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

Abstract

) 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...

Archaic Ship Graffiti from Southern Attica, Greece: typology and preliminary contextual analysis

“…539). A cutwater would have much improved the hull's hydrodynamics and speed, as has recently been demonstrated through a tow‐tank experiment with the model of an ancient Greek warship with a waterline ram serving as a cutwater (Murray et al ., ).…”

Numerical Reconstruction in Maritime Archaeology

“…Murray et al [61] performed an experimental investigation of the origin and development of the waterline ram. The Trireme Trust's 1:20 scale model of Olympias was fitted with two different bow types: (a) a control bow and (b) a cutter bow, (Figure 23).…”

Comparison of Different Methods for Ancient Ship Calm Water Resistance Estimation

“…The most straightforward example of applying modern technologies for assessing old vessel hydrodynamic properties was completed by Murray et al [4], where experimental towing tank tests were performed so the origin and development of the waterline ram could be investigated. By using towing tank testing, the authors supported their suspicion that bow projection was not just developed as an offensive weapon but also functioned as cutwater and thus, increased hull speed.…”