Moored Buoy Systems are one of the most common platforms of Ocean Observations for cost- effective means of obtaining meteorological and oceanographic data. In addition to these, several other modes of unmanned systems have been evolved in the past decades for long term observations such as Autonomous Underwater Vehicles (AUVs), Autonomous Underwater Gliders (AUGs). Thus, as a part of development strategy for new tools to have long term ocean observations with minimum energy consumption, developments are undertaken at OOS, NIOT. This paper presents the preliminary design methodology of one such development being pursued at NIOT i.e. a Laboratory Scale Underwater Glider (LSUG) and a small robotic underwater vehicle which mimics a fish called AquaBot.