Gravity is one of those things that you take for granted — but there are places on earth where gravity doesn't always work as expected. One such place is the water. We all know that unexpected things happen in the water that seem to defy gravity, but most of us are unaware that these unexpected behaviors can also happen on the water. Normally, this can result in a fair amount of amusement, but there are situations where the ramifications can be dangerous. Such situations occur when moving heavy pieces of scenery or live performers at sea. As the entertainment options aboard cruise ships have grown more sophisticated over the past few years, so have the requirements for the stage machinery and rigging systems.
While the design approach to these rigging and stage systems is certainly based on the same principles as land-based applications, there are a number of considerations unique to designing for a maritime environment. The majority of these considerations are based around one simple, unalterable fact: The theatre and stage are not stationary — they move. As part of the design team at Nautilus Entertainment Design (NED), responsible for designing the entertainment facilities aboard a majority of the cruise industry vessels currently in development, we have become intimate with these issues over the past several years and developed a variety of methods to adapt to the special demands of rigging at sea.
Rigging systems — even the motorized systems that are used exclusively onboard ships — make use of the natural acceleration caused by gravity. Due to the pitch, yaw, and roll of a ship, maritime rigging installations have to take into account other accelerations caused by this ship movement that can be two or even three times that attributed to gravity. Additionally, land-based rigging systems can always use gravity to their advantage. At sea, you can't take gravity for granted. In heavy seas, negative gravity situations can cause things to fall up; down isn't always down. Conversely, those same seas can cause things to fall down at a significantly increased rate, which can pound the theatre equipment as if the entire theatre were dropped to the ground from 5' in the air.
The Carnival Cruise Lines Carnival Pride, part of CCL's Fun Fleet
This means that the size of the motors and possibly other components must be increased due to this greater force of unpredictable seas. Perversely, while oversized, the components must be as light as possible. Size and space are limited onboard ships, and weight is an ongoing concern with naval architects. For example, maritime battens are usually made of aluminum rather than steel. This means the batten weight does not detract substantially from the winch weight capacity, allowing more scenic lifting capability — or reducing winch size if greater capacity is not needed.
Another design consideration is vibration. Most onboard ship theatres are located toward the front of the ship, over the bow-maneuvering thrusters. Thrusters are propellers built into the ship's hull, which are used to push the ship sideways during docking procedures. These can be activated as often as three times a day and have the force to cause the entire theatre to tremble. This means that threaded fasteners, a mainstay of land-based rigging, are avoided whenever possible. Painstaking steps are taken with the remaining threaded fasteners to ensure they won't be worked loose due to the ship's vibrations. Each nut and bolt is inspected during the installation and commissioning procedure and various forms of safety measures — ranging from drilling and pinning to applying Lok-Tight™ or scoring the threads to prevent the nut from being removed at all — are used to fix the connections.
Because of the gravity situation, low ceiling height, and space limitations, most maritime overhead rigging systems are multidrum lineshaft systems with variable speed drive. The flyloft width aboard ships is limited by the space between the two fore/aft hallways on the upper cabin decks. This width is usually slightly greater than the width of the proscenium, generally in the 11m range, with a stage proscenium opening of 9m to 10m. With a multidrum lineshaft, all of the rigging can be contained in the upper ceiling of the flyloft and each lineset controlled by one drive and lifted by one motor. Using a winch system rather than a multidrum lineshaft system would require one winch and motor per lift line — typically five to seven per lineset — and then routing all of the lift lines to winch drums. Routing all of the cables around the guide system and other obstructions would be difficult enough, but it would also add more friction and complexity to the system. Additionally, counterweight systems are ruled out due to the inherent danger of having loose weights carried around in a moving theatre.
Typically, all overhead rigging systems on ships are designed with variable speed motor drives, which allow for smooth accelerations and decelerations. This reduces the shock load during the starting and stopping of the piece attached to the batten. If the sets were fixed speed, it would be very difficult to have smooth transitions as well as repeated accuracy.
Over the relatively short time that complex rigging systems have been installed on ships, various systems have been developed to stabilize the system components from the movement of the ship. All rigging components must use captured guide systems to maintain alignment — of not only the battens but also the scenery attached to them. If only the battens are guided, the scenery will swing as a pendulum from the batten. As such, movement throughout full travel must be controlled. As an added concern, not only does the stage move, but also the entire theatre and flyloft flexes, expands, contracts, and twists as the ship moves through the sea. This means that the guides have to be designed to be tight enough to hold the batten and scenery frame without being so tight as to increase the friction in warmer areas when the materials expand.
The first systems installed that guided not only the battens but also the scenery frames were introduced on the Costa Cruise Lines' Atlantica class in 2000. The guide systems are straightforward and similar to land-based counterweight arbor guides. Typically, there is either a T-Guide or channel guide integrated into the ship's steel structure. A mating shoe or roller guide is then designed into the ends of the battens. There are a number of additional issues:
- The guide shoe system must be adjustable since the guides are not always installed plumb.
- The guides and shoes must work with a minimum of friction when the battens are not plumb to the stage floor, as is typical when the ship is moving.
- The guide shoes must be durable for a long lifespan.
- The guide shoes must be self-lubricating.
- The guide channels must be designed to allow for easy and smooth threading of battens and scenery into the guide channels.
In my opinion, designing orchestra lifts and other stage machinery when space is limited — and there is no ground to dig into — also requires a new approach. There is no space for typical stage machinery lifting systems, usually screw-jack with caissons. Self-collapsing drive chain systems are often the solution. Everything must be low profile and fit within 400mm to 600mm of space in storage, yet extend up to 1.5m above the stage level. The lifts must also be able to drive at up to 300mm (1') per second. Additionally, due to the possible negative gravity situation, stage machinery drive systems must be stable in both compression and tension situations. To meet these new constraints, machinery manufacturers have had to alter their land-based designs — which only have to accommodate standard gravity conditions — to be able to handle the constantly changing accelerations, pitch, yaw, and vibrations experienced in a maritime theatre. Not only do the stage mechanics need to take into account the movement and gravity, but also to be considered is the rolling scenery, as this requires tracks built into the floor as guides and to function as anchors in some cases.
a Mechatronics control console, used on the Carnival Pride
Modern cruise ships have grown to include several different types of stage machinery systems. Most can be found to have large orchestra lift platforms that retract one full deck below the stage for use with musicians as well as choreographed entrances and escapes. Varying types of performance lifts have also been integrated into these ships' stages. Some have large turntables with large mechanical staircase units, which rise out of the stage. Others have multiple self-supported, independent stage lifts capable of rising 1.5m above the stage at 300mm/s. All moving lifts are designed with touch-sensitive safe edges at all possible pinch points. When the safe edges sense an object in a potential pinch point, the control system shuts down all mechanics in the rigging system. This requires a visual check and reset before continuing operation of the rigging system. The safe edges are also important components of motorized bandwagons where performers are on and around the wagon as they are moving. If an object or a performer were to obstruct the movement of the wagon, the safety edge would detect the obstacle and stop the movement until the obstruction was removed.
Because so little scenery storage space is available, our firm is constantly working with the owners to provide new ways of using integrated stage machinery within the shows in order to reduce the amount of hard scenery required onstage. One example of this is a full stage flying videowall for the new Queen Mary 2, which can be programmed for both static and moving images.
The technical crews are smaller on ships than land-based facilities. A smaller crew means that each technician must wear many different hats. Also, some of the people who act as stage crew may actually only be on loan to the theatre for that evening's performance. Typically, they have other jobs — as waiters, welders, or stewards — and are used by the technical staff as extra hands to assist running the stage area during large performances. In addition, the only dedicated personnel are a lighting tech, a sound tech, and a stage manager who operates the main rigging control system for the large production shows.
The control systems currently being used on ships have been developed by the manufacturers in conjunction with NED and the owners' requirements in order to provide safe, reliable control of even the most complex moves. Due to the limited personnel, production shows at sea are typically run from SMPTE timecode, so everything is synchronized to a show control system. For safety, however, NED does not design systems where SMPTE can actually move any of the rigging pieces. Rather than having the show control system execute a lineset or lift move, the SMPTE just loads the rigging cues to the desired playback fader, telling the computer what is supposed to come next, while a stagehand executes the cue after visually verifying that the space is clear and there are no dangers to performers or other scenic pieces.
During the development of each ship, the control systems are customized to each space's unique requirements. A system of limit switch interlocks are designed into the control computer to help the computer know where all rigging components are before it allows any piece to be moved. This is something that typically would be done by a live person on a land-based show. Due to the limited personnel and their limited experience, the computer adds another level of safety — and inevitable complexity.
Regarding safety, the regulatory concerns aboard ships are still evolving. While the entertainment facility design does not fall specifically under anyone's jurisdiction, several different associations require input and approval of the stage machinery designs. The ship's underwriters (usually Lloyd's of London or Italy's RINA) must sign off on the design of anything that moves people or is related to life safety. The United States Coast Guard also has some regulatory responsibilities relating to safety systems and passenger emergency procedures because the ships are registered for US waters.
We have seen an explosion in the technology of maritime entertainment facilities over the past decade and the complexity of the issues related to rigging at sea may be a surprise to the uninitiated. The experience NED has gained from designing many of these systems (14 ships in seven years) and working with the cruise lines' entertainment departments has allowed them to evolve their approach, with installations that meet the stringent production demands — while always keeping safety first.
Michael Lindauer joined Nautilus Entertainment Design in 1999, where he currently serves as associate consultant and project manager. Prior to joining NED, he worked at JR Clancy and Show Tech designing mechanized rigging systems and motorized scenery systems for such projects as the San Francisco Opera House and Canada's Molson Center (JR Clancy) and Cirque du Soleil's Mystère (Show Tech), Lindauer also spent three years as technical director and lighting designer for Celebrity Cruises' fleet ships while running the commissioning of all broadcast and entertainment systems on the Century class cruise ships.
The rise in the number of new cruise ships has prompted many manufacturers to up the ante on designing new products specifically for that market. Stage Technologies, best known for its automation systems on London's West End shows, has adapted some of its technology for use onboard the new generation of mega-cruise ships where well-equipped theatres with automated stage machinery have become the norm.
“On a ship, gravity is not always in the same direction, or equal to 1G, and hence special precautions must be taken,” explains Stage Technologies' Matthew Tonks. “If left to hang freely, scenery will swing as a result of the ship's motion and will soon smash itself to bits. Several ships have solved this problem by using a simple guiding system comprising a blade fixed to the scenic piece running in a fixed guide channel. Because the guides cannot normally be run down to the stage floor, this approach does not work if the flying bar is lowered below its normal operating dead in order to change the scenic piece or for maintenance. Stage Technologies has developed its TanJent guiding system, which allows a flying bar to be positively guided throughout the full length of its travel.”
In addition, Stage Technologies' BigTow has been a workhorse in the theatre; the company has used the same design principles to develop a winch for use onboard ships. The winch uses permanent magnet servomotor and patented zero fleet angle technology, and is mounted in the stage wings onboard, since there is no space for a separate motor room.
The work seems to be paying off. To date Stage Technologies has provided the control systems for nine cruise ships, including the original Grand Princess and ships for Carnival Cruise Lines and Star Cruises. The company has also recently completed the installation of both control and flying systems for Star Princess and currently has orders for similar systems on vessels in the French Chantiers de L'Atlantique shipyards, where Stage Technologies is a subcontractor to Harbour Marine Systems (HMS). In addition, they have orders for control systems on more Carnival Destiny class ships in conjunction with HMS and Star class ships for Wagner Biro.
Last year Stage Technologies was awarded the contract for the supply of rigging systems for the latest of the Grand class ships currently being built for P&O Princess Cruises by Mitsubishi Heavy Industries (MHI) in Nagasaki, Japan. Stage Technologies' scope of supply includes over 60 axes of automation, both mechanical and electrical systems, installed in each of the ships' two venues.