When a vessel proceeds toward an overhead power line (or cable) ， itS radar receives thc raclar refiected waves f ｝ om the overhead power line and the echo appears on the radarscope as a single echo f｝ om a small boat always at right Imgles to the line ofthe cabie ． GeneiUlly it is known well that this echo appears on the radarscope ． However the su 伍 cient comparative evaluation is not earried out about the characteristics ofthe radar re 且ected signal from the overhead power line and the sma11 boat． In this paper we exarnine the characteristics ofradar signal intensity and angular size ofboth echoes by the comparison of the theoretical analysis and the actUal observation resu 】 ts which was executed at Kurushima Kaikyou． The results clearly identifies as follows ： 1． The echoes ofsmall boats are more 置 ikely to appear on the radarscope ， at a distance of300m or less from the overhead power line ， than the echoes ofthe power 1ine ． 2． The echoes ofthe overhead power line are more like 且 y to appear on the radarscope ， at a distance of900m or rnore from the oyerhead power line ， than the echoes of smal 且boats ． 3． The angular size ofechoes suitS closely the antenna reception pattern which is given as a fUnction of aZimuth angle and threshold level ．

Abstrac重The authors previously tried to fbrmularize the signal h〕tensity ofthe radar echoes from the overhead power