Experimental analysis of the seakeeping performance of catamaran forms with bulbous bows

Abstract

Abstract.This paper explores the effects of adding different forms of bulbous bows onto catamaran hulls and assesses the implications on the seakeeping performance. There has been a large body of work that assess the effect of wave wake wash and recently studies have been undertaken to determine the effects of bulbous bows on reducing wave wake wash. However, not much research has been published on the effects of bulbous bows on the seakeeping performance of catamarans fitted with bulbous bows. This paper presents experimental results that will allow a ship designer to understand the effects of bulbous bows on heave, pitch and added resistance in waves. In conclusion it ranks the importance of different bulbous bows on the seakeeping performance.Keywords. Bulbous bow,seakeeping, added resistance, heave, pitch, waves BackgroundIn recent years fast ferries which are capable of speeds in excess of 40 knots have been operational in water of depth of less than 10m. As high-speed operations near sensitive shorelines increase, complaints from the public on extensive wave wake or wake wash from these fast vessels have increased. Although the leading waves in the wash are very small in terms of wave amplitude compared to storm waves, they have a very long period and build in height rapidly in shallow water at the shoreline, thereby, causing substantial surges on beaches as well as breaching sea walls at high tide. This wake wash is likely to have environmental effects such as shoreline erosion as well as endangering swimmers and small boats. During 1997, as a consequence of public concern, the Danish Maritime Authority issued a governmental order which requires that the high-speed craft operator/owner has to show evidence that the ship-generated waves do not exceed a prescribed wave height criterion in shallow water along the entire route. Similar criteria exist for other regions, such as the Puget Sound, Seattle, some navigable inland waterways in the Netherlands and the River Thames, UK particularly the route between Southampton and the Isle of Wight), Nantucket, the Mare Island Channel and the East Bay Estuary in San Francisco Bay. The main risk to coastal communities and users of the waters in coastal areas is that the waves arrive unexpectedly and break on the shoreline often after the fast ferry is out of sight, Whittaker (2001) [7]. Shallow water dramatically increases the wash. In shallow waters, the seabed interfere with ship wave-making forcing changes to wave patterns, energy levels and vessel running condition.

Seakeeping Prediction of Deep-v High Speed Catamaran Using Computational Fluid Dynamics Approach

“…According to (Grande & Xia, 2002), (Belknap, 2008), (Lin et al, 2017 ) and (Aribenchi, 2017) seakeeping performance was also predicted using strip theory method. Besides that, (Vakilabadi, Khedmati, & Seif, 2014), (Yanuar, Ibadurrahman, Karim, & Ichsan, 2017), (Abdul Ghani & Wilson, 2017) and (Zotti, 2007) studies the behavior of catamaran ship using experimental method approach that have their own disadvantages such as complex procedure, costly and time-consuming. In the other ways, numerical method using Computational Fluid Dynamics (CFD) also offers more easer procedure and accurate data to study hydrodynamics characteristics of 'deep-V' catamaran.…”