The Social History of the Bulbous Bow

Ferreiro, Larrie D.

doi:10.1353/tech.2011.0055

Cited by 7 publications

(7 citation statements)

References 23 publications

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“…7), significantly reduced the wave profile generated by the hull, thus lowering wave-making resistance. A similar mechanism is evident in modern ships having a bulbous bow (Ferreiro, 2011), but there is an important difference: while an underwater bulb creates a wave opposite to the control bow wave, providing some wave cancellation (and thus a reduction in wave resistance), the cutwater appears to be creating a complex wave system that interferes with, and reduces, hull wavemaking resistance. As noted, a rockered keel would provide the upward curve as it projected past the stem area.…”

Section: Discussionmentioning

confidence: 84%

Cutwaters Before Rams: an experimental investigation into the origins and development of the waterline ram

Murray

Ferreiro

Vardalas

et al. 2016

International Journal of Nautical Archaeology

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) investigated the reasons for an elongated projection at the bow of Mediterranean galleys. Using a 1:20 base model adapted from the Trireme Trust's Olympias fitted with: 1) an elongated projection; and 2) a control bow similar to excavated merchant ships, tow-tank tests were carried out at various speeds. Hydrodynamic resistance and power were calculated for each bow type. Above speeds corresponding to 6 knots, the cutwater bow significantly attenuated the model's bow waves when compared to the control bow. These results were then compared to those of the ship with a ram-type bow from experiments conducted in 1985 at the National Technical University of Athens, which showed similar wave-attenuating characteristics. © 2016 The AuthorsKey words: cutwater, ram, bow, galley, trireme, hydrodynamics.I n 2014, Michael Geselowitz and John Vardalas (of the IEEE History Center) piloted a new kind of humanities course at the Stevens Institute of Technology (SIT). The course 'Engineering in History', a survey of engineering from prehistory to the 17th century of our era, aimed to marry hands-on laboratory classes with traditional history lectures. Vardalas encouraged his students to explore the design and use of technology in problem-solving scenarios in different historical contexts. Vardalas, who has a special interest in maritime history, wanted to design a term project around the theme of ancient vessels, a choice that was influenced by the world-class facilities in marine engineering and naval architecture at Stevens. He accordingly contacted Larrie Ferreiro, who involved William Murray, who in turn asked Jeffrey Royal to collaborate. A few conference calls and a quick exchange of emails convinced us all that the class might usefully study a long-standing question in Mediterranean ship design: the introduction of the ram/cutwater bow on long, narrow Mediterranean galleys.Students in the class were broken into two teams: one testing a vessel with an ancient cutwater design, the other testing the same hull but with a more conventional-looking bow. Hull lines were based on Olympias, the famous trireme designed by J. F. Coates and J. S. Morrison, built by the Hellenic Navy, and launched in 1987 (Morrison and Coates, 1989;Morrison et al., 2000). We freely acknowledge the methodological problems involved with using these lines, which Coates developed specifically to merge with a ram prow. Nevertheless, considering the constraints placed on us by the timing of the course exercise, we felt they provided a good starting point for our test. These lines had the additional advantage of being made immediately available to us (both drawings and offsets) by the Trireme Trust, whom we wish to W. M. MURRAY ET AL.: AN EXPERIMENT IN ANCIENT CUTWATER HYDROGRAPHICSthank. Without this information, it would have been impossible to produce our 3D hull models in time for the scheduled tests. Based on ancient ship iconography and knowledge of ancient ship construction, the authors also produced a cutwater design that was then given to the Dav...

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Section: Discussionmentioning

confidence: 84%

Cutwaters Before Rams: an experimental investigation into the origins and development of the waterline ram

Murray

Ferreiro

Vardalas

et al. 2016

International Journal of Nautical Archaeology

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“…where L is the length of the ship. In our problem, the reference length is obviously √ a, so it is more natural to define the Froude number as in (20), that is…”

Section: 3mentioning

confidence: 99%

“…The numerical simulations in [18,31,35] showed that the famous bulbous bow [20,26] can be very efficient in minimizing the total resistance, for some values of the parameters. In some cases, a midship bulb was also found to be interesting [15,23,30,31].…”

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confidence: 99%

Continuity with respect to the speed for optimal ship forms based on Michell's formula

Dambrine¹,

Pierre²

2023

MCRF

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<p style='text-indent:20px;'>We consider a ship hull design problem based on Michell's wave resistance. The half hull is represented by a nonnegative function and we seek the function whose domain of definition has a given area and which minimizes the total resistance for a given speed and a given volume. We show that the optimal hull depends only on two parameters without dimension, the viscous drag coefficient and the Froude number of the area of the support. We prove that, up to uniqueness, the optimal hull depends continuously on these two parameters. Moreover, the contribution of Michell's wave resistance vanishes as either the Froude number or the drag coefficient goes to infinity. Numerical simulations confirm the theoretical results for large Froude numbers. For Froude numbers typically smaller than <inline-formula><tex-math id="M1">\begin{document}$ 1 $\end{document}</tex-math></inline-formula>, the famous bulbous bow is numerically recovered. For intermediate Froude numbers, a "sinking" phenomenon occurs. It can be related to the nonexistence of a minimizer.</p>

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“…Assuming the vessel maintains a consistent speed, an appropriate bulbous bow design can lead to favorable interference between the bow waves generated by the bulb and those generated by the hull alone. According to [6,7], this can lead to a decrease in resistance of between 12% and 15%. Other types of bows, such as dihedral bulbous bows, have been confirmed in [8,9] as good alternatives for ship resistance.…”

Section: Introductionmentioning

confidence: 99%

Fishing Vessel Bulbous Bow Hydrodynamics—A Numerical Reverse Design Approach

Díaz Ojeda,

Oyuela,

Sosa

et al. 2024

JMSE

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Naval hydrodynamics typically focus on reducing ship resistance, which can be achieved by incorporating a bulbous bow. This feature is commonly used in the merchant fleet and smaller vessels, such as fishing boats, to minimize wave-making resistance. However, it is important to note that the use of a bulbous bow may not always be necessary or effective in all ship designs. In some cases, fishing ship designs may include a bulbous bow that is not optimized due to the use of procedures and methods intended for larger merchant ships or based on past experience. This study examines the effect of different bow designs, including the bulbous bow, on ship resistance in calm water, with a focus on a typical Argentinian trawler fishing vessel. The objective of this research is to assess the hydrodynamics of various designs for a particular ship by modifying its vessel lines. Firstly, the bulbous bow is removed, and then the reduction in ship resistance achieved by the bulbous bow under different load conditions and speeds is evaluated by comparing the vessel with and without the bulbous bow. The numerical analysis is performed using OpenFOAM, and the results are validated through towing tank experiments. This research indicates that the performance of the bulbous bow varies under different conditions. Therefore, it is recommended to conduct an initial study and a full evaluation of the design and operation alternatives.

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The Social History of the Bulbous Bow

Cited by 7 publications

References 23 publications

Cutwaters Before Rams: an experimental investigation into the origins and development of the waterline ram

Cutwaters Before Rams: an experimental investigation into the origins and development of the waterline ram

Continuity with respect to the speed for optimal ship forms based on Michell's formula

Fishing Vessel Bulbous Bow Hydrodynamics—A Numerical Reverse Design Approach

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