Dr. Neethiselvan, NAMALA SHAJEEVA, J2017-06-022017-06-022016http://krishikosh.egranth.ac.in/handle/1/5810013939A study was carried out to analyze the impact of increased engine power on the performance of different size class trawlers of Thoothukudi .The study revealed three different size class trawlers with the OAL of 40- 50’, 50- 60’ and above 60’.About 50 % of the trawlers were found to be with the OAL exceeding 60 feet powered with the engines ranging from 400 to 600 hp. Seven trawl designs were reported and were analyzed for nine parameters namely (i) relation between engine power and head rope length, ii)drag resistance based on twine surface area,(iii)optimum towing power based on speed length ratio and displacement, (iv)optimum operational speed, (v) fuel consumption during free running, (vi) fuel consumption during trawling, (vii)total and excess carbon emission,(vii) net profit and (ix)Benefit cost ratio of trawling. Five parameters namely (i) total length,(ii) length at water line,(iii) breadth at water line ,(iv) depth and (v) draft were measured for three different size class trawlers. Trawls operated from vessels with the OAL ranging from 60 to 65 feet were found to have 2 times excess breadth of webbing along overhang. The increased breadth was found to be responsible for the increased drag in all the seven designs studied. The study stressed the need for reducing the drag resistance through the introduction of effective designs without complicated take up ratios at belly .The engine power was found to be high tohave higher free running speed which was found to be mainly responsible for the increased fuel consumption particularly for higher size class vessels. It was found that vessels with the OAL exceeding 60 feet are mere suited for multiday fishing thus paving way for reducing fuel consumption per trip through reduced voyage time and operating the vessel at optimum free running speed of 8.4 knots instead of 11.5knots. Fuel consumption during towing alone account for 40.5 to 48.3 % of the total fuel consumption. Reducing the drag resistance through the introduction of fuel efficient trawl design besides optimizing the trawling could result in a daily saving of about 130 and 140 liters of fuel by trawlers with the OAL of 50 – 60’ and above 60’ respectively. The analysis on the CO2 emission indicated that about 5,78,600 kg of CO2is released daily due to the operation of trawlers in Thoothukudi during peak fishing season, out of which about 75.2 % was contributed by the trawlers with the OAL exceeding 60 feet.This can be reduced by about 40 % through efficient trawl design and allowing higher class vessels with the OAL exceeding 60’ for multiday fishing. The BCR indicated reduced profitability of trawling which may be attributed to economic over fishing.ennullThesis