A. Ship Design 



Wind-generated ocean surface waves produce 

 the major strains on a ship, and the wave spectrum 

 must be considered in design. Waves cause heavy 

 slamming and propeller emergence that produces 

 dangerous vibrations, and they are of basic im- 

 portance in designing for freeboard, stabUity, and 

 hull strength. 



Loss of speed in heavy weather is a major factor 

 in fuel consumption and power requirements. 

 Better statistical descriptions of ocean wave prop- 

 erties are essential to design ships with higher 

 payload/weight ratios and narrower tolerances. At 

 present, this statistical information is not adequate 

 as a yardstick by which to measure the degree to 

 which test and model basins simulate the real 

 ocean. 



Recent reductions in new ship costs per cargo 

 ton have been achieved by improvements in ship 

 machinery and construction technology, but 

 further reductions seem possible through improved 

 design, resulting from increased understanding of 

 the ship's physical enviroiunent. 



In addition to the savings that could be effected 

 by improving the design of conventional ships, 

 radical departures in design now on the horizon, 

 such as hovercraft, hydrofoils, and cargo-carrying 

 submarines, will require improved and specialized 

 environmental predictions. The impact loading on 

 a hovercraft due to wave action is a major design 

 factor; hovercraft on long voyages will require 

 specialized routings to avoid strong winds and high 

 waves. 



B. Minimum Time Paths 



The abihty to forecast the propagation and 

 decay of ocean waves is limited by the lack of 

 theory-observation feedback. Increased data would 

 enable the scientists to advance their theories and 

 test them more adequately. Even with our present 

 understanding of ocean wave phenomena, it is 

 possible to predict the sea surface conditions to be 

 encountered by a ship along any given route. Ships 

 can be routed along a nunimum time track, or 

 routed for maximum comfort or safety. Such a 

 program is now conducted by the Navy, as well as 

 in other countries, on the basis of available data. 

 Several commercial operators also use least-time 

 track forecasts, usually prepared by private fore- 

 casting services. 



Especially needed to improve these techniques 

 are better knowledge of winds and currents near 

 the sea surface, improved understanding of the 

 generation, propagation, and decay of ocean sur- 

 face waves, and the effects of waves on ships. 



It is not yet feasible to estimate the overall 

 potential savings to the maritime industry from a 

 perfected ship routing program. From data cover- 

 ing MSTS ship routings during 1958, analyzed by 

 the Naval Oceanographic Office, it was estimated 

 that an average of at least $3,000 was saved per 

 ship-crossing of the North Atlantic and North 

 Pacific, due to a reduction of at-sea time.' In 

 addition to time saved, there is a potential saving 

 in improved ship routing by reducing storm 

 damage to ships and cargo. The provision of 

 ship-routing forecasts to commercial shipping lines 

 by private consultants is further indication that 

 the technique is economically worthwhile. 



In addition to ships there are a growing number 

 of stationary platforms at sea— oil-drilling rigs on 

 the Continental Shelf are a prime example. Opera- 

 tion of such platforms requires improved forecasts 

 of environmental parameters. Under certain con- 

 ditions, the working crews aboard the platforms 

 are removed; longer range, and more accurate 

 predictions of those parameters associated with 

 the decision to halt operations would provide a 

 considerable dollar benefit to the operators. 



III. LONG-RANGE WEATHER FORECASTING 



A significant improvement in long-range 

 weather forecasting requires improved understand- 

 ing of the large-scale interactions between the 

 oceans and the atmosphere. Such studies are 

 presently hampered by a lack of data. Present 

 long-range forecasting accuracy is fairly low, but it 

 is clear that considerable economic benefit would 

 result from any significant improvement in this 

 capability. Several examples are: timing the plant- 

 ing and harvesting of crops; planning seasonal fuel 

 transportation and storage, timing road construc- 

 tion, and flood and drought prediction. 



Flood damage could be reduced by manage- 

 ment of flood control structures, for example, by 

 lowering the water levels in reservoirs prior to 

 periods of heavy precipitation or snow melt. The 



^Anon., How Optimum Routing Saves Shipper 

 Services Millions, MSTS Magazine, Vol. 9, No. 11, 

 November 1959, pp. 14-16. 



11-64 



