A lot of people in Orkney have been learning about crankshafts this week, and a few in the Scottish Government as well.

Most of them know it is the part of an engine that translates reciprocating linear piston motion into rotation. But in the case of the crankshaft in the starboard engine on the ferry Hamnavoe, it stopped translating on Thursday of last week. As a result the SercoNorthLink’s lifeline ferry service from Scrabster in Caithness to Stromness in Orkney has been withdrawn ever since.

The Hamnavoe limped down to Rosyth on its port engine earlier this week and a crankshaft from Germany is to be installed at the Fife port; the vessel is not likely to be back till May 24. That will be right in the middle of the all-important Orkney Folk Festival, which is expected to draw 2000 visitors to Stromness, who will spend up to half a million pounds over the four days.

Many islanders have been wondering where exactly Serco NorthLink’s plan B has been.

The controversial multinational, which specialises in managing outsourced government contracts here and abroad, won  the new £243m six-year Northern Isles ferry contract in May last year. It took over from the publicly owned NorthLink Ferries, part of the David MacBrayne Group which includes CalMac , although the vessels are owned by a subsidiary of the Royal Bank of Scotland - that’s another story.

But people on Orkney remember those days and how when the Hamnavoe had to go off before, a ferry from the CalMac network  would head north to take over. That’s not going  to happen this time. So unless efforts by  Serco and the publicly owned Caledonian Maritime Assets Ltd (CMAL), which holds CalMac’s  fleet and has been ordered to help,  prove fruitful and a short-term replacement vessel is found  in Europe, Orkney will have to make do with what it's got .

What it's got is  a Pentland Ferries catamaran car ferry from Gills Bay to South Ronaldsay, Serco’s thrice weekly service to Aberdeen from Kirkwall, the John O’Groats to Burwick passenger-only ferry which has just started for the season, and the temporary freight service introduced by Serco this week on the Scrabster to Stromness line. But while this can carry lorries and - technically - cars, it can only manage 12 passengers or drivers.

The 20,200 islanders won’t be cut off by any stretch of the imagination but they will be seriously disadvantaged by the loss of the Hamnavoe on the Scrabster to Stromness run. It wasn’t classed a lifeline service for nothing and as it provides almost 60% of the car carrying capacity on the Pentland Firth, there is an obvious impact on the vital tourism business.

Obviously it would have been worse if it was an island which had lost its sole ferry service to the mainland without any road access to another – say Islay, Coll,  Tiree or Colonsay, never mind the shorter crossings to the likes of Iona, Raasay, Lismore.

But the question of who should step in during such circumstances is one that has exercised many in the neverending debate over whether CalMac’s network should be broken up to allow private operators take over the busier routes – the so-called cherry pickers. What would happen if their vessel broke down?

The Scottish Government’s decision last year not to tender CalMac’s routes until  autumn 2014 and, crucially, that firms will be invited to submit bids for the 24 routes as a single contract, reduces the chance of the Orkney experience being repeated. There is normally a back-up vessel which can be used in the CalMac network.

But the cherry pickers will return, and are unlikely to have developed a plan B in the event of their crankshafts going. It is worth remembering that tireless ferries campaigner Professor Neil Kay has been raising this issue for well over a decade.

He did so again in May 2008 in supplementary written evidence to the Scottish Parliament’s Transport, Infrastructure and Climate Change Committee for its Ferries Inquiry. He addressed the need for a recognised “operator of last resort” to stand in when something goes wrong.

He warned that “you cannot wait until the incumbent operator fails before trying finding an operator of last resort. Such an operator of last resort has to be able to be directed and contractually obligated to take over immediately in providing essential services in the event of an operator failure for whatever reason.”

He said that representatives of private interests (would-be cherry pickers) had said in their evidence to the committee that the state/CalMac should be the operator of last resort. That would be difficult, he said: “Unfortunately, if what is meant by CalMac is CalMac Ferries, CalMac Ferries is only one of potentially many operators (which just happens to be state owned). They cannot be discriminated for or against under EC law, and indeed CalMac ferries (and its holding company David MacBrayne) has no guaranteed existence, status or function as an operator beyond the time horizon of a six-year Public Service Contract. You cannot solve the problem by assigning a role in perpetuity to an entity with a finite and uncertain existence under EC law.

“The only way you could safely assign that role to CalMac would be if you were prepared to fix things so that it would always win its present contract and network tender - which of course would certainly breach EC State aid rules...”.

Making CMAL the operator of last resort wasn’t a last resort either, as it “would not have the appropriate experience or certificates.” He concluded that the problems facing Scotland’s ferry industry are "systemic, and the solutions must be systemic.”

But nobody has found a solution yet  for Orkney.