Nuclear-powered ships also lack the hot exhaust gasses that contribute to the infrared detectability of fossil-fueled ships. Since this was a "quick look" study that excluded or made simplifying assumptions about certain factors, a more comprehensive analysis might be required to decide whether to shift from fossil-fueled large-deck amphibious assault ships or large surface combatants to nuclear-powered versions of these ships. The results of the quick look study, however, suggest that the option may be worth further exploration, at least for the large-deck amphibious assault ships.
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It may also be worth exploring the option for large surface combatants, particularly if oil prices are expected to rise from current levels, and if the operational advantages of nuclear propulsion are also taken into account. Past Nuclear Ships Other than Carriers and Submarines The Navy has not previously built nuclear-powered large-deck amphibious assault ships. Another option would be to design a new plant specifically for this type of hull.
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Bethlehem Steel, Quincy, MA. Procurement of nuclear-powered cruisers was halted after FY due largely to a desire to constrain the procurement costs of future cruisers.
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In deciding in the late s on the design for the new cruiser that would carry the Aegis defense system, two nuclear-powered Aegis-equipped options -- a 17,ton nuclear- powered strike cruiser CSGN and a 12,ton derivative of the CGN class design -- were rejected in favor of the option of placing the Aegis system onto the smaller, conventionally powered hull developed for the Spruance DD class destroyer. The first Aegis cruiser was procured in FY Naval Reactors also states that the additional work in building nuclear-propulsion components could help stabilize the nuclear-propulsion component industrial base by providing extra work to certain component makers whose business situation is somewhat fragile.
These yards, however, are not certified to build nuclear-powered ships. Shifting amphibious assault ships or large surface combatants from fossil-fuel propulsion to nuclear-propulsion might therefore shift at least some of the construction work for these ships away from these yards and toward one or both of the nuclear-construction yards. Naval Reactors is currently uncertain whether final assembly would occur at NGNN or at the yard that built the non-nuclear portions of the ship.
Implications for Port Calls and Forward Homeporting Shifting large-deck amphibious assault ships or large surface combatants from fossil-fuel propulsion to nuclear-propulsion might make them potentially less welcome in the ports of countries with strong anti-nuclear sentiments.
The Navy works to minimize this issue in connection with its CVNs and SSNs, and these ships make calls at numerous foreign ports each year. Given their occasional need for access to nuclear-qualified maintenance facilities, shifting large-deck amphibious assault ships or large surface combatants from fossil-fuel propulsion to nuclear- propulsion might reduce the number of potentially suitable locations for forward- homeporting the ships, should the Navy decide that forward homeporting them would be desirable for purposes of shortening transit times to and from operating areas.
In light of this decision, Yokosuka might be suitable as a potential forward homeporting location for nuclear- powered amphibious assault ships or surface combatants. Sails and Wingsails Sails on masts include both traditional sails and wingsails, which are airfoil-like structures that are similar to airplane wings that have been stood on end. A November magazine editorial notes that: In the late s and early s, huge oil price hikes stimulated much interest in wind-assistance for merchant ships, and several interesting vessels were built from new or converted.
In Denmark, Knud E Hansen has designed a 50,dwt-class bulk carrier, and today in Germany, more research is being handled by Sail Log into a 50,dwt Panamax bulker with 20,m 2 of sail. Traditional square rigs have been chosen by this company because they are known to work satisfactorily, but alternatives do exist, including the more revolutionary Walker Wingsail [ Figure 6 ]. The long-haul bulk trades traditionally not in need of express service have been identified by the German team as most suitable for sail assistance, or even full sail, because the principal bulk trades run more or less in a north-south direction in parallel with the globe's principal wind systems.
Sail Log is part of Schwab-Orga GmbH, which holds the patent to a modern square-rigged design with automated sails Sail Log estimates that sails could normally be used for two-thirds of a voyage. A model has been built and has confirmed all propulsive predictions. Due to low fuel costs at the time and limits on usable wind in the ship's trading routes, Cooke, states, the firm that operated the ship decided that wingsail did not meet the firm's payback criteria. Conventional research vessel cruise planning leads to wind statistics which are favorable to sail assist. A square foot wing sail retrofit to the KNORR would save 90 LT of fuel per year, and would not interfere with mission performance.
Greater fuel savings would result for voyage scenarios with more time in transit. Potential benefits to oceanographic operations include increased fuel endurance, quiet propulsion, improved station keeping, motion reduction, and schedule reliability. In response, the firm between and developed a concept, called Modern Windship, for a meter foot , 50,ton, sail-assisted dwt product carrier. The design is shown in Figure 7. Figure 7. The impact of variations in fuel prices was stressed.
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The effect of varying the average speed was investigated. A product carrier was chosen as study example. The study pointed out some of the commercial limitations of WindShip-application at present time.
It proved uneconomical to use WindShips on typical product carrier routes. However, by adding the rig of the WindShip on average an additional three tons of fuel per 24 hrs could be saved in the more windy areas. On the economical side the results may be less inspiring at first sight. There is no doubt that the results were both reliable and realistic. However, the main conclusion that emerged was that a product carrier is not the preferred choice for a modern WindShip.
Worse yet, the fuel savings were marginal, under certain assumptions and conditions a WindShip even consumed more fuel than a conventional ship. Decisions on sail area etc. At the same time the feasibility study showed that the comparison had been made at a sub-optimal speed for a WindShip.
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Due to the special requirements of the product carrier trade the larger internal volume of a WindShip was not used to its advantage in the study. Taking the above issues into account we see the potential of modern WindShips concept. If speed is reduced, but same productivity is maintained due to the larger volumes carried, money will be saved. It is in this market segment that the WindShip should operate. Careful routing, including effects of seasonal weather variations could then prove the WindShip both environmentally beneficial and economically favourable.
One article states: In unfavourable winds, large masts create a lot of drag. In gales, masts cause ships to heel, sometimes dangerously.
Masts and their pivoting sails take up valuable container space on the deck. Loading and unloading is more expensive, since the cranes that lift containers must work around the masts. Engineers designed taller and more expensive masts, some exceeding metres in height, to reduce their number and limit the loss of storage space. But the Panama Canal limits masts to 60 metres, and collapsable masts would be prohibitively expensive to build, operate and service So the sails would have taken around 15 years to recoup their costs through fuel savings.
At least two firms -- the U. The industry has done this before, and will do so again. These worldwide economic and political conditions are upon us today. This time, there is strong evidence that recent fuel cost increases aren't going to be temporary, and environmental restrictions will become increasingly draconian. Conventional masted sail solutions have inherent limitations which will continue to delay their application long past the point where wind-assist can become cost effective.
The ability to design massive sail power without need for ballast, without fixed masts interfering with loading and unloading procedures, without adding hundreds of tons and tens of millions of dollars to build costs is critical. The ability to retrofit existing vessels cheaply and efficiently is paramount. The ability to build, repair and maintain systems remote from shipboard, eliminating downtime is an important asset; KiteShip has understood these advantages for decades.
We have been readying appropriate technology for commercial tethered flight sailing since KiteShip Concept Applied to Commercial Cargo Ship One of the principals of Kiteship, Dave Culp, stated in a interview: In studying attempts to bring back commercial sailing ships in the 's, it struck me that they were doomed to fail for the same reasons commercial sail failed in the 19th century.
The cost of the equipment, expressed as a rate of amortization, was far higher than powered vessels, even including their fuel. Second, the fundamental inability to schedule wind power plays havoc with effectively utilizing expensive ships. Motor sailing was and is possible to fix this, but requires parallel systems on the boat -- wind plus diesel -- at even higher total cost. Kites, on the other hand, can be added to existing ships. They take up no deck space, require minimal retro-fitting, need no ballast, fit under bridges and can be taken in out of the weather when not in use.
These factors dramatically decrease the capital cost of the sailing rig, thus the amortization rate. If added to existing vessels, especially if the vessels are partially depreciated already, it becomes very cost effective to fit a single ship with both power which it has and kites which are cheap. It can then pure sail, motor sail or straight motor, as conditions dictate. The intent is to showcase environmentally friendly fuel[-]saving technology, further develop kites and control systems for ever[-]larger applications, and to demonstrate to Adventure Spa Cruise customers a proactive stance regarding potential near-term fuel price spikes and shortages.
Ford CVN class carriers. The Navy made the announcement on the same day that it deactivated the year-old aircraft carrier CVN, also named Enterprise. If CVN, like most Navy ships, had been named at about the time of procurement, or later, rather than in , it would have been named by the current Secretary of the Navy, Richard Spencer. First, it will allow a future Secretary to name a future fleet aircraft carrier for someone or something other than a former President.
Indeed, Secretary Mabus has a particular name in mind. Secretary Mabus believes this circumstance could be remedied by bestowing the Enterprise's storied name on a future carrier. Destroyers traditionally have been named for famous U. The July Navy report to Congress discusses this tradition and states more specifically that destroyers are being named for deceased members of the Navy, Marine Corps, and Coast Guard, including Secretaries of the Navy.
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