Construction and operation of four autonomous underwater vehicles for lake survey

In March 2000, "Tantan", the autonomous underwater vehicle (AUV) which was designed in particular for lake ecological surveying, was launched. Based on the same concept as Tantan, a dam lake survey AUV "Kuni" was constructed, and launched in February 2001. The third vehicle for dam lakes in the Shikoku region was launched in December 2001. And, the fourth one is under construction and will be launched in March 2002. In this paper, specifications of these four sister AUVs are presented and compared. "Tantan", whose major missions are observation in the vicinity of the thermocline and survey of oxygen concentration near the bed, is currently deployed in Lake Biwa. It is anticipated that they will report special features of the ecology in lakes which cannot be observed by conventional ways.