Follow the usual rules -- and many more when your site is on the waves

By DOUG DIXON
Guido Perla and Associates

Imagine you were designing Columbia Seafirst Center, but you had to make it self-contained - making its own electricity, freshwater and treating its own sewage. Now imagine laying the building on its side and adding engines to make it move while trying to keep it from rolling and vibrating from the force equivalent to a continuous earthquake. When you are finished with the design, you get to do a second set of calculations to move it from land and launch it in water. That's what naval architecture is all about.

Naval architects go through the same level of architectural training as their land-based counterparts with more emphasis on structural, mechanical and electrical engineering. Added to this is the application of hydrostatic and hydrodynamic principles, all carried out using state-of-the-art computer programming. The State of Washington has a professional engineering registration system governing these activities under the same rules as land-based architects and engineers.

The 360-foot, 3,000-passenger Majestic Star casino vessel designed by Guido Perla & Associates in Seattle.

Arrangement of the living, working and support space is sometimes more critical in naval architecture. Real estate is very expensive, because the naval architect has to create it. Imagine building a structure on an island, but first having to build the island. It is a space utilization challenge to make a comfortable, livable environment that is streamlined for efficiency but not too large to impact cost. The design must then have enough shape for "seakindliness" - to produce reduced, livable motions - and enough flare to repel heavy seas.

The standard Uniform Build-ing Code is replaced by use of U.S. Coast Guard regulations and Classification Society rules such as the American Bureau of Shipping, Lloyd's Register, Det Norske Veritas or French Bureau Veritas. References are still made to national and international building codes that keep a measure of uniformity between the land and water rules, but sometimes are at odds with international regulations. Typical seismic structural analysis and AISC rules are also in the naval architect's tool kit. Rules for egress, safe refuge areas, main vertical zones, stair towers and passageway arrangements for fire safety occupy many hours of engineering, customer interface and regulatory submittal time when designing a new vessel. Safety and lifesaving provisions must be made to safeguard passengers and crew from the perils of the sea.

Design and construction of the structure must be arranged to accommodate the fact that a vessel is moving. Standard landside building design and structural criteria cannot be used. Poured concrete slab floors pose design and construction challenges on floating, moving structures. Interior structure and outfitting must also be designed to accommodate racking and shock loads from motion in the sea and unintended hard landings. Naval architects must consider accelerations and energy data when sizing structure, but must keep weights under control, not just for cost consideration, but stability of the vessel.

Imagine laying Columbia Seafirst Center on its side and adding engines to make it move while trying to keep it from rolling and vibrating from the force equivalent to a continuous earthquake.

Mechanical systems also need a marine perspective to ensure proper support and operation, i.e. foundations, pipe hangers and drainage in heeled conditions. Elaborate ballast pumping systems are required to compensate for varying load distributions.

The harsh seawater environment becomes another critical element in the material selection process.

A complete electrical generation and distribution system design is required. Electrical integration of load, voltage drop, short circuit analysis, preferential trip and harmonics are necessary between all of the systems such as propulsion, hotel and vital vessel systems. In addition, extensive alarms are required, not just for fire detection, but all critical systems that support the vessel. Loss of a system such as electricity in a building can be unpleasant and force everyone to leave. That same loss on a vessel in heavy seas could result in engine, pump or control failure with resultant loss of the entire vessel and everyone on board.

History and the failures of vessels over time have contributed to the evolution of naval architecture. Notable catastrophes like Titanic and Estonia have spurred the United Nations' to enact regulations and strengthen them after major disasters. However, it has been through forensic failure analysis that real technical advances have been made. An example is the increased awareness of the brittle fracture energy characteristics of steel as temperature declines. Varying impact resistance was discovered long ago with rules generated to set standards, unfortunately too late for the lost souls of the Titanic.

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