Experimental Investigation into the Resistance Characteristics of Trimaran and Pentamaran Configurations

Research on the development of multihull vessels has investigated the breakdown of trimaran side hulls and produced a new type of vessel popularly known as a pentamaran. This study into the resistance characteristics of pentamarans was carried out using a towing tank belonging to the Institute Technology at Sepuluh Nopember in Surabaya, Indonesia. A test of trimaran resistance was included for comparison. The investigation focused on total resistance estimation and interference analysis for the two types of multihull vessels at separation–length ratios (S/Ls) of 0.2, 0.3, and 0.4. The dominant resistance value for the pentamaran was higher than that for the trimaran, with an average of 5.2%, due to the more complex interference between hulls. The average total resistance interference was 9.5% for the trimaran and 12.5% for the pentamaran.

Experimental study; Pentamaran; Resistance; S/L ratio; Trimaran

The use of multihull ships as passenger carriers has been common for the last 50 years, according to Insel and Molland (1992). Multihull vessels are more stable than single-hull vessels (Peng, 2001) and can provide larger deck areas than single-hull ships of the same length (Molland and Utama, 2002), (Samuel et al. 2015). Sahoo et al. (2007) reported that multihulls are safer than their monohull counterparts because of their greater and more easily maintainable transverse stability as well as their larger above-water capacities. The most interesting phenomenon is its ability to reduce wave-making resistance based on adjustments to the hull configuration and hull form (Iqbal and Samuel, 2017).

Most multihull ships are more seaworthy than their monohull counterparts, and ships with short waterplane areas exhibit high-performance seakeeping characteristics. The strength specificity of multihulls plays a vital role in defining transverse loads and preventing wet-bottom slamming in multihull vessels (Dubrovsky, 2009). A trimaran is a multihull vessel that consists of one main hull and two side-hulls, which are known as outriggers. The side hulls are smaller in size and positioned on either side of the main hull. Trimaran hulls are an advance on single hulls, intended to enhance a ship’s speed while simultaneously reducing power requirements (Tupan and Luhulima, 2020). The increased allowable aspect ratio of these hulls makes them more energy efficient when operating at high speeds (Utama et al. 2021a).

The unique hull shape was designed by Nigel Gee and Associates Ltd. In the United Kingdom (Gee et al. 1997). The pentamaran is a slender, stabilized monohull that, compared to conventional monohull or catamaran designs, has the potential to reduce power consumption by up to 30 % for large high-speed vessels. Ikeda et al. (2005) found that a pentamaran ferry outperformed a monohull ferry in terms of performance, dead weight, and deck area. The results suggested that, from an economic standpoint, pentamaran passenger ferries could replace monohull roll on/roll off (ro-ro) passenger ferries. 

A ship’s side hull is designed to meet certain stability standards (Luhulima et al. 2014). The use of four side hulls on a pentamaran can enhance stability for the rolling motion and ensure minimal resistance. Pentamaran ships offer the reduced resistance and maximized power needed to drive ships forward while maintaining high seakeeping qualities (Gee and Hawkins, 2005). A pentamaran is a monohull vessel that is stabilized by four side hulls—two on the starboard side and two on the port side. A ship’s main hull is designed to have the lowest feasible resistance for a given displacement and speed (Sulistyawati et al. 2019).

Research on the resistance properties of trimarans and pentamarans relative to the interference effect is incomplete due to the large number of potential configurations for this type of vessel. The topic of trimaran hulls has attracted significant worldwide research attention and led to the possibility of unconventional maritime vehicles. A recent study proposed a pentamaran hull for passenger and vehicular transportation (Gee and Hawkins, 2005); however, published articles (Gee et al. 1997) regarding pentamarans provide little information about their hydrodynamic behavior in terms of resistance, which is vital for ensuring ships’ hydrodynamic performance. because it is tied to ships’ hydrodynamics. Pentamarans have interesting potential as water transportation vessels with slim hulls and long ship dimensions of mainhull. Each side hull supports both front and rear stability; hence, the most recent studies (Yanuar and Waskito, 2017) comparing trimaran and pentamaran vessel designs have focused on achieving optimal resistance characteristics across a range of speeds. Further investigation could provide a precise explanation for the related interference phenomena, which can affect vessel performance in certain cases. The present research on trimaran and pentamaran vessels considered lateral spacing and longitudinal side hulls. The scope of the study was limited to model resistance characteristics and the interference factor (IF) values for a specified Froude number (Fr) range (i.e., from low to moderate). These two types of resistance were considered essential among the various resistance components because interference phenomena impact both the wave-making resistance and viscous resistance of multihull vessels. This article provides an overview of the findings. 

    The current study made fairly good predictions of resistance according to the provisions of the ITTC procedure. The resistance testing was carried out using two types of multihull vessels (a trimaran and a pentamaran) with variations of Fr and S/L. Several notable results were obtained from the series of experiments. Both multihull vessels with variation S/L = 0.2 had greater resistance than other variation models. The difference was quite significant between the individual and combined hulls with a variation of S/L = 0.2 (i.e., an average of 16.2% for the trimaran and 15.9% for the pentamaran). The trimaran model’s interference was significant at Fr = 0.5, whereas interference for the pentamaran model occurred at Fr = 0.3. The pentamaran’s dominant resistance value was greater than that of the trimaran due to the more complex interactions between the hulls.

    A benchmark uncertainty analysis for an experimental test of Trimaran Model A was carried out for Fr = 0.2–0.6 and demonstrated reasonable agreement. The uncertainty values for the variables that affected the test results revealed uncertainty values for five variables that were the source of experimental errors: wet surface, speed, temperature, and single test. Quantitative analysis gave the highest uncertainty value of 0.478% for a single test component and 0.985% for the combined mean. The smallest uncertainty value was for the temperature component.

    The authors gratefully acknowledge financial support from the Institut Teknologi Sepuluh Nopember for this work, under project scheme of the Publication Writing and IPR Incentive Program (PPHKI) No. T/2029/IT2/HK.00.01/2021.

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