The conversion of a private yacht to one for commercial use requires building in higher standards of fire safety. Richard Custer, Matthew Johann and Jeffrey Tubbs explain the different approaches that can be taken.
Maritime codes for passenger ships differentiate between private and commercial (charter) yachts, much like most building codes provide different provisions for family homes compared to commercial buildings. Code provisions for private homes are generally less restrictive than those for commercial occupancies, and this is similarly true for ships.
Fire and life safety components are specified and installed in accordance with the codes that govern the proposed initial use of the vessel. But what happens when the owner of a private vessel decides to place it into commercial service? How can a ship that was not originally designed to conform with commercial yacht codes be upgraded to meet those more intensive provisions?
Numerous codes exist for maritime fire and life safety. For instance, private yachts are frequently built in accordance with the Special Service Craft (SSC) rules published by Lloyd’s Register. But codes for commercial yachts, such as the Maritime and Coastguard Agency’s Large Commercial Yacht Code (LY2) or the International Convention for Safety of Life at Sea’s rules (SOLAS) are different. Specifically, yachts that meet the SSC rules often lack the compartmentation, egress capacity, egress component labelling and crew training demands for yachts in charter service.
Regulations for compartmentation and egress capacity are frequently the most onerous part of a private-to-charter yacht conversion. For many projects, private yachts have open stairs linking the various deck levels, with the potential of smoke and fire spread between decks. Some stairs can open directly onto service, storage, and mechanical spaces, which is specifically disallowed by the LY2. Also, egress paths from some areas of the ship can use common paths of travel, meaning a single fire event could block multiple egress paths.
So the challenges revolve around the need for enhanced compartmentation and escape routes. Barring significant alterations, it can be difficult to add fire rated barriers between existing compartments, or to enclose existing openings in a way that maintains the aesthetics and functionality of the vessel.
Design approaches
Some prescriptive code deficiencies identified in the design of a yacht can be solved through simple alterations that bring the vessel into compliance. Where existing constraints allow, this is the simplest approach for the private-to-charter service transition. But others will need a performance analysis to determine equivalence with the code provisions. SOLAS permits alternative fitting, material, appliance, or apparatus not specifically allowed by prescriptive codes, if it is proven to the authority having jurisdiction that the solution is at least as effective as the provisions of the prescriptive code.
Issues involving lack of compartmentation are often prime candidates for retrofit in order to meet the prescriptive requirements. As an example, consider a yacht with numerous unenclosed stairs. In this case, rated doors with threshold seals could be added to provide the required fire rated separation. This, however, results in functional problems since the openness of the ship and the ease with which passengers can move about are often important to the owner. To accommodate these needs, the stairway enclosure doors can be equipped with magnetic hold-open devices and automatic closers, which release through activation of the fire detection system or through manual controls located on the bridge.
Often in private yachts, fire doors may exist to separate service areas of the vessel from public areas; in a charter yacht these doors also need to be remotely controlled in order to contain fires. The ability of the crew to close these doors in the event of a fire is important in order to help ensure that exit routes not directly affected by a fire will be tenable, and to help limit the overall fire spread. Additionally, all egress components, both new and existing, need to be clearly labelled according to prescriptive code provisions.
The upgrading of a vessel to charter service often introduces new crew emergency training needs, and the design strategy should include recommended crew actions for various possible fire scenarios.
The types of modifications discussed above can bring much of a private yacht into compliance with the commercial codes. However, the egress capacities and arrangements within portions of these ships often do not meet the requirements. These issues frequently cannot practicably be resolved through a prescriptive code compliance strategy. Instead, a ‘code equivalence’ approach may be needed.
Fire engineering
Continuing our example, consider that the guest sleeping quarters (staterooms) of the yacht are all located on the same deck at the aft of the vessel. The suite of staterooms is served by a single stair, with additional exiting provided through two hatches. Such hatches are often located in a ceiling and include a deployable ladder, in order to allow occupants to move to an upper deck in an emergency. Also, hatches in bulkheads can be used to provide an opening between adjacent compartments that would not be open to each other during normal operations (for example, a guest stateroom and crew stairs). Each of these types of hatches requires a certain level of training and/or crew assistance to operate. In our example, one of these hatches is located in a stateroom, the doors to which could potentially be locked by its occupants when a fire occurred. The second hatch essentially leads to the same exit as the stair, and thus a single fire could block both of these means of escape. These issues cannot be solved easily through prescriptive code compliance.
One option for dealing with these deficiencies is to prove that the egress system would in fact provide an acceptable level of fire and life safety. For instance, while the prescriptive codes may not specifically allow an open stair between decks, a performance analysis may indicate that such an arrangement may not actually result in an unsafe situation.
Various tools are available to evaluate the impact of fires within compartments, and for tracking the movement products of combustion through a space. Simple analyses can provide a basic estimate of the conditions within a single room or for adjacent rooms. But these tools are not accurate or appropriate for complex geometry, and yachts are typically quite complex. More sophisticated methods, such as Computational Fluid Dynamics (CFD) modelling, are often needed to accurately characterise the conditions that can reasonably be expected during a ship fire. This level of accuracy is likewise generally necessary in order to demonstrate equivalency to the code.
In some cases, intensive CFD modelling – including sensitivity analyses and consideration of failures – may conclude that code-mandated elements are not required, and an alternate design can be proposed for review by the authorities. In other instances, however, the analysis might demonstrate that the provisions of the codes cannot be avoided. For instance, Figure 2 is derived from a CFD analysis undertaken to determine smoke spread from a fire in a stateroom. As seen in this figure, the fire in this case resulted in significant reduction in visibility in upper deck areas, and thus additional compartmentation was deemed necessary.
This analysis demonstrated that it was critical for fires in a stateroom to be confined to that room, to allow sufficient time for passengers to escape. However, the guestroom doors in this example have conflicting purposes. The doors need to be closed in the event of a fire in order to help contain smoke and heat but at the same time, the door to a stateroom containing an escape hatch needs to be openable by passengers needing to use this hatch in an emergency. To accomplish both of these roles, the doors to the staterooms can be equipped with magnetic hold-open devices (again, to support the desire for openness and functionality) and automatic closers, which close the doors upon alarm or manual activation on the bridge. The door that leads to the exit hatch can be additionally equipped with an electronic lock, so it can be unlocked by the crew on the bridge, automatically by the fire alarm system, or by occupants using a button adjacent to the door. The operation of this type of door arrangement should be clearly labelled, and crew training needs to be implemented.
Conclusions
In general, fire and life safety on a commercial or charter yacht is best accomplished by implementing a multi-level defence strategy. Various approaches are available for achieving such a strategy. The first level addresses compliance with prescriptive codes. A second level applies performance based analysis and design to provide practical solutions that demonstrate equivalence with the fire and life safety intent of the prescriptive code provisions. Strategy might include design elements such as compartmentation and egress components to achieve the goals of the design. Systems are available to support these elements, including physical barriers, detection systems, passenger notification systems, and suppression systems. An important component of this approach is proper maintenance and crew training, so that passengers are properly directed and assisted in evacuation, and that fire and life safety systems included in the design are used appropriately in the event of an emergency.
Richard Custer, Matthew Johann and Jeffrey Tubbs are from the Westborough, Massachusetts office of Arup Fire in the US.
References
1. IMO 2001. International Convention for the Safety of Life at Sea, International Maritime Association.
2. Lloyd’s Register 2001. Rules and Regulations for the Classification of Special Service Craft.
3. MCA, 2004. LY2: The Large Commercial Yacht Code. UK Maritime and Coastguard Agency.
