AIS has not spread through almost all small vessels now . Since a small vessel hides in the shadow of a breakwater or a wave easily and it is hard to catch it by a radar , the spread ofAIS is desired . In this paper, the analysis and the questionnaire of data perf () rm consideration about the practicality ofClass B AIS and spread which are AIS fbr vessels without duty . Our investigation showed that the degree and notability ofthe spread ofAIS ill a small vessel were vely low、 111 asmall vessel , they are common knowledge and low − pricing about AIS spread . It isimportant to advertize the validity ofAIS in each organization conoerned , Moreover, it is necessary to advance popularisation by holding down a price .