LETTERS | Unconsidered costs of much-delayed CalMac ferries

The CalMac Ro-Pax ferry Glen Sannox. As of November 2022, the vessel remains unfinished nearly five years after it first took to the water. (Photo: Ferguson Marine)

I have read the above article which I consider “game, set and match” as far as truth, depth and accuracy of cover. It does however “ring the Lutine Bell” as far as delivery of anticipated service.

The financial disaster experienced so far is small change when compared to the costs of putting these vessels into service and maintaining them for any length of anticipated service life.

No one wants to look over the hill to even consider potential events.

Given that most vessels will have an anticipated 12- to 18-month build period, equipment delivery and systems preservation/activation are programmed for minimal site exposure to preserve reliability for trials and service.

Given the lengthy period (years) systems and equipment have lain exposed to the Scottish climate, it is doubtful the vessels will ever make acceptance delivery.

Of main concern will be:

  1. The breakdown of internal coating minimal DFT’s especially at the welds and hard edges, both of which promote corrosion due to galvanic action of hardened surfaces of welds against the less anodic steels (usually about 0.2 to 0.4mm/year).
  2. More significantly will be the development of MAC (microbial assisted corrosion) within internal spaces, especially partially ballasted or moisture coated surfaces with light contamination of river water oils, which have lain undisturbed for months. I have experienced full penetration of 12mm stringer decks under such conditions within a 12-month period.
  3. Machinery never rotated over a long period will suffer from micro welding of contact points (such as bearings, both bush and ball) due to transient currents from ongoing welding (despite hull earthing straps).
  4. Main and auxiliary engine liners/pistons/bearings/crankshafts have preservation fluids applied but these do not usually last more than six months before breakdown, resulting in corrosion and need renewal.
  5. Turbo charger rotors, main shafting and general drives etc. require regular rotation to avoid sag and permanent set.
  6. Machinery oil sumps have minimal oil levels added. However when moisture is present (from damp atmosphere), this will promote sulphite reducing bacteria (SRB) resulting in the pitting and corrosion of machined surfaces and chocking of oilways when run. Major replacement and decontamination is the only solution.
  7. The lack of atmospheric control (dehumidifying) has to be in force in all internal spaces from not less than three months out of service (we are now at five years!).
  8. Electrical motors need to be kept warm and dry when out of service for periods (usually low voltage current 24V passed through windings prevents this. Electrical control circuits (PCB’s), as well as needing dehumidifying, need to have surfaces coated with filming amines (such as Zeerust) to avoid contact oxidisation that result in premature failure and fires. This needs application within three to six months of non activation.
  9. General electrical cabling will be subject to widespread earthing and failure due to the lack of atmospheric moisture prevention.
  10. Pipework will be subject to internal corrosion due to lack of use. Freshwater pipework and tank systems will suffer from bacterial infection due to lack of passivation.

The list is endless. The cost in terms of replacement will be astronomical and time projections, months.

Given the high profile of these vessels and their potential failure, flag state and class authorities will be on high alert and well versed in these potentials and well aware of reputation damage to ignore the obvious.

All the above is of course a precursor to getting the vessels “of merchantable quality” and “fit for purpose” to go on yard trials even before handover to owners!

Of course the caveats of “no guarantee”, plus the government-owned yard and shipowner, mean the incurred costs are to “Joey Taxpayer”, and subject to “left pocket to right pocket” accountancy practices.

Nevertheless the Armageddon has not arrived. Yet.


Eur.Ing. Joe Mckee. C.Eng.,C.Mar.Eng.F.I.Mar.EST


Dundee, Scotland

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