Out to sea
Apr 1, 1999 12:00 PM, Rich Williams
Until five years ago, the largest cruise ship afloat was only 75,000 gross tons. Currently, there are ships afloat that are more than 100,000 gross tons, with new ships on the books for 140,000 gross tons. There has been, and continues to be, a tremendous increase in ship size, and with the increase in the size of the ships, comes the increase in the size of the entertainment venues and the sound systems. The Grand Princess, which was scheduled to sail in May 1998, is an elaborate, modern cruise ship. The two unique physical characteristics of the Grand Princess areits primary entertainment areas. The Skywalkers Disco is designed into a giant tail fin, raised and isolated two decks above the structure of the ship and suspended 15 decks above the sea. The main showroom, the Princess Theater, complete with a 36 ft (11 m) proscenium arch stage and located in the bow area of the vessel, is five decks high and will feature a complete flyrail system above its stage.
Greg Kirkland, a partner of Thomas-Gregor Associates, said, "Our FOH loudspeaker clusters on the Grand Princess will be the largest clusters we have installed on a Princess ship. We are also installing more delay zones and delay loudspeakers so we can get even coverage with high intelligibility."
The budget for entertainment sound systems in a new-build ship project is approximately 1% of the vessel's overall cost. Therefore, when a cruise company is investing $500 million (US) to build a ship, as much as $5 million or more will be invested on entertainment venue sound systems. The budgets for the sound systems are increasing with some of the cruise lines probably spending as much as 2% of a ship's overall budget on the sound. Cruise lines cannot cut budgets for entertainment because the one-upmanship competition attracts the customers and drives the industry.
Thomas-Gregor Associates, El Segundo, CA, specializes in sea-going sound systems. TGA was founded in 1984, in the same fashion as many other sound contracting firms: in a garage, slowly phasing out of live sound touring work and, by 1988, into full-time sound and vision installation projects. TGA's ownership is made up of partners Greg Kirkland, Christian Hugener and Garrett Caine. As of 1998, TGA boasts a full-time staff of more than 20 employees
Safe and secure rigging of elaborate ocean-going sound systems is a topic in which Kirkland is quite knowledgeable. TGA is based, and conducts much of its business, in California, a major earthquake area. Therefore, Kirkland and staff are used to over-engineering rigging for flown loudspeakers and arrays. These practices carry over into their cruise ship projects, where the SOLAS code (safety of life at sea), is more rigorous than any land-based code. Everything involving wiring must meet certain fire, heat and shielding requirements, and rigging systems for loudspeakers are usually rated from 15:1 to 20:1.
As an example of the forces that act on a vessel, Kirkland said, "The stabilization systems in modern cruise ships are amazing. Of course, you have to design flown system to withstand the pitching and rolling of rough seas, but many people are not aware of the everyday forces that are put on a ship by the steering and propelling systems. When a vessel is in port, and it fires up its bow thrusters, the vibration as the ship turns is equivalent to a 5.0 earthquake. A land-based system will never encounter the constant vibrations or forces that are put upon the vessel by nature or generated by the ship itself.
"TGA was responsible for fitting three theaters with the local entertainment systems aboard the Grand Princess, including sound, lighting, video and show control. TGA was also doing the main, aft and cabaret theaters aboard this vessel.
"After being in shipyards many times witnessing ships being built, I have nothing but the utmost respect for the engineering that goes into the construction of a cruise ship. Work on land-based buildings, even the most elaborate skyscraper, cannot hold a candle to cruise ship work. A ship is a series of steel-welded cubes and catacombs, all of which act upon each other to transmit resonances.
"As Murphy's Law would have it," Kirkland continued, "the late-night and disco venues, especially on older vessels, always seem to be sandwiched between, above or below, the most expensive cabins on the ship. The ships under construction have designed the discos to be far away from the passenger areas."
To contain the sound, namely the sub signals, to the entertainment venue, especially after the sound system is installed, sometimes seems impossible to even the most knowledgeable and experienced contractor. Therefore, a complex system design process is necessary to prevent sound from radiating and bleeding throughout the vessel. The discos are usually where a contractor will find the greatest problems because they run late into the night. Usually, the program material in the disco will change based upon the theme of the cruise, thereby providing various resonance problems from cruise to cruise. "These disco systems can easily do 120 dB or more," said Kirkland. "Rarely does the staff ever push the systems to those extremes because the discos are usually fairly small spaces. A disco's loudspeaker system is usually installed into the dance floors, so the dance floor area gets the majority of the system output. There is no way of telling where, or when, resonances can materialize until the system is fully tested."
TGA enjoys success in eliminating resonance problems in new build ship projects while still in the design process. Several years ago, while looking for a mechanical method to overcome the transmission of resonances from the ship's hull, a friend in the construction industry informed Kirkland of Mason Industries, which manufacturers vibration isolation units, primarily for mechanical systems used in heavy industry and for seismic, HVAC and architectural applications. Although not specifically manufactured for loudspeaker applications, the objective is the same-isolate offending low-frequency resonances from their surroundings. Kirkland alleviates a ship's sub-resonance problems with Mason's flown and ground-mounted isolators, which are made up of a series of heavy-duty spring clamps combined with large rubber washers. These isolators are designed to decouple sound, especially bass, from resonating the decks and the steel structure of the ship.
Kirkland said, "The isolators do not hurt the low end signal of the sub bass performance. They are designed to isolate a loudspeaker or subwoofer from the structure it is sitting in or flown from, and they work well. On our last two Princess ships, the Sun Princess and the Dawn Princess, we used Mason isolators on any loudspeaker cabinet that produces any kind of a low-end frequency."
Spring, neoprene and combination hangers are incorporated into a flown loudspeaker array's flyware the same way they are used in modern construction applications. For instance, an application in which a local air-conditioning unit is flown above a dropped ceiling and below the upper floor might incorporate these combination hangers into the AC unit's rigging. These isolating combination hangers might also be used in the suspension hardware supporting the dropped ceiling to reduce all structural vibrations generated by the air-conditioning unit. For isolating subwoofers, Mason shock pads and mounts, used with spring-mounted supports, secure the subwoofer to the ship's structure and decouple the unit's vibration from its surroundings, which is the first step in eliminating many of the passenger complaints.
Another method to reduce sub bass transmission is to use a finely tuned parametric EQ to remove the unwanted frequency resonating through the decks.
"Or sometimes two decks below the loudspeaker," said Kirkland. "We have performed this procedure in every installation to eliminate, or greatly reduce, sub bass resonance. On several of the older vessels, we have installed bigger, better, and louder systems. After isolating the system mechanically, we use a broad spectrum frequency analyzer, and we walk the ship where we believe, or have found, problems to exist. These are areas parallel, above and below the offending sound source. We excite the subwoofer in the same fashion as it will be used on a regular basis, by using various program material."
A worst-case scenario is a recent refit of a disco system. The way the ship was designed, the disco was right in the middle of the vessel on deck seven-almost in the heart of the ship-and the vessel was a total of about 12 decks high. Passenger cabins completely surrounded the disco, directly above, below and to all sides. The offending frequency was in the area of 30 Hz to 32 Hz, and the cabins that were getting the worst of the frequencies were directly below the disco.
"The frequencies were just exploding the room," said Kirkland. "Anything loose was rattling-the toothbrush in its holder, closet doors and anything else laying around. It was such a powerful resonance that the toilet seat was popping up and down with the beat of the music. What rattles the most are the fittings, the halls, wall panels, dropped ceilings, anything that is joined to the structure of the ship. You have to use a high-quality parametric EQ to eliminate these resonances. The tightest possible bandwidth is required to suck out the offending frequencies. My favorite EQ is the Apogee Sound CRQ-12. We have good results just using a hand-held Ivie unit and the CRQ-12. With the tightest bandwidth possible, which is what the CRQ-12 offers, you can suck the life out of those tight offending frequencies. You will not affect the response of the system that greatly, but you will knock a good 6 dB to 8 dB out of the resonance, and it will literally go away and the system will still sound great.
"Once we attenuated that frequency, we took about 20 dB out, at less than 1/6-octave. You could not hear the difference in response in the disco because it was so tight a bandwidth, but exploding frequency in the cabin literally disappeared."
On board the S.S. Independence With more than 35 years of experience, Miami Audio Video Company (MAVCO), serves many of the leading cruise lines in the world, including American Hawaiian, Carnival, Holland America, Norwegian, Royal Caribbean, Cunard, and Crystal Cruise Lines.
MAVCO project manager, Rex Stull said, "The lifecycle of a ship is forecasted to approximately 22 years. The entertainment systems are forecasted to last more than 10 years on a duty cycle, and that is with 10 hour-a-day operation, 365 days per year minus a few days for dry dock. The only other similar use are the theme parks, but those systems do not have the limited access of a cruise ship system. You will get a ship near a service facility maybe eight hours per week or less. They arrive in the morning, and they depart in the early evening. Good luck in getting something repaired or replaced."
Granted, a ship's indoor sound system is going to hold up far better than an outdoor system. The salt atmosphere that surrounds a cruise ship really does not have an effect on the internal disco and theater sound systems. It is al so rare that doors will be left open for any length of time, and the interior areas are well air-conditioned. For the most part, it is normal wear-and-tear and misoperation that will cause breakdowns to the interior systems. So what happens when a high-powered system has to be installed permanently on deck? Salt is as tenacious as most acids. Wood loudspeakers, regardless if they are the finest weatherized wood cabinets or music store-bought carpeted cabinets, will be reduced to non-musical, squawking, de-laminating hulks of plywood and rusting metal after only six months.
American Hawaiian's S.S. Independence was built in the '50s. By today's standards, the Independence is a fairly small vessel, weighing in at 40,000 tons, and capable of entertaining as many as 800 passengers on frequent inter-island cruises. In June 1996, the Independence underwent a thorough entertainment systems overhaul over a 10 day period during which all of the entertainment venues were upgraded to the newest technologies. Amir Yordi, engineer coordinator for MAVCO's Maritime Design Division, and Stull, discussed one small, yet challenging, aspect of the overall systems upgrade aboard the Independence. In what to most contractors would seem like a simple dead-hang of two loudspeakers, there was more involved to ensure the loudspeakers would perform properly, survive the rigors of full-time, open-ocean exposure and stay exactly where they were to be installed. Safety concerns for passengers and crew are always a top priority. Unsecured entertainment loudspeakers-like a pair of two-way 15 inch (381 mm) cabinets used by the on-deck house band-can become a hazard in many scenarios, especially when space is limited. A sudden pitch of the vessel or someone tripping on a cable, as well as other concerns-improving the overall sound quality and the need for more deck space-were some of the reasons MAVCO was asked to modify the vessel's main on-deck entertainment area.
Stull said, "When the ship is close to an island, the seas can be pretty calm and serene, but when the vessel travels from island to island, the waters between the Hawaiian Islands can become fairly rough."
Many '50s-era ships were designed with aft pool decks as was the Independence, unlike more modern designs in which the pool deck is centered in the middle of the vessel. The simple sound system design for the aft pool deck became a bit more of a challenge when it was learned where the band's stage area was located. The HALO, as it is affectionately known by the crew of the Independence, is a large, steel circular structure supported by arched I-beams. The HALO was designed with a series of small chambers to support and shelter the outdoor stage lighting. It is under this structure that the band performs. When the structure was added to the ship, years after the vessel was set to sea, there was never a consideration given for eventual safety needs to mount the band's loudspeakers. To make matters more interesting, the HALO sits directly on the rear-most section of the aft entertainment deck. When the band performs, it faces the bow of the vessel, directly into the wind as would all newly installed loudspeakers.
The entire aft pool/entertainment area is a fairly substantial piece of deck, according to Stull, and it makes up more than 100 ft (30 m) of the ship's overall length. Just in front of the stage is a dance floor, a small seating area and then the pool. There are seating areas left and right (port and starboard) of the pool, and at the far side of the pool-the area farthest away from the stern-there is another seating area and an open-air bar underneath the first mezzanine.
The first challenge to overcome was that the HALO structure had no accommodations to support loudspeakers. Whatever supports needed to be built would have to be custom-made. It was also theorized that any loudspeaker installed in this manner would need to be replaced after each cruise, and a fairly substantial loudspeaker, in terms of both size and output, would be needed to overcome the wind and be heard over the full length of the expansive deck.
Two Technomad WeatherTech 450 W BERLIN 15/H loudspeakers were chosen for this particular installation for several reasons, the first being Technomad's weatherization characteristics of its products. Designed to rigorous military specifications, Technomad loudspeakers are fully resistant against water, sand, salt, temperature, chemical and other damage. Technomad's 3/4 inch (19 mm) thick, one-piece, rotomolded cabinets, weatherized proprietary drivers, multi-layer acoustically transparent WeatherTech grills, and water-tight lids convinced the customer this loudspeaker was going to last longer than others. Yordi was satisfied with the size of the loudspeakers, wanting to avoid large, multiple cabinets that could detract from the Hawaiian sunsets and other scenery viewed from the aft entertainment deck. Small and low-profile, 210x330x10.50 (533 mm x 838 mm x 267 mm) and weighing only 90 pounds (40.5 kg), the Technomad BERLIN delivers an accurate 50 Hz to 17.5 kHz at up to 127 dB continuous.
Yordi said, "The Technomad BERLIN loudspeakers are unique in the respect that they feature water-tight lids, so they can be sealed up in harsh weather when they need to be washed down or safely transported. When the loudspeakers are active, the lids can be latched to the back of the loudspeaker cabinet to prevent loss. The customer liked this aspect, and he insisted the loudspeakers retain this feature. Therefore, in designing the mounts, no part of the mounting structure was to obstruct the back of the loudspeaker cabinet to encumber the use of the lids."
The BERLIN loudspeakers also have four aligned, 1.5 inch (38.1 mm) diameter standmount sockets, one on each side of the cabinet. Many Technomad loudspeakers are also the same depth, 10.5 inches (267 mm). In mobile applications, Technomad loudspeakers all interlock via 6 inch (152 mm) long, 1.5 inch (38.1 mm) diameter tubes inserted into corresponding top-to-bottom and side-to-side standmount sockets, allowing the loudspeakers to form strong ridged-stacked arrays. This stacking feature also allowed the development of a unique method to secure the loudspeakers into their mounts.
A rectangular, steel-welded support frame, prefabricated from 5/8 inch (16 mm) thick steel, was designed to enclose the loudspeaker, leaving the back and the front of the cabinet exposed. The frames were then attached to an existing lag bolt-point on the HALO. The inside dimensions of the framework match the height, width and depth of the BERLIN loudspeaker cabinet, preventing it from tilting forward or backward in its frame once the loudspeaker is in place. Yordi then designed a simple quick-release locking system featuring two, 4 inch (102 mm) long, 1.5 inch (38.1 mm) diameter rods because the loudspeaker needed to be easily removable for eventual general maintenance. These two rods key through the mounting frame, and lock into the BERLIN's side standmount sockets, firmly securing the loudspeaker into the frame.
"There is no way for the loudspeaker to move around in this frame," said Yordi. "Built to 20:1 weight ratio, the tolerance is tight enough so the loudspeakers can slide in, and once the locking pins are installed, the loudspeakers are secure. We came up with a lot of ideas about how to install these loudspeakers, and this design was the final one we submitted. Clearly, it was the simplest; it was therefore the one approved by everybody involved."
Loudspeaker termination is always a point of contention, especially in applications in close proximity to salt water. A weatherized junction box was also added to the HALO. The band's power and processing rack is wheeled out and simply plugged into the Technomad loudspeaker system.
Yordi said, "We left the standard Neutrik connectors as is. There was no special termination added to the BERLIN, and the Neutriks are holding up well. The loudspeakers were installed in June 1996, and as of this date, in spite of the conditions at sea, there have been no complaints about this particular system installation. The loudspeakers have been holding up well. So well, in fact, chance are that they probably have never covered them with their lids."
Stull said, "The Technomads are not huge in comparison to similarly configured loudspeakers, so it is really shocking to hear that amount of sound coming out of those little cabinets. The horn on the BERLIN has a great throw distance, and normally on a ship's open deck, you get a muffled, ineffectual sound. The BERLINs were clear, and they cut through the noise of the environment and crosswinds without harshness, and they have great low-end response that did not weaken over great distances. The customer was surprised and ultimately thrilled by the performance of the Technomads. Now, however, after almost two years of ocean exposure, the ruggedness and reliability of the Technomads is what has us all amazed.
Concluding, Kirkland said, "If a contractor is not willing to take the time to do the math and securely rig any flying system, regardless if it is an at-sea or a land-based installation, then he is just another kid trying this at home. Rigging loudspeakers aboard a cruise ship is never the place for experimentation or shortcuts. You probably remember a situation where someone stated, 'You know, we do not need those extra lifeboats.' The disastrous outcome of that careless short-cut is the stuff movies are made of.
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