Techniques and procedures are well established for the reliable sizing and analysis of conventional monoblock propellers on powered vessels, such as motor yachts and other pleasure craft. However, the use of these propeller sizing criteria and analysis techniques have proven ineffective for auxiliary-powered sailboats with folding propellers. This paper is intended to be a “design guide” for the sizing and analysis of folding propellers on auxiliary powered sailboats, utilizing both anecdotal evidence and analytical investigation in the development of new criteria and recommended procedures. Topics considered in this paper include speed prediction, calculation models for folding propellers, and cavitation criteria.

Much of the literature available for the computerized prediction of ship performance is devoted to the equations and formula that mathematically represent model test results. It is not the intent of this paper to reiterate this body of work, but rather to provide background and guidance to designers regarding the confident application of these numerical methods through the use of commercially or individually developed personal computer software. The paper covers these issues by reviewing basic methodologies for the prediction of resistance and propulsive coefficients; by introducing various numerical formula and data; by describing techniques to correlate predicted results with known performance; and by presenting a systematic approach to predicting the various aspects of a vessel's performance with personal computer software.

A widely used technique to correct and enhance vessel performance is the propeller "cup" - a curvature applied to the trailing edge of a propeller blade. Although cupping has become a regular procedure in small propeller shops, it is typically applied without any systematic rules or quantifiable understanding of its effect on performance. The traditional definitions of cup (e.g., light, heavy) vary greatly from one company to the next, and even from one project to the next within the same company. It is the goal of this paper to provide a consistent definition of cup geometry for practical use in industry, as well as a new performance model that can be used in propeller calculations.

The Series 64 has been an oft-cited resource for the resistance prediction of high-speed transom-stern round-bilge hull forms since publication of Yeh’s paper (1965). Its range of parameters is extensive, making it one of only a few sets of test data for long and slender hulls. In the course of this author’s planned development of a computational prediction model based on the Series 64 data, significant outliers in the expected series family of curves were revealed and it became evident that there were inconsistencies in the relative relationships between hulls in the series. This prompted a re-analysis of the series to identify potentially erroneous test results and conclusions in the original work, so as to remove them from the numerical data set for a proposed computational model.

The maritime industry is in a mind-set to save fuel and reduce emissions. How one achieves this end, however, can be a matter of some debate. Although substantial industry effort is being placed on things that can be optimized, to achieve real benefit and financial return one must first understand the details about how the vessel consumes propulsive energy during its mission. This article discusses a rational, simple, and effective systems engineering approach to identify power and fuel demands via computational propulsion analysis of the individual operating modes of a vessel's duty cycle. It explains sensible consumption metrics that can be used to evaluate and compare different physical systems, strategic plans, or helm decisions. A duty cycle operating mode analysis calculation for a tugboat in multirole service (as a harbor tug and in long haul ocean barge towing) is demonstrated using commercial off-the-shelf software, including examples of design-side and shipboard decision options and consequences.