Majesty of the Seas upgrades PA and alarm system

(16/04/2009)

With a displacement of nearly 74,000 tons, the Majesty of the Seas was one of the largest cruise ships in the world at the time of her completion in 1991. Accommodating up to 2,744 passengers and 820 crew, she is chiefly employed by Royal Caribbean on luxury cruises departing from Miami, Florida, and stopping at ports such as Nassau, Coco Cay (a private island owned by Royal Caribbean) and the Florida coastal resort of Key West.

Royal Caribbean International’s luxury cruise ship Majesty of the Seas recently underwent a multi-million dollar top-to-bottom refurbishment at the Grand Bahamas Shipyard in Freeport, Bahamas. An important part of the project was a complete upgrade of the ship’s PA and alarm installation from its well-proven but ageing Philips SM-40 system to the new Bosch Praesideo Digital Public Address and Emergency Sound System.

During the renovation, the owners also took the opportunity to completely upgrade the ship’s PA and emergency sound system to bring it up to modern standards. The owners contracted the project out to the Miami branch of Harbour Marine Systems with the request that the installers find them a turnkey solution to provide, in effect, a drop-in replacement for the ship’s SM-40 system.

“Royal Caribbean effectively gave us a free rein in the choice of new sound system, provided it would fully meet the needs of a large passenger ship like the Majesty and also the high standards of Royal Caribbean’s marine classification agency Det Norske Veritas,” explains Tim Rodriguez, AV engineer specializing in public address at Harbour Marine Systems.

Many of the cruise ships operating in the Caribbean have ageing sound systems and Harbour Marine Systems has been promoting Bosch’s Praesideo Digital Public Address and Emergency Sound System as a replacement for some years. “We see it as today’s premier PA system, not only because of the excellent digital sound quality, but also because of the ease with which it can be adapted to a ship’s environment,” says Tim Rodriguez. “This project gave us an excellent opportunity to demonstrate the system’s outstanding qualities.”

Safety at sea is paramount and a ship’s sound system must function 100 per cent at all times, especially in the event of an emergency. “The sound system is, in fact, one of the few systems on board that will keep the ship tied to the dock if it’s not functioning properly,” points out Tim Rodriguez, “every aspect of the PA system must be totally reliable.”

In this respect, the Praesideo was the first public address and emergency sound system to receive IEC 60849 certification, awarded by TÜV, the renowned German quality and safety organization in April 2003. It has also been certified by TÜV to the BS 5839 standard for fire detection and fire alarm systems, and is SOLAS certified for off-shore applications and proven reliability even in harsh conditions at sea.

The ship has a rather unusual arrangement with the public rooms located aft, while all passenger and crew accommodation is in the forward section of the ship. According to modern shipbuilding practice, a ship’s PA system is divided into separate fire zones, but in older ships it was more usual to centralize the PA system at one head-end location. In the Majesty of the Seas this is in the TV broadcast room, and cabling for thousands of speakers, including those in all the staterooms as well as the filtering and control systems for muting the local entertainment systems, are all routed into this room.

“To break it up into different areas you’d be talking about a massive amount of recabling,” emphasizes Tim Rodriguez. “So basically the project involved removing all existing equipment and installing the new amplifiers, network controllers and relay controllers in this one room. What’s more, with the exception of the deck speakers, many of which were replaced as part of the general refurbishment, the new system made use of the original speakers.”

The PA system incorporates six remote call stations and one standard call station installed in the TV broadcast room, plus 21 keypads used between the various call stations.

The ship is divided into 27 zones arranged into 20 zone groupings. The Purser’s desk, for example, through which many passenger public-area calls and general calls for passengers are made, is on a different grouping to, say, the Engine Control room which covers all the technical spaces within the ship. The bridge is primarily an emergency call station with connection to all the zones via duplicated electronics. This can take control of the PA and alarm system in the event of a Network Controller failure. The system also incorporates nineteen 500 W amplifiers and seven 2 x 250 W amplifiers to meet the power requirements of each specific zone of the ship, plus two network controllers (one redundant).

One of the challenges that installers often encounter is the unreliability of a ship’s documentation after it has been around for some years, since a lot of changes are made that are undocumented. Although a buffer is usually built into the installation time to allow for this, the marine classification agency Det Norske Veritas (DNV) added extra requirements. These included the requirement that the PA system should be able to temporarily interrupt all the ship’s emergency alarm signals with just a single button to make an emergency or other important announcement.

“With the lack of up-to-date documentation, this took some effort and we had to be a bit creative,” points out Tim Rodriguez. “But every aspect of the Praesideo is so flexible – the control inputs, control outputs and its programming characteristics – that basically it’s very easy to adapt it to almost any situation you’re likely to encounter. You can, for example, take contact closure inputs to start a certain type of announcement while simultaneously creating an emergency state. This flexibility made it much easier to meet DNV’s specifications, which I don’t think could have been met to the degree required with the old system.”

Possible fire hazards caused by welding during the refit also meant that it was essential for the ship’s on-board sound system to remain operational throughout the dry-dock period. This was ensured by keeping the SM-40 system connected while the Praesideo was installed in the TV broadcast room and then switching over from the old to the new system amplifier-by-amplifier to maintain zero downtime.

Tim Rodriguez commented “We were able to do a lot of the preliminary programming before taking the Praesideo onto the ship. Then it was a matter of fine-tuning and adapting it to the specific situation we encountered on board and to meet the requirements set by DNV. During the setting up and programming, we also received excellent support from Bosch. We were able to talk directly with the developers at Bosch and resolve questions. And we were even able to provide feedback on some software issues that Bosch has now corrected in later updates.”

In addition to retrofits like the one on Majesty of the Seas, Harbour Marine Systems is also involved in installing Praesideo Public Address and Emergency Sound Systems into new ships.

Related topics:  Public Address system 

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