© Marine Technology, Vol. 45, No. 4, October 2008, pp. 194–210 Resistance Characteristics of Fishing Boats Series of ITU Muhsin Aydin1 and Aydin Salci2 This paper presents the results of the resistance and propulsion tests carried out during the development of the Fishing Boat Hull Form Series of ITU, providing the means of designing modern fishing boats capable of operating in the Black Sea, Marmara Sea, Aegean Sea, and the Mediterranean Sea. Initially, nine modern hull forms were generated using the hull forms of the traditional Turkish fishing boats. The model resistance tests of these fishing boats were carried out in the lightship, loaded, and highly loaded conditions. In the present paper, these hull forms are introduced, followed by a systematic presentation of comparative results illustrating the scale effects and the extrapolation diagrams, the influence of the block coefficient, the length to beam ratio, the type of stern, the shape of chine and the fore and aft trim on viscous resistance (form factor k), and wave-making resistance (wave-making resistance coefficient CW). The findings on the effects of some appendages such as the rudder, the heel of the rudder and the stern tube on the viscous resistance (form factor k), and the total resistance (total resistance coefficient CTs) are also illustrated. Finally, a general discussion of the results obtained from the resistance tests, wake measurement tests, and flow visualization tests are presented. Keywords: resistance (general); hydrodynamics (hull form); fishing vessels 1. Introduction variables was constituted (Hayes & Engvall 1969), together with a regression equation of 72 terms for a model of length THE FISHING BOAT constitutes the most significant compo- 4.9 m and results of some calculations for various Froude nent of the fishing industry which in turn is an important numbers. Van Oortmerssen obtained frictional and residuary activity in the economies of not only countries at varying resistance values using an algorithm based on 970 measure- stages of development, but also of developed countries. The ments of resistance data from 93 fishing boats, tugs, and hull forms of fishing boats show considerable variation in passenger ships (Van Oortmerssen 1973, Van Oortmerssen various regions of the world, depending on the fishing meth- 1980), where the frictional resistance values were calculated ods, meteorological and geographical conditions, accumu- by the formula of ITTC-57 and the residuary resistance was lated knowledge and experience, and also scientific and tech- calculated through a regression equation having six hull nological development. The common influence observed in all form parameters. Prifti and Grigoropoulos obtained and pre- of these variations originates from the traditional hull forms sented the model resistance data of traditional Greek hull indigenous to a given region. These hull forms require im- forms used widely as fishing boats and passenger ships in provements parallel to the developments in fishing methods, Greek waters (Prifti & Grigoropoulos 1995). Other regression and the model test techniques provide the basis for such un- and comparison studies also exist (Doust et al. 1967, Anto- dertakings. Fishing boats have been studied extensively in niou 1969). various parts of the world. An example of such work is on the The fishing boats of Turkish waters can be classified into resistance characteristics of a trawler having the prismatic three types with respect to their properties: these are the coefficient value of 0.65 (Ridgely-Nevitt 1956). Taking this Taka, Cektirme, and Alametro types. All these traditional hull form as the basis, three trawler hull forms having the fishing boat hulls are hydrodynamically inefficient to various prismatic coefficient values of 0.5, 0.6, and 0.7 were gener- degrees. Their underwater hull forms are inefficient in terms ated and model tests were carried out to obtain the effects of of resistance and propulsion. These hulls have longitudinal various parameters on the resistance characteristics (Ridgely-Nevitt 1963). The following results were obtained: centers of buoyancy situated forward of amidships, the aft the effect of the ratio of beam to draught on resistance is hull form and the propeller housing are not suitable for effi- higher than that of the prismatic coefficient, the transom cient propulsion, and their rudders are ineffective. They do stern and bulbous bow together improve the resistance char- not have enough stern deck area for working and net storage. acteristics at high speeds, and the prismatic coefficient af- In the ship model testing laboratory of ITU Naval Architec- fects resistance significantly. Elsewhere, the resistance and ture and Ocean Engineering Faculty, the resistance and pro- propulsion data for the trawlers were obtained (Doust 1959) pulsion tests of three traditional Turkish fishing boat models and analyzed statistically. The results were used to develop were carried out, and the results were presented (Nutku an optimization technique using the hull form coefficients 1957). The results also included the comparisons of the per- (Doust 1979). In another study, using the resistance data of formance of the three types. Investigating the resistance and 570 models tested in various ship model testing laboratories propulsion of the Taka and Alametro types, the maximum of Europe, US, and Japan, a regression equation with 13 possible speeds were determined, and hull form and propeller improvements were proposed (Nutku 1962). The resistance and propulsion characteristics concerning the traditional 1 Naval Architecture and Ocean Engineering Faculty, Istanbul Cektirme type fishing boats were determined in a separate Technical University, Istanbul, Turkey. study (Kucuk 1964), where two models of different scales and 2 Maritime Faculty, Istanbul Technical University, Istanbul, Tur- a full scale boat was used and the velocity values in the key. boundary layer of the full scale boat was measured. In an- Manuscript received at SNAME headquarters June 2007. other study, the fishing boats 7 to 12 meters long, known as 194 OCTOBER 2008 0025-3316/00/4504-0194$00.00/0 MARINE TECHNOLOGY “the infantry” type, common in the coastal regions where the were developed, and fundamentally one may regard this Aegean Sea and the Mediterranean Sea meet, were studied. study as the continuation of the previous work performed in Their current hull forms have been traditionally developed the same institution (Kafali et al. 1979, Kafali 1980). These over 90 years. At present, they are built by craftsmen without fishing boats exhibit improved stability and seakeeping char- plans, drawings, or calculations. The first scientific work car- acteristics compared with the traditional boats. Further- ried on these boats is the geosim experiments that took place more, the general accommodation plans provide for a wide in Lake Koycegiz, where for the first time the hull forms were and effective afterdeck. Their hull forms are generated con- obtained. During the geosim experiments, the geosim boats sidering multipurpose fishing characteristics. Free running had been tested followed by the resistance tests, the wake speed for these fishing boats is about 10 knots. Fishing measurement tests, the self-propulsion tests, and flow visu- speeds for these boats are varied between 4 and 5 knots. The alization tests. Analyses of the resistance tests were ex- production the models and tests were carried out in the Ata tended to obtain results for assessing the laboratory’s model Nutku Ship Model Testing Laboratory of ITU Naval Archi- test technique and for the improvement of the hydrodynamic tecture and Ocean Engineering Faculty, with the support of design. The wake measurement tests were made at two dif- Scientific & Technological Research Council of Turkey. ferent waterlines with the help of a Pitot wake rake. The Ata Nutku Ship Model Testing Laboratory has a number of propeller model self-propulsion tests were made in similar experimental facilities for carrying out research and devel- conditions to those of the wake measurement tests. The tufts opment in marine technology that include the large towing method was used in the flow visualization tests. Using tufts tank, the small towing tank, the cavitation tunnel, the cir- of different colors, the flow separation zones were identified culating water channel, the stability tank, and computa- and observed (Kalipci 1995, 1999). In another study, Kukner tional facilities. The large towing tank is equipped with a and Aydin developed a series of fishing boats (Kukner & numerically controlled carriage, resistance, propulsion and Aydin 1997) based on the four boats with prismatic coeffi- open-water propeller dynamometers, and a wave maker. cients of 0.582, 0.606, 0.625, and 0.649, which were optimized Speeds of up to 6 m/s can be achieved. The main dimensions 3.4 ס m, depth 6 ס m, breadth 160 ס in terms of resistance and propulsion by D. J. Doust. In this of the tank are: length case, starting from 27 boats of identical length and 20 boats m. Ship models up to 4.5 m long are used that enable eco- of various properties, a total number of 540 hull forms were nomic and reliable model tests to be conducted for the ma- generated by using a computer program. In the second stage jority of current ship forms. Self-propulsion and wake field of this study, the boats were modeled numerically and the measurements are performed to derive wake quality and pro- hydrostatic and seakeeping calculations (heave and pitch pulsion factors as well as standard resistance tests and open- amplitudes in head seas) were performed. In the third stage, water propeller tests. The cavitation tunnel was designed the influence of the geometrical design parameters on ship and manufactured by Kempf-Remmers of Germany where motions was investigated. Finally, the regression equations partially or totally cavitating model propellers, hydrofoil sec- were developed, modeling direct calculation paths from the tions, and wings can be tested for cavitation both in free geometrical design parameters to the seakeeping character- stream and in a simulated ship wake.