Passenger ship shake-up

There are more rules and regulations governing passenger ships due to come into force during the next three years than ever before. “More importantly, some of these rules are risk-based rules, not prescriptive any more,” says Markku Kanerva, marketing manager at Deltamarin. Simulation and optimisation tools have been developed to serve as test beds for the new rules and to facilitate design of new ship concepts and configurations. Both fire and safety damage are being revised, which is leading to novel new compartment design on passenger ships.

Kanerva explains that this is the first time the industry has taken a major leap from prescriptive rules towards risk-based rules. This is happening in both fire safety and survivability. SOLAS regulation II-2/17 defines alternative design for fire safety and arrangements and entered into force on July 1st, 2002 and probabilistic damage stability rules for passenger vessels are expected to come into force in 2006. “These two are probably the most important and far-reaching new rules together with the Formal Safety Assessment methodology,” says Kanerva. He told The Motor Ship that in the case of the probabilistic damage approach the method had already been developed “what is missing is the regulations.” Other new rules include Evacuation Analysis, revision of Intact Stability Code, Marpol Annex VI, Safety of Large Passenger ships and so on. Some of these new rules will be retroactive thus affecting the existing fleets as well.

Non-standard

watertight

compartmentation

The new probabilistic damage stability rules are based on a new harmonised survivability index that considers flooding and accumulation of sea water at continuous deck spaces such as roro spaces above damaged waterline as well as single and multiple damages with maximum penetration to the centreline of the ship. The survivability criteria are based on the residual stability characteristics with accumulated water on deck. The final required index is not yet decided, but the work in the EU project HARDER gives a good idea of what is to come.

“All the artificial limits, such as B/5 longitudinal bulkheads, B/10 deck height, margin line criteria and similar will disappear,” says Kanerva. “Compartmentation is no more limited to transverse bulkheads only, and position of bulkheads is not predetermined, except for the collision bulkhead. Transverse, longitudinal and horizontal

compartmentation

is possible and combination as well.”

In ferries, roro decks can be optimised with an efficient combination of lower hold, main deck configuration, casing arrangement and main deck height without affecting cargo capacity, main dimensions of the vessel, weight or building costs. “Real efficiency of lower hold, main deck location, i.e. free board deck height and casing arrangement can be studied together with building costs and survivability, says Kanerva, “it is no more a matter of opinion.”

Alternative design

SOLAS regulation II-2 Chapter 17 enables designers to carry out alternative design and to create alternative arrangements concerning fire safety. This applies for systems, arrangements and complete designs. The requirement is to prove the safety level of the alternative design to be equal to that based on prescriptive rules. Safety level will be defined and proven by engineering analysis including fire technical approach, fire simulations and evacuation simulations.

The alternative design approach allows large passenger, service and machinery spaces beyond what is possible with the prescriptive rules. New constructions and new materials are also feasible.

Larger spaces can extend longer than 48 meters, several decks and their combination. Typical spaces are restaurants, show lounges, activity lounges, exhibition spaces, multipurpose spaces, promenades, atriums, shopping centres, theme parks and similar passenger spaces. Some of the machinery and service spaces may also benefit from the alternative design approach, as functional optimisation is no longer limited to the fire

compartmentation

. Redundancy can also be built more easily with space arrangements. “We may end up with large horizontal and/or vertical machinery and service spaces,” says Kanerva.

Alternative design

offers the possibility to use alternative lighter materials to reach weight savings, reduction of vertical centre of gravity and thus more capacity into limited main dimensions.

“New constructions would allow us to leave out secondary, unnecessary steel structures, use aluminium and composite modular constructions, reduce weight and space and allow higher degree of prefabrication,” he explains.

To be able to carry out the alternative design approach for large spaces in accordance with the IMO/MSC/Circ. 1002 Guidelines requires efficient tools for fire technical analysis and evacuation simulations. What is meant by efficient is that it is suitable for the preliminary project stage as decisions for space allocations and sizes are typically made at the very beginning of the project. “It must be possible to work with preliminary type of information, such as with a rough arrangement and the whole process must be carried out in a few days only, says Kanerva. Handling of alternative arrangement and variations must be even easier and quicker.

An efficient tool must be capable of simulating heat distribution and the spread of smoke and heat distribution into and in structures and to calculate necessary flow rates. It must be also possible to study the effect of smoke and heat detectors, smoke extraction and sprinkler systems and to handle operational procedures.

“Evacuation simulations must be realistic within all spaces and possible crew involvement must be available, explains Kanerva.

Deltamarin has already been using some of these new design approaches in the latest newbuilding for Color Line and told The Motor Ship that the company will be involved in a major cruise ship conversion project early next year if the owner decides to go ahead and “not one of the old ladies,” says Kanerva.

Super Panamax cruise ship

The methods and tools have been used to develop an innovative passenger cruise ship design with the objective of improving the capacity and commercial efficiency of a typical Panamax-size cruise vessel into a Super Panamax vessel. The following new innovative features are being introduced:

l Machinery is located into a new position in the aft ship;

l All services, preparation and storerooms, are relocated in an open large lower hold on the second deck;

l Third deck is released for passenger cabins and necessary tendering and intakes;

l Applying a foldable bow visor the vessel is lengthened by 11 metres;

l Lengthened vessel can carry one additional deck and by using alternative constructions and aluminium in the upper structures, stability of 15 deck high Panamax vessel is managed;

l Large public spaces are introduced to take care of increased number of passengers.

By locating the power plant aft, close to the biggest consumers ? the pod propulsion motors, the whole midship area is released for other purposes. “The idea is to have all machinery functions located aft, remove all service, preparation and store spaces to a dedicated area on deck 1, getting rid of all the disturbing flows, which typically appear on the third deck, such as passenger tendering and luggage handling,” says Kanerva. More efficient flows and better use of space becomes possible with the totally separate arrangements. It is estimated that 5.000 m3 to 8.000 m3 of valuable space can be released into revenue generating spaces. “The probabilistic damage stability approach allows us to proceed with this type of arrangement and actually survivability of the design becomes better than with a conventional Panamax design of today,” he explains.

Bow visor alternative

A foldable bow or bow visor is well known in roro passenger ferries, but not yet applied in passenger cruise ships. In an innovative design twist, Deltamarin is proposing using an eleven metres long bow visor, which can be turned into its upper position when passing Panama Canal, thus reducing the canal passage length, to build an eleven metres longer cruise ship.

Deltamarin has already had the Panama Canal authority look over the design and it has given its approval provided there is adequate visibility. This longer length gives more additional displacement than what is needed for the additional weight and deadweight of another full cabin deck “if we just can meet the stability requirements,” says Kanerva. He explains that the fifteenth deck can be added by using alternative design approach to reduce the amount of non-structural secondary steel bulkheads with lighter constructions and materials with equivalent fire safety. Aluminium would be needed for the uppermost full deck as well.

Kanerva told The Motor Ship that the aluminium deck, or a little more than one deck, would be required to lower the centre of gravity to avoid making the hull form more bulky and more barge-like, which would not be seaworthy.

He explains that the reason behind saying “a little more than one deck”, is that a building yard might come to a slightly different conclusion when carrying out its own weight calculations.

Although the design is not new ? Cunard explored the possibility up to ten years ago ? Kanerva told The Motor Ship that there had been renewed interest in the concept, particularly with one very interested owner.

The Super Panamax design is created with 1340 passenger cabins, which an increase of 290 cabins. Crew and public spaces are also increased accordingly to guarantee the required service standard and space per passenger. The following table presents the main characteristics of this new Super Panamax design in comparison with a typical Panamax cruise ship of today.