For decades glass fiber reinforced composites have been extensively used for construction of small and medium sized vessels. With the rise of environmental awareness, in all industries including shipbuilding, new, more sustainable composites are being sought to replace the glass fiber reinforced composites. These new materials should have equal or better mechanical properties, price, availability, and resilience. They should also be recyclable and safe to use and work with. One of the more prominent candidates to replace the use of glass fibers are natural linen fibers. To build experience in the use of linen fiber composites, the EU has funded a project to build environmentally sustainable catamaran ProEco by company Marservis d.o.o. The catamaran superstructure is made from bio composites with biodegradable epoxy resin reinforced with linen fibers. The goal of this thesis is to determine layers of bio composites needed for the laminates to be used in production of catamaran hull using the Finite element method (FEM) and to build upon the previous work from other students in an attempt to prove the viability of linen reinforced bio composites in ship design. The catamaran design must comply with the strict criteria of Croatian register of shipping. Data obtained from the composite manufacturer is validated with experimental data obtained from the other research papers written by faculty colleagues. Furthermore, this data is then used in calculations conducted to determine the bio composite laminate properties of individual hull segments. Then, with known laminate properties global analysis of the hull is conducted using FEM. The loads used in the analysis are taken from the Croatian register of shipping. Hull components that were deemed critical were submodeld and analyzed.