Small Waterplane Area Research Articles

A COMPARISON OF SEVERAL HYBRID SURFACE SHIP CONCEPTS

ABSTRACTIn this paper several hybrid surface ship concepts are described and their estimated speed—power and range performance compared under calm and rough water conditions. The concepts analyzed are the Small Waterplane Area Single Hull (SWASH) Ship, Hydrofoil Small Waterplane Area Ship (HYSWAS), Large Hydrofoil Hybrid Ship (LAHHS), Hydrofoil Air Cushion Ship (HYACS), and Small Waterplane Area Air Cushion Ship (SWAACS). All concepts investigated are of 2,000–ton (2,032m ton) displacement having various combinations of buoyancy, foil lift, or powered static lift from an air cushion.Analysis showed that HYSWAS and LAHHS with about 70% buoyant lift and 30% dynamic lift are expected to have generally favorable characteristics in both calm and rough water over a broad speed spectrum leading to relatively good speed and range performance. These concepts, therefore, appear to be promising configurations for future consideration. However, for special purpose missions where, for instance, only a segment of speed spectrum is dominant or rough water operations are not anticipated, other hybrid forms may show potential and might be pursued further.

Design and Development of the 190-Ton Stable Semisubmerged Platform (SSP)

The general characteristics, design features, predicted performance, and construction highlights of the 190-ton Stable Semisubmerged Platform (SSP) are presented. The SSP is the first large manned version of a high-speed displacement craft concept having a small waterplane area. The SSP was designed to be a work platform for research and testing of advanced naval equipment at the Naval Undersea Center. Its unique design will provide an order-of magnitude improvement in motion reduction over monohulls, as well as provide more deck space and internal volume. The SSP is 89 feet long and has a top operating speed of 25 knots with about 25 tons of payload and fuel. Design of the SSP features two parallel torpedo-like hulls which support an above-water cross structure by means of four vertical surface-piercing struts; two canard fins are located near the hull bows and a cross stabilizing fin is located near the hull sterns. The SSP was constructed at the Coast Guard Shipyard at Curtis Bay, Md.

SMALL PROTOTYPES OF SHIPS—THEORY AND A PRACTICAL EXAMPLE

ABSTRACTTo further the development of an out‐of‐the ordinary type ship, the Small Waterplane Area Twin Hull Ship (SWATHS), a small‐scale prototype, was built and tested. The purpose of this paper is to explain what has been accomplished by the construction and operation of this particular prototype, and, more generally, the purpose to be served by such prototypes.The question arises: Why is the conventional displacement ship so resistant to fundamental change? The hypothesis is advanced and supported that ship design relies heavily on experience, despite scientific advances which tend to give the opposite impression. When a ship is built that goes far beyond the existing experience base, something unexpected ordinarily happens, and ordinarily IT IS BAD. The small prototype provides the first direct experience with the new type of ship. This experience guides subsequent engineering development and the design of the first full‐scale ship. The prototype also can be used to acquaint the first ship's prospective crew with the unfamiliar handling qualities of the new type.Such a prototype of the Small Waterplane Area Twin Hull Ship is described and discussed. Described is the behavior of this craft together with the lessons drawn from it and the modification that had to be made. The relations between small‐scale and full‐scale behavior also are discussed.