Ocean current energy is a promising ocean renewable resource. In this technology, turbines play a critical role in converting kinetic energy into electricity. While studies have extensively analyzed blade geometry and material selection, the influence of support arm spacing on the structural performance of vertical axis ocean current turbine blades remains under exploration. This study examines the relationship between support arm distance and the ultimate strength of turbine blades using Finite Element Method (FEM) simulations in ABAQUS CAE. Composite blade models were analyzed under varying strut distances to evaluate deformation, displacement, material failure, and safety factors. The results show that optimal support arm spacing significantly enhances blade performance, with the ideal range identified as 0.572 L to 0.71 L (where L is blade length). At the optimal position of 0.71 L, deflection was minimized to 2.1% of the blade length, ensuring improved load distribution and structural stability. These findings highlight the importance of support arm positioning in optimizing turbine design.