Sea Technology

JUL 2017

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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www.sea-technology.com July 2017 / st 17 T he average person is seemingly tethered to their elec- tronic devices with a near-compulsive need to check email and texts or update social media profiles. Cruise ship lines have responded by investing millions of dollars in in- frastructure to provide wireless Internet access for custom- ers. The irony of going wireless is that the amount of actual wire or cable required to support sophisticated data and communication networks multiplies. Today's cruise ships even incorporate onboard data centers to keep passengers connected. One thing is for certain when it comes to technology, and that is that change is inevitable. As newer technology becomes available, quite often, the network cabling must be modified or replaced. In structured cabling parlance, such modifications are referred to as cable moves, additions or changes, or MAC work. Traditional Cable Transit Systems While new-generation technology platforms trigger MAC work, the one area that has not kept up with the times are the cable transits through which the cables are routed through bulkheads and decks. The most common type of ca- ble transit consists of a steel frame fitted with rubber blocks. Each individual cable is routed through a rubber block and secured within the frame by wedge plates. Often referred to as a multi-cable transit, these devices were first devel- oped for shipboard use in the early 1950s. The designs have been refined many times over the years, and compared to the original devices, the modern versions represent marked improvement. When it comes to the volume of cable required to sup- port today's communications networks, however, these traditional cable transits can be cumbersome. To make a simple cable change requires loosening of the wedge plate assembly and rubber blocks. The new cable has to be rout- ed, and then the blocks and wedge plates need to be reas- sembled and tightened. The problem can be compounded when a greater density of cables is required to be routed through a transit frame than the frame can accommodate. To provide greater flexibility in terms of the cable ar- rangement, some shipyards have replaced the traditional block-and-frame cable transits with welded steel sleeves and flexible sealant systems. Such systems can often increase cable fill percent- age and provide ease of installation. However, they still have limitations in that the liquid- applied sealants cure to a rubber-like consistency and the cables are effectively glued together. While the cured seal can be cut into to add or remove cables, this still requires diligence to reseal the opening to patch or repair the dam- aged seals. New Cable Transit Technology Over the past few years, a new cable transit technology has emerged. These transit devices are purpose-made to handle cables passing through nonwatertight bulkheads and decks that will be subject to frequent moves, additions and changes. The new-generation transits incorporate self-seal- ing foam pads that automatically adjust to the cable load. As cables are inserted, the pads retract, thereby allowing the cables to pass through unchecked. After the cables are in- stalled, the pads rebound to tightly seal around the grouped cables. The soft, supple foam conforms to the cables. In the event of a fire, the pads are intumescent, which means they will expand with heat to form a dense, insulative char that resists passage of flames, hot gases and smoke in accor- dance with IMO FTP requirements. These cable transit devices feature mounting plates that can be welded or screw-attached to bulkheads or decks. Individual cable transits can be ganged together to increase cable capacity. The convenient design of the transits and the associated mounting plates also maximizes the volume of cable that can be installed into a given area, which means the open- ings in the bulkheads or decks can be reduced both in terms of size as well as the number required. New-Generation Cable Transits Accommodate Wireless Internet Modern Cable Transits for Structured Cabling Systems on Cruise Ships By Ruben Wansink • James P. Stahl Traditional multi-cable transit.

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