They vary in size from about 5,000 to 15,000 tons gross, with speeds from 12 to 19 knots.
Ziyohlukana ngezilinganisi ukusuka kwiitanki eziyi5, 000 ukuya kwi15, 000 yeetoni ngomlinganiso nesantya sokusuka kwi12 ukuya kwi19 yamaqhina.