This paper proposes a low-voltage DC (LVDC) architecture to replace the conventional low-voltage AC (LVAC) architecture in a diving support vessel (DSV). A genetic algorithm based optimization algorithm is also adopted to minimize the fuel consumption of the DSV. The DSV in study spends a majority of its time in dive or dynamic positioning (DP) mode, in which all four diesel generators are online to ensure redundancy and fast response to unpredictable sea conditions. Conventionally, the allocation of power generation for the diesel generators is performed via equal loading, which may not result in minimal fuel consumption. A comparison of fuel consumption in normal operation modes for the conventional LVAC and proposed LVDC architectures are performed, both with equal loading and optimization with GA. Additional constraints are then applied for fuel consumption comparisons in dive and DP operating modes.