This paper reports on the development of a high performance, ruggedized multimode star coupler intended for use in fiber optic data transmission networks aboard naval surface ships. The coupler was designed to exhibit superior optical performance, both in terms of low loss and highly uniform coupling. It was also designed to survive a range of severe environmental and mechanical tests, including impact from a 400 lb hammer dropped from a 5 foot height, and a temperature range of -62 to 125°C. The coupler sizes produced ranged from 8 x 8 to 64 x 64 port devices. Essential features of the design along with sample performance data are presented.