Out to sea
Apr 1, 1999 12:00 PM,
Until five years ago, the largest cruise ship afloat was only 75,000 grosstons. Currently, there are ships afloat that are more than 100,000 grosstons, 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 theincrease in the size of the ships, comes the increase in the size of theentertainment venues and the sound systems. The Grand Princess, which wasscheduled to sail in May 1998, is an elaborate, modern cruise ship. The twounique physical characteristics of the Grand Princess areits primaryentertainment areas. The Skywalkers Disco is designed into a giant tailfin, raised and isolated two decks above the structure of the ship andsuspended 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 bowarea of the vessel, is five decks high and will feature a complete flyrailsystem above its stage.
Greg Kirkland, a partner of Thomas-Gregor Associates, said, “Our FOHloudspeaker clusters on the Grand Princess will be the largest clusters wehave installed on a Princess ship. We are also installing more delay zonesand delay loudspeakers so we can get even coverage with highintelligibility.”
The budget for entertainment sound systems in a new-build ship project isapproximately 1% of the vessel’s overall cost. Therefore, when a cruisecompany is investing $500 million (US) to build a ship, as much as $5million or more will be invested on entertainment venue sound systems. Thebudgets for the sound systems are increasing with some of the cruise linesprobably spending as much as 2% of a ship’s overall budget on the sound.Cruise lines cannot cut budgets for entertainment because the one-upmanshipcompetition attracts the customers and drives the industry.
Thomas-Gregor Associates, El Segundo, CA, specializes in sea-going soundsystems. TGA was founded in 1984, in the same fashion as many other soundcontracting firms: in a garage, slowly phasing out of live sound touringwork and, by 1988, into full-time sound and vision installation projects.TGA’s ownership is made up of partners Greg Kirkland, Christian Hugener andGarrett Caine. As of 1998, TGA boasts a full-time staff of more than 20employees
Safe and secure rigging of elaborate ocean-going sound systems is a topicin which Kirkland is quite knowledgeable. TGA is based, and conducts muchof its business, in California, a major earthquake area. Therefore,Kirkland and staff are used to over-engineering rigging for flownloudspeakers and arrays. These practices carry over into their cruise shipprojects, where the SOLAS code (safety of life at sea), is more rigorousthan any land-based code. Everything involving wiring must meet certainfire, heat and shielding requirements, and rigging systems for loudspeakersare usually rated from 15:1 to 20:1.
As an example of the forces that act on a vessel, Kirkland said, “Thestabilization systems in modern cruise ships are amazing. Of course, youhave to designflown system to withstand the pitching and rolling of rough seas, but manypeople are not aware of the everyday forces that are put on a ship by thesteering and propelling systems. When a vessel is in port, and it fires upits bow thrusters, the vibration as the ship turns is equivalent to a 5.0earthquake. A land-based system will never encounter the constantvibrations or forces that are put upon the vessel by nature or generated bythe ship itself.
“TGA was responsible for fitting three theaters with the localentertainment systems aboard the Grand Princess, including sound, lighting,video and show control. TGA was also doing the main, aft and cabarettheaters aboard this vessel.
“After being in shipyards many times witnessing ships being built, I havenothing but the utmost respect for the engineering that goes into theconstruction of a cruise ship. Work on land-based buildings, even the mostelaborate skyscraper, cannot hold a candle to cruise ship work. A ship is aseries of steel-welded cubes and catacombs, all of which act upon eachother to transmit resonances.
“As Murphy’s Law would have it,” Kirkland continued, “the late-night anddisco venues, especially on older vessels, always seem to be sandwichedbetween, above or below, the most expensive cabins on the ship. The shipsunder construction have designed the discos to be far away from thepassenger areas.”
To contain the sound, namely the sub signals, to the entertainment venue,especially after the sound system is installed, sometimes seems impossibleto even the most knowledgeable and experienced contractor. Therefore, acomplex system design process is necessary to prevent sound from radiatingand bleeding throughout the vessel. The discos are usually where acontractor will find the greatest problems because they run late into thenight. Usually, the program material in the disco will change based uponthe theme of the cruise, thereby providing various resonance problems fromcruise to cruise. “These disco systems can easily do 120 dB or more,” saidKirkland. “Rarely does the staff ever push the systems to those extremesbecause the discos are usually fairly small spaces. A disco’s loudspeakersystem is usually installed into the dance floors, so the dance floor areagets 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 shipprojects while still in the design process. Several years ago, whilelooking for a mechanical method to overcome the transmission of resonancesfrom the ship’s hull, a friend in the construction industry informedKirkland of Mason Industries, which manufacturers vibration isolationunits, primarily for mechanical systems used in heavy industry and forseismic, HVAC and architectural applications. Although not specificallymanufactured for loudspeaker applications, the objective is thesame-isolate offending low-frequency resonances from their surroundings.Kirkland alleviates a ship’s sub-resonance problems with Mason’s flown andground-mounted isolators, which are made up of a series of heavy-dutyspring clamps combined with large rubber washers. These isolators aredesigned to decouple sound, especially bass, from resonating the decks andthe steel structure of the ship.
Kirkland said, “The isolators do not hurt the low end signal of the subbass performance. They are designed to isolate a loudspeaker or subwooferfrom the structure it is sitting in or flown from, and they work well. Onour last two Princess ships, the Sun Princess and the Dawn Princess, weused Mason isolators on any loudspeaker cabinet that produces any kind of alow-end frequency.”
Spring, neoprene and combination hangers are incorporated into a flownloudspeaker array’s flyware the same way they are used in modernconstruction applications. For instance, an application in which a localair-conditioning unit is flown above a dropped ceiling and below the upperfloor might incorporate these combination hangers into the AC unit’srigging. These isolating combination hangers might also be used in thesuspension hardware supporting the dropped ceiling to reduce all structuralvibrations generated by the air-conditioning unit. For isolatingsubwoofers, Mason shock pads and mounts, used with spring-mounted supports,secure the subwoofer to the ship’s structure and decouple the unit’svibration from its surroundings, which is the first step in eliminatingmany of the passenger complaints.
Another method to reduce sub bass transmission is to use a finely tunedparametric EQ to remove the unwanted frequency resonating through the decks.
“Or sometimes two decks below the loudspeaker,” said Kirkland. “We haveperformed this procedure in every installation to eliminate, or greatlyreduce, sub bass resonance. On several of the older vessels, we haveinstalled bigger, better, and louder systems. After isolating the systemmechanically, we use a broad spectrum frequency analyzer, and we walk theship where we believe, or have found, problems to exist. These are areasparallel, above and below the offending sound source. We excite thesubwoofer in the same fashion as it will be used on a regular basis, byusing various program material.”
A worst-case scenario is a recent refit of a disco system. The way the shipwas designed, the disco was right in the middle of the vessel on deckseven-almost in the heart of the ship-and the vessel was a total of about12 decks high. Passenger cabins completely surrounded the disco, directlyabove, below and to all sides. The offending frequency was in the area of30 Hz to 32 Hz, and the cabins that were getting the worst of thefrequencies were directly below the disco.
“The frequencies were just exploding the room,” said Kirkland. “Anythingloose was rattling-the toothbrush in its holder, closet doors and anythingelse laying around. It was such a powerful resonance that the toilet seatwas popping up and down with the beat of the music. What rattles the mostare the fittings, the halls, wall panels, dropped ceilings, anything thatis joined to the structure of the ship. You have to use a high-qualityparametric EQ to eliminate these resonances. The tightest possiblebandwidth is required to suck out the offending frequencies. My favorite EQis the Apogee Sound CRQ-12. We have good results just using a hand-heldIvie unit and the CRQ-12. With the tightest bandwidth possible, which iswhat the CRQ-12 offers, you can suck the life out of those tight offendingfrequencies. 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 willliterally go away and the system will still sound great.
“Once we attenuated that frequency, we took about 20 dB out, at less than1/6-octave. You could not hear the difference in response in the discobecause it was so tight a bandwidth, but exploding frequency in the cabinliterally disappeared.”
On board the S.S. IndependenceWith more than 35 years of experience, Miami Audio Video Company (MAVCO),serves many of the leading cruise lines in the world, including AmericanHawaiian, Carnival, Holland America, Norwegian, Royal Caribbean, Cunard,and Crystal Cruise Lines.
MAVCO project manager, Rex Stull said, “The lifecycle of a ship isforecasted to approximately 22 years. The entertainment systems areforecasted to last more than 10 years on a duty cycle, and that is with 10hour-a-day operation, 365 days per year minus a few days for dry dock. Theonly other similar use are the theme parks, but those systems do not havethe limited access of a cruise ship system. You will get a ship near aservice facility maybe eight hours per week or less. They arrive in themorning, and they depart in the early evening. Good luck in gettingsomething repaired or replaced.”
Granted, a ship’s indoor sound system is going to hold up far better thanan outdoor system. The salt atmosphere that surrounds a cruise ship reallydoes not have an effect on the internal disco and theater sound systems. Itis also rare that doors will be left open for any length of time, and theinterior areas are well air-conditioned. For the most part, it is normalwear-and-tear and misoperation that will cause breakdowns to the interiorsystems. So what happens when a high-powered system has to be installedpermanently on deck? Salt is as tenacious as most acids. Wood loudspeakers,regardless if they are the finest weatherized wood cabinets or musicstore-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’sstandards, the Independence is a fairly small vessel, weighing in at 40,000tons, and capable of entertaining as many as 800 passengers on frequentinter-island cruises. In June 1996, the Independence underwent a thoroughentertainment systems overhaul over a 10 day period during which all of theentertainment 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 upgradeaboard the Independence. In what to most contractors would seem like asimple dead-hang of two loudspeakers, there was more involved to ensure theloudspeakers 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 (381mm) cabinets used by the on-deck house band-can become a hazard in manyscenarios, especially when space is limited. A sudden pitch of the vesselor someone tripping on a cable, as well as other concerns-improving theoverall sound quality and the need for more deck space-were some of thereasons MAVCO was asked to modify the vessel’s main on-deck entertainmentarea.
Stull said, “When the ship is close to an island, the seas can be prettycalm and serene, but when the vessel travels from island to island, thewaters between the Hawaiian Islands can become fairly rough.”
Many ’50s-era ships were designed with aft pool decks as was theIndependence, unlike more modern designs in which the pool deck is centeredin the middle of the vessel. The simple sound system design for the aftpool deck became a bit more of a challenge when it was learned where theband’s stage area was located. The HALO, as it is affectionately known bythe crew of the Independence, is a large, steel circular structuresupported by arched I-beams. The HALO was designed with a series of smallchambers to support and shelter the outdoor stage lighting. It is underthis structure that the band performs. When the structure was added to theship, years after the vessel was set to sea, there was never aconsideration given for eventual safety needs to mount the band’sloudspeakers. To make matters more interesting, the HALO sits directly onthe rear-most section of the aft entertainment deck. When the bandperforms, it faces the bow of the vessel, directly into the wind as wouldall newly installed loudspeakers.
The entire aft pool/entertainment area is a fairly substantial piece ofdeck, according to Stull, and it makes up more than 100 ft (30 m) of theship’s overall length. Just in front of the stage is a dance floor, a smallseating 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 areafarthest away from the stern-there is another seating area and an open-airbar underneath the first mezzanine.
The first challenge to overcome was that the HALO structure had noaccommodations to support loudspeakers. Whatever supports needed to bebuilt would have to be custom-made. It was also theorized that anyloudspeaker installed in this manner would need to be replaced after eachcruise, and a fairly substantial loudspeaker, in terms of both size andoutput, would be needed to overcome the wind and be heard over the fulllength of the expansive deck.
Two Technomad WeatherTech 450 W BERLIN 15/H loudspeakers were chosen forthis particular installation for several reasons, the first beingTechnomad’s weatherization characteristics of its products. Designed torigorous military specifications, Technomad loudspeakers are fullyresistant against water, sand, salt, temperature, chemical and otherdamage. Technomad’s 3/4 inch (19 mm) thick, one-piece, rotomolded cabinets,weatherized proprietary drivers, multi-layer acoustically transparentWeatherTech grills, and water-tight lids convinced the customer thisloudspeaker was going to last longer than others. Yordi was satisfied withthe size of the loudspeakers, wanting to avoid large, multiple cabinetsthat could detract from the Hawaiian sunsets and other scenery viewed fromthe aft entertainment deck. Small and low-profile, 210x330x10.50 (533 mm x838 mm x 267 mm) and weighing only 90 pounds (40.5 kg), the TechnomadBERLIN 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 respectthat they feature water-tight lids, so they can be sealed up in harshweather when they need to be washed down or safely transported. When theloudspeakers are active, the lids can be latched to the back of theloudspeaker cabinet to prevent loss. The customer liked this aspect, and heinsisted the loudspeakers retain this feature. Therefore, in designing themounts, no part of the mounting structure was to obstruct the back of theloudspeaker cabinet to encumber the use of the lids.”
The BERLIN loudspeakers also have four aligned, 1.5 inch (38.1 mm) diameterstandmount sockets, one on each side of the cabinet. Many Technomadloudspeakers are also the same depth, 10.5 inches (267 mm). In mobileapplications, Technomad loudspeakers all interlock via 6 inch (152 mm)long, 1.5 inch (38.1 mm) diameter tubes inserted into correspondingtop-to-bottom and side-to-side standmount sockets, allowing theloudspeakers to form strong ridged-stacked arrays. This stacking featurealso allowed the development of a unique method to secure the loudspeakersinto their mounts.
A rectangular, steel-welded support frame, prefabricated from 5/8 inch (16mm) thick steel, was designed to enclose the loudspeaker, leaving the backand the front of the cabinet exposed. The frames were then attached to anexisting lag bolt-point on the HALO. The inside dimensions of the frameworkmatch the height, width and depth of the BERLIN loudspeaker cabinet,preventing it from tilting forward or backward in its frame once theloudspeaker is in place. Yordi then designed a simple quick-release lockingsystem featuring two, 4 inch (102 mm) long, 1.5 inch (38.1 mm) diameterrods because the loudspeaker needed to be easily removable for eventualgeneral maintenance. These two rods key through the mounting frame, andlock into the BERLIN’s side standmount sockets, firmly securing theloudspeaker into the frame.
“There is no way for the loudspeaker to move around in this frame,” saidYordi. “Built to 20:1 weight ratio, the tolerance is tight enough so theloudspeakers can slide in, and once the locking pins are installed, theloudspeakers are secure. We came up with a lot of ideas about how toinstall these loudspeakers, and this design was the final one we submitted.Clearly, it was the simplest; it was therefore the one approved byeverybody involved.”
Loudspeaker termination is always a point of contention, especially inapplications in close proximity to salt water. A weatherized junction boxwas also added to the HALO. The band’s power and processing rack is wheeledout and simply plugged into the Technomad loudspeaker system.
Yordi said, “We left the standard Neutrik connectors as is. There was nospecial termination added to the BERLIN, and the Neutriks are holding upwell. The loudspeakers were installed in June 1996, and as of this date, inspite of the conditions at sea, there have been no complaints about thisparticular system installation. The loudspeakers have been holding up well.So well, in fact, chance are that they probably have never covered themwith their lids.”
Stull said, “The Technomads are not huge in comparison to similarlyconfigured loudspeakers, so it is really shocking to hear that amount ofsound coming out of those little cabinets. The horn on the BERLIN has agreat throw distance, and normally on a ship’s open deck, you get amuffled, ineffectual sound. The BERLINs were clear, and they cut throughthe noise of the environment and crosswinds without harshness, and theyhave great low-end response that did not weaken over great distances. Thecustomer was surprised and ultimately thrilled by the performance of theTechnomads. Now, however, after almost two years of ocean exposure, theruggedness and reliability of the Technomads is what has us all amazed.
Concluding, Kirkland said, “If a contractor is not willing to take the timeto do the math and securely rig any flying system, regardless if it is anat-sea or a land-based installation, then he is just another kid tryingthis at home. Rigging loudspeakers aboard a cruise ship is never the placefor experimentation or shortcuts. You probably remember a situation wheresomeone stated, ‘You know, we do not need those extra lifeboats.’ Thedisastrous outcome of that careless short-cut is the stuff movies are madeof.