at seeing them begin to come round and recover.
Such emotions help to explain how the crew has bonded, despite their vastly different backgrounds. "We actually feel like one big team trying to take the best care we can of the people we have rescued," says the MSF doctor.
The boat's skipper is Alexander Moroz, a 45-year-old Belarusian with a dry sense of humour. He is the point man who receives instructions from Italy's coastguard and directs operations.
The work has nothing in common with his boat's past. "But my feeling is I am in the right place and that I am doing something good."
Asked if the presence of rescue boats is only encouraging people traffickers to send their human cargoes to sea, the skipper adopts the same line as the humanitarian contingent on board.
"The only question is, if we were not here, how many more would die?"