The influence of dihedral bulbous bows on the resistance of small fishing vessels: A numerical study

Environmental aspects in the shipping industry are nowadays taking more relevance. Independently of the type of fuel used, good drawing lines in ships might help with the emission mitigation and also with the ship efficiency. In the fishing industry, ships lines in non-developed countries and in small traditional ships are normally not optimized what leads to a no optimal use of the resources and operation. In this work this topic is treated. The lines of two fishing vessels are studied numerically and compared with towing tank experiments. Those lines from a displacement and a semi-displacement hull, are optimized by adding a new type of bow named as dihedral bulbous bow. This bow produces a reduction over 10% of the ship's resistance. This work focuses on explaining numerically why that difference occurs. The bulbous bow reduces the pressure resistance by softening the flow that reaches the bow.