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DescriptionUniqueness of the CalMac Fleet - A summary paper
Official Print Publication Date
Website Publication DateOctober 04, 2005


A paper prepared by the Economic Advice and Statistics Division of the Scottish Executive Development Department in June 2001 on the basis of work carried out by Saltire Management Limited (Marine and Operations Consultancy)




Closed Car Decked Ro-Ro Ferries

Open Decked Ro-Ro Ferry

Alternative Delivery Options for Dangerous Goods

Double Ended Open Deck Ro-Ro Ferry

Side/Rear Loading Ferry

The Carriage of Livestock

The Cascade of Interchangeability

Shore Facilities

Alternative Tonnage

The Second Hand Market



A paper prepared by the Economic Advice and Statistics Division of the Scottish Executive Development Department in June 2001 on the basis of work carried out by Saltire Management Limited (Marine and Operations Consultancy).

Scottish Executive Enterprise, Transport and Lifelong Learning Department: September 2005


This paper was prepared in 2001 for the Maritime Transport Division of the Scottish Executive (which was then located in the Scottish Executive Development Department) by that Department's Economic Advice and Statistics Division on the basis of a research report prepared by Saltire Management Limited (Marine and Operations Consultancy). The paper was prepared as part of the development of the Executive's proposals for the tendering of the Clyde and Hebrides ferry services and fed into the Executive's consideration of the case for tendering the Clyde and Hebrides network as a single unit. The paper was not prepared with publication in mind. However, in the light of recent interest in this subject, the paper is now being published through the Scottish Executive website and by lodging it in the Scottish Parliament Information Centre.

Scottish Executive Enterprise, Transport and Lifelong Learning Department

Maritime Transport Division

September 2005


1. The purpose of this paper is to examine the extent to which the existing Caledonian MacBrayne fleet can be said to be uniquely fit for purpose.

2. The fleet of vessels that Caledonian MacBrayne use to serve the Western Isles of Scotland is made up of 27 vessels serving 39 routes and can usefully be split into four principal designs of ship. These are as follows:

- The "Closed Car Deck" RO - RO Ferry (3 vessels)

- The Major "Open Car Deck" RO - RO Ferry (5 vessels)

- The "Double Ended" Open Deck RO - RO Ferry (15 vessels)

- The "Side / Rear" loading Ferry (4 vessels)

The paper will deal with each of these classes of vessel in turn.

Closed Car Deck RO - RO Ferries

3. Caledonian MacBrayne operate both "open" and "closed" deck RO - RO ferries. The "closed" deck ferries are similar to car ferries around the world. They have bow and stern doors and a fully enclosed car deck. The vessels built for CalMac however are built to a specific set of dimensions allowing a maximum length of 100 metres, a maximum beam of 15.8 metres and 3.2 metres maximum draught. These dimensions have been chosen in order to allow the company the flexibility to deploy any of these vessels to any port in the network. Blasting the bedrock or dredging could increase the depths of the berths at the ports, but this would be expensive and once the new depths had been achieved they would require regular dredging in order to be kept clear.

4. Vessels of the size of Caledonian MacBrayne's closed deck RO - RO ferries would normally be built with a draft of around 5 metres as the 3.2 metre draft limit results in vessels that are relatively expensive to run in terms of fuel efficiency. This increased fuel cost reduces the likelihood that other operators would have built vessels to similar dimensions. The routes, on which Caledonian MacBrayne operate however, are characterised by shallow ports, where the depth of water at the ferry berth is frequently less than 4 metres. A vessel with a nominal draft of 5 metres could operate from the same ports as the Caledonian MacBrayne vessels providing it was not fully loaded. This would however be a very inefficient way to operate.

5. On the Ullapool to Stornoway route Caledonian MacBrayne operate the MV Isle of Lewis. This vessel is unique within the major units of the CalMac fleet in that she has a draught in excess of 3.2 metres, a length in excess of 100 metres and a beam of more than 15.8 metres. She cannot operate elsewhere on the network other than on the Ullapool - Stornoway route. The vessel has been constructed to these dimensions because the route on which she operates is less restricted than for the other vessels, with a minimum depth of 7 metres. As it is common policy to allow clearance under such large vessels of one metre the route could be operated by any vessel with a draft of up to 6metres.

6. It is necessary to carry certain goods such as petroleum spirit, fertilisers and whisky to and from the Islands. The transport of these goods has to be carried out in accordance with the requirements of the IMDG code. The code classifies dangerous goods according to type and stowage requirements. Restrictions are placed on the categories and mix of goods that may be carried by passenger ships and the numbers of passengers who may be accommodated at the same time. It is an international regulatory requirement that some of these goods be carried on the open deck rather than in an enclosed car deck. As the Islanders are reliant on the import and export of traffic covered by these regulations it has been necessary to adapt the service to allow their carriage. The result has been a unique hybrid, the major "open decked RO - RO ferry". These vessels are able to carry a mix of passengers and dangerous goods that would be impossible on the closed deck vessels of the fleet.

Open Decked RO - RO ferry

7. The open decked RO - RO vessels operated by Caledonian MacBrayne are limited to the same maximum dimensions as the closed deck vessels for the same reasons. They are however unable to accommodate the same number of passengers as the passenger accommodation is curtailed by the constructional restraints imposed by the requirement to leave the car deck open.

8. The open car deck prevents the possibility of dangerous gases building up on the vessel. This has allowed these vessels to be granted an exemption, by the MCA, from the regulations restricting the number of passengers carried and allows them to operate an economic service while carrying restricted substances. It is a condition of this exemption that no suitable cargo service exists. If a freight service was introduced on these routes it is likely that this exemption would be withdrawn. In that case a more "traditional" RO - RO ferry could operate the routes providing it has a shallow enough draft. It is however, unlikely that a vessel could in any case be found with a draught of 3.2 metres or less.

Alternative Delivery options for Dangerous Goods

9. If an alternative freight service could be operated to the Islands it might prove possible to replace the "open decked" Ro - Ro's with closed deck vessels (albeit still limited to the same maximum dimensions). With this in mind an independent shipping consultant studied the practicality of operating either a single freight vessel on a circuit of the Islands or a freight only sailing by the regular passenger vessel once or twice a week.

10. From a purely logistical point of view it would be possible to operate a freight service that served all of the Islands over the course of a week. However, the consultant identified difficulties with this approach. When dangerous goods are carried in road vehicles on ferries it is a requirement that the driver of the vehicle travels with the load. This is because the driver is trained in the appropriate emergency procedures for his cargo. Some loads are however considered to be at least as dangerous when returning as when travelling out. By way of example both petrol tankers and bottled gas are considered dangerous when empty. This means that these vehicles and their drivers would not be able to return on the next scheduled sailing of a closed deck vessel but would have to wait for a week on the Island for the return of the freight ship. This is clearly uneconomic.

11. The second alternative examined related to the scheduled vessel operating one or two dedicated freight sailings per week. It was felt that if these sailings were identified clearly on the timetable there should not be too great an impact on passenger traffic as customers could adjust the timing of their journeys to avoid them. However, problems were identified with this approach. The first problem is that certain types of dangerous goods may not be carried on the same vessel at the same time. For example, petrol and butane may not be carried together. If there was only one sailing per week then cargoes might be unacceptably delayed. The obvious solution is to operate more than one freight sailing per week. Unfortunately, this is not practicable on many of the routes where the number of passenger sailings is already limited and this would impose too great a restriction on travel.

12. The use of "open decked" vessels allows the carriage of both freight and passengers to the Islands in a timely and safe manner. It appears to represent the most efficient way of providing the dangerous goods that the Island communities rely on.

Double Ended Open Deck RO - RO ferry

13. Caledonian MacBrayne makes extensive use of double ended open decked RO - RO ferries. These vessels operate off inclined concrete slips on short sheltered crossings. The vessels are of specialised design, as the hull form has to be designed such that the propulsion units are not damaged when the vessel berths on the ramp. Though these vessels could be adapted to operate off linkspans it would be very difficult to convert vessels that operate off linkspans to operate off the slips. There are other ferries of this type operating in UK waters as well as some in Norway, Sweden and Holland. While these vessels may be adaptable to suit some of the Caledonian MacBrayne routes it is unlikely in practice that they would be available.

Side / Rear Loading Ferry

14. Caledonian MacBrayne currently own and operate four vessels with side and stern rather than bow and stern doors (additionally the MVs Hebridean Isles and Lord of the Isles also have side doors in addition to their bow and stern doors). These vessels operate on the Gourock - Dunoon and Wemyss Bay - Rothesay routes. At Wemyss Bay and Gourock these vessels are loaded and unloaded via their stern doors as with other ferries. At Dunoon and Rothesay the vessels are loaded unloaded via their side doors. This is as a consequence of the construction of the berths at Dunoon and Rothesay, which cannot accommodate end on loading because the ramps are built at right angles to the face of the piers and there is no method of securing the ship end on. It would be unlikely to find similar shallow draft vessels with a combined side / end loading configuration operating elsewhere.

The carriage of Livestock

15. The economies of the islands served by Caledonian MacBrayne are dependent to a significant degree upon the agricultural sector. The Islanders rely upon CalMac to transport their livestock to and from the Islands. Livestock is carried to and from the Islands on multi tiered floats. Two and three tier floats are considered suitable for carriage on Ro - Ros providing that ventilation is adequate (up to 5 livestock vehicles, 10 air changes per hour). It is economically advantageous to transport livestock in the highest tiered vehicle possible and for this reason hauliers would prefer to use three tiered vehicles when ever possible. More efficient haulage has implications for the cost per head of shipping livestock and could potentially have an effect on the profitability of the producer.

16. Three tiered floats may only be carried by closed deck Ro - Ro ferries when the dockside temperature is below 20 degrees Celsius. On average, this temperature is exceeded in the West Coast of Scotland less than 50% of the year. On those days however, the existence of an open decked vessel allows the carriage of vehicles that would be prohibited on a closed deck ship.

The cascade and interchangeability

17. As the vessels in the fleet come to the end of their useful lives their capacity and performance have usually become insufficient for the route on which they serve. Usually, the fleet will require the replacement vessel to be the largest size that can be accommodated at all the ports in the network. The new vessel is added to the network at the point shown to be most in need of new capacity. The rest of the fleet may then be cascaded downwards as appropriate, so that multiple routes may benefit. If this process is to happen then new vessels are limited in size so that they themselves can eventually be cascaded down in the future. Such cascading is obviously limited to vessels within a given class. A large closed deck ferry cannot, as mentioned in paragraph thirteen above, operate off a slip.

18. Similarly, this ability to cascade is useful whenever a vessel breaks down or alternatively has to be dry docked for the renewal of her passenger safety certificate, as it allows the relief vessel to operate on any route (subject to the caveat in 15 above).

Shore Facilities

19. The linkspans that are in service at the ports on the network effectively limit the beam of ships using them to 15.8 metres at the present time. The use of a fender may permit narrower vessels to use the linkspan but if wider vessels were to be used then the linkspans would require modification. As discussed at 14 above the linkspans at Dunoon and Rothesay are only suitable for vessels with side ramps.

Alternative tonnage

20. Ferries, which are completely specialised, are normally built against specific routes. A fleet owner will normally take the decision to order a new vessel because an existing vessel has reached the end of its' working life or is going to prove too costly to upgrade to satisfy new safety legislation.

21. New vessels built as a result of the above scenarios will be designed with the aim of best serving the route on which they will be employed. It is normally expected that when a vessel is ordered for a route she will see out her working life on that route. The overall effect is that there is no ready supply of new tonnage or tonnage under construction, which is uncommitted, from which replacements for the larger Caledonian MacBrayne vessels could be found. The unusual draft and beam restrictions necessary for ships to operate on these routes further restrict the potential availability of second hand vessels from the external market This restriction also applies to the medium sized vessels in the fleet.

22. The smallest vessels in the Caledonian MacBrayne fleet are not, as was pointed out in 13 above, unique. They are specialised, in that they have particular features of underwater design that match them to the routes they serve. Because there is a relatively restricted market for these vessels it is considered unlikely that craft would be available, either under construction or available new. It should be pointed out that these vessels are not particularly complicated from a technical point of view, and newbuild vessels could be ordered to replace any of them.

The Second Hand Market

23. The legislation governing the levels of safety required by RO - RO ferries at sea has been tightened in recent years as a result of the sinking of first "Herald of Free Enterprise" and then "Estonia". Vessels that were trading at the time the legislation was introduced were allowed time to comply. Some ships were physically unable to comply with the regulations as a result of their design and others were simply not economic to upgrade. This has resulted in the phasing out of older non-compliant tonnage. These older vessels have had to either be scrapped or sold on into markets where the regulations are not in force. This in turn means that there is virtually no supply of second hand vessels that comply with current safety legislation. This situation was exemplified by the inability of groups tendering for the recent Northern Isles ferry contract to identify suitable second hand tonnage. In the end the winning group (Northlink) had to order three new vessels from the Aker-Finn shipbuilders in Finland.

24. This market situation has to be examined in conjunction with the particular features of the Caledonian MacBrayne vessels. These include, the requirement on some routes for "open decked" vessels in order that dangerous cargo may be carried, the shallow drafts required on nearly all of the routes, the capability of the slipway operated vessels and the requirement for the upper Clyde vessels to load and discharge over both the stern and side. This set of requirements and circumstances makes the probable total supply of alternative tonnage almost nil.

25. The Ullapool - Stornoway route is different in that, as a result of the greater depth of water, it is likely that an alternative vessel could be found to operate the route.


26. The fleet as it currently stands appears to have evolved into the best mix of vessels to meet the requirements of the varying routes. It is almost impossible to believe that there would be a similar fleet anywhere, which contained the correct mix of vessels, of the correct types and of the required dimensions, in respect of draft, beam and overall length. Some of the vessels possess unusual features such as, side ramps and open car decks and it is even harder to see from where alternatives to them could be sourced, given the nature of the cargoes they are required to carry. To this extent it can be said that the fleet is uniquely fit for purpose. However, a conventional 5 metre plus draught vessel could serve the Ullapool - Stornoway route without having compromise its efficiency by running with a reduced load, due to the depth of water available in the harbour.

Scottish Executive Development Department

Economic Advice and Statistics, June 2001