Table of Contents:
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Canadian
Atlantic |
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New
York Metropolitan |
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Table of Contents:
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New
York Metropolitan Section Meeting
February 12, 2004 - Moran’s Restaurant was the site for the NY Met Section’s February meeting. Stephen Wright of Thomas Electric Control, Inc. gave an interesting and informative presentation on electric propulsion. Steve began the presentation with the interesting fact that propulsion systems are easier than non-propulsion marine applications to design. This is because all of the load conditions for propulsion systems have been thoroughly analyzed. Steve then led the audience in the design process for electric drive selection. The motors used in propulsion are usually custom designed for the individual applications, and are mostly water-cooled to minimize their size (as compared to air-cooled motors). After the type of propulsor has been determined and the decision has been made to use electric propulsion, the first major design decision is whether to use a direct current (DC) or an alternating current (AC) system. Although AC motors and drives are the usual choice, Steve went through several scenarios where DC motors and drives would be the better selection. Retrofitting existing systems, keeping propulsion systems consistent across a given fleet of vessels, minimizing the initial investment on a vessel not intended to be owned for a period of more than five years, and building vessels with strict acoustic limits are applications where DC systems can be the better choice. Steve brought in examples of past jobs accomplished by his company where DC motors and drives were used. The disadvantages of using DC systems were then explained. The primary weakness in DC systems is the amount of maintenance required to keep them operating safely, and the resulting problems, including flashover, that occur when they don’t receive proper maintenance. The advantages of electric propulsion were then discussed. For ships with high hotel loads, stringent maneuverability requirements, or strict redundancy and flexibility requirements, electric propulsion is the system that can best meet the operating specifications. Steve then discussed AC system design, including an in-depth review of the variations in AC drive design. He highlighted the difference in passive and active front-end drive design, and then discussed how to mitigate harmonic problems within AC drives. After discussing impending developments in the electric propulsion field, Steve concluded the presentation and took a few questions from the floor.
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New
England December
18, 2003 The presentation illustrated the types of work that Mr. Hudson is involved with, the equipment used in his one-person office, as well as the software used and its application. Various lofting processes were described, along with design processes, and Mr. Hudson’s project management responsibilities.
Mr. Hudson’s work focuses on lofting, although he is also involved with full design as well as stability analyses, and re-powerings. As such, he utilizes a basic desktop computer system and plotter. Two-dimensional drawings are done using MiscroStation, and three-dimensional surface modeling is accomplished using Multisurf. Mr. Hudson described his experience with efficient use of these technologies and their use in lofting. Mr. Hudson’s design process and typical design spiral were described. Additionally, Mr. Hudson described his experience receiving electronic transmission of photos etc. from his boat builder clients, and subsequently, of the transmission of electronic drawings to his clients, both of which have streamlined the management of his various projects. Oak Hill Marine Design is a full service naval architecture firm located in Southwest Harbor, Maine committed to designing, nearly full-time, boats for Winninghoff Boats, Inc. in Massachusetts.
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