Cruise lines are investing heavily in upgrading existing ships, to keep up with commercial, environmental, and safety requirements. Commercial concerns favour increasing ship capacity, but this can mean increasingly complex work that must be carried out during dry-dockings.

By Kari Reinikainen

Highlighting the trend, companies such as Holland America Line, MSC Cruises, and Azamara all recently unveiled major projects to upgrade some or all of their existing vessels. Upgrades of cruise ships focus mainly on three areas: improving the guest experience, enhancing the ship’s environmental performance, and improving operational efficiency.

That’s according to Michele Landro, vice president, head of passenger ships segment North America at RINA. “The real challenge of a major refit is that every visible change has a hidden technical impact across the vessel,” he said.

This is because a ship is an integrated system of systems. Changing one parameter makes it necessary to review the potential effects across the vessel. Say for example that a new accommodation block is added on the upper decks, or new cabins are built in an area previously used as a public space. This would mean that stability, structural strength, fire safety, HVAC, wastewater, power supply, and other onboard systems all need to be assessed.

Complexity of retrofits

Ships differ greatly when it comes to how easy or hard it is to carry out major modifications. Some vessels, particularly more recent ones, may have sufficient stability margins and technical flexibility to allow such work to be carried out more easily. Others can be much more challenging in this respect, and Landro said it is essential to start planning early: “Ideally, the planning should start at least 12 months before the ship is scheduled to enter dry-dock.”

The significant growth in cruise ship size over the years has made dry-dock and retrofit work more complex. Further complexity arises, Landro said, when a vessel is sold to a new owner who wants to transform the interiors to meet a new brand identity. The effects are not just cosmetic but also structural.

“In this context, familiarity with the realities and constraints involved, whether on the cruise line owner side or within a third-party ship manager, is particularly valuable,” he said. But it is not always possible to carry out the owner’s plans exactly as initially intended, because of vessel-specific limitations. Landro added that RINA supports owners with consulting and engineering services during the planning and feasibility phases. It is helped in this capacity by the expertise of Foreship, a Finnish company that it recently acquired.

A clear trend is emerging in work on second-hand vessels. New owners investing major capital in the acquisition and retrofit of a ship increasingly want to understand how it can remain aligned with known and emerging environmental requirements, including IMO decarbonisation targets, Landro said.

Careful planning

Paul Nichols, from the Cruise Ship Centre of Expertise at Lloyd’s Register, says the first consideration should be whether the proposed modification counts as a “modification of a major character” under SOLAS. According to SOLAS, repairs, alterations, and modifications of a major character, along with their related outfitting, must comply with requirements for ships constructed on or after the date on which any relevant amendments enter into force, to the extent deemed reasonable and practicable by the flag state administration.

In the case of major modification, the altered part must comply with current rules, not those that apply from the original build, again as far as the vessel’s flag state deems sensible. “Most modifications will not require this approach, but that should be a formal decision by the regulators and not a ‘We didn’t think it applied’ statement by a designer,” Nichols told CruiseTimes. “If a lengthening was planned as a major modification, the new section should meet current requirements, not the original, where relevant. This decision establishes how regulations will apply.

“For many years, ships have been designed using direct calculation or a finite element model (FEM), rather than prescriptive structural rules,” he said. “These create an optimised structure where stresses and strains are considered and dealt with appropriately. When modifying a structure, the same process should be applied to prevent overload. In the past, if the original FEM is unavailable, Lloyd’s Register has recreated part of the FEM then applied the modifications to accurately predict structural reactions.”

Adding more structures to the hull is likely to increase the enclosed volume, so the tonnage calculations must be updated, including the inclusion of additional passenger numbers in the tonnage certificate. “Depending upon the flag state of the vessel, this may result in the requirement for a new carving and marking note to be issued by the flag authority,” Nichols said.

Increasing a vessel’s side profile can affect the equipment numeral, which determines the size of anchors, chains, and mooring equipment. Whether this applies depends on the ship’s original arrangements and the geometry of any additions.

When adding passenger cabins or public spaces, consider the following:

Because there are more people, Lloyd’s Register needs to verify that staircase and corridor sizes are still suitable as escape routes, per the 2020 amendments to SOLAS.
Escape signage must be provided, including low location lighting and specific cabin placards.
More cabins and passengers means that more life-saving appliances are needed, including lifejackets and group equipment such as lifeboats. It’s important to maintain the right balance between lifeboats and liferafts, so these numbers need verification. Muster station areas need reviewing to accommodate the extra people.
Construction materials should be evaluated for combustibility, low flame spread, and ability to generate smoke and toxic products. They should be Fire Test Procedure Code certified. New fire load calculations should be considered where appropriate.
Structural fire protection of the boundaries of any new spaces needs to be considered – for example, if a ceiling needs extra insulation, this may affect requirements for the deck above it.
Additional electrical load for lighting, including emergency and supplementary lighting, may require a new load balance and testing of the emergency battery.
Ventilation systems will need modification, and care should be taken on duct routing. For example, staircases should have dedicated systems, and not a spur from an accommodation area.
Fire extinguishing systems may need to be added or changed, and the sprinkler system reviewed. Include these changes in the ship’s fire control plan and training documentation.
Fire detection systems will be needed in new cabins and corridors, including manual call points. The fire patrol route may need to be modified.
Public address and general alarm systems may need upgrading to cover additional areas. Amplifiers and power supplies for these systems should be reviewed on the space’s sound levels.
Extra fire doors may need to be installed, and some may require bridge control. Door indication and control would need integration into the safety management system.
The impact on the ship’s piping systems will need to be assessed, resulting in changes to the fresh-water, grey-water, and black-water systems.

Stability rules

Ships naturally grow heavier as they age, because of new equipment, new systems, and even regular repainting. Significant modifications can make an even bigger difference in stability.

Controlling weight is important, as exceeding a 2% increase in lightweight or a 1% change in longitudinal centre of gravity automatically triggers a requirement for an inclining test. “Passenger ships have their lightweight verified every five years, but after significant modifications, it would be advisable to make a lightweight check or plan an inclining if getting close to these limits,” Nichols said.

Safe Return to Port rules that apply to passenger ships more than 120 m long or with more than three fire zones built after 1 July 2010 add their own complexity, and their applicability is well documented in the ship’s records. “The rules aren’t very prescriptive, and solutions used on two similar sized ships could be quite different. This means anyone looking to modify the vessel must be aware of the solutions used on that particular ship,” Nichols said.

Many newer ships use alternative design and arrangements (AD&A), often featuring elements such as extra-large main fire zones and oversize lifeboats. “To uphold safety standards set by the prescriptive rules, these AD&As employ equally safe alternative solutions,” said Nichols. “Designers must carefully assess how any proposed modifications might affect applied AD&As to ensure acceptable arrangements.”

Keeping records

Finally, it is important to adequately update the vessel’s records – something that is easy to forget. Nichols thinks the best way to think of this is to imagine having to do the same job in the future. “If you’d then think, I wish I’d kept that, when reviewing your current documentation, make sure to record it now,” he advised.

Some ships, by virtue of their design, are more suited to modifications, said Almaco, the Finnish turnkey contractor for hospitality and interior areas on board ships and offshore installations. “Vessels with modular construction and clear technical documentation are typically more adaptable to major changes...

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