▁and ▁the ▁har bour ▁floor , ▁while ▁a ▁war ship ▁used ▁active ▁son ar ▁to ▁h unt ▁for ▁the ▁sub marine . ▁ ▁The ▁course ' s ▁nick name ▁of ▁the ▁' Per isher ' ▁comes ▁from ▁the ▁relatively ▁low ▁success ▁rate ▁of ▁ 6 0 %, ▁combined ▁with ▁the ▁fact ▁that ▁students ▁who ▁fail ▁the ▁course ▁are , ▁in ▁most ▁cases , ▁no ▁longer ▁permitted ▁to ▁serve ▁on ▁sub mar ines ▁in ▁any ▁capacity . ▁According ▁to ▁Commander ▁Marc ▁Els ens ohn , ▁Te acher ▁for ▁the ▁ 2 0 0 4 ▁dies el - elect ric ▁course , ▁the ▁main ▁reasons ▁for ▁failing ▁are ▁that ▁the ▁candidate ▁regularly ▁los es ▁situ ational ▁aw aren ess , ▁or ▁shows ▁a ▁narrow ▁focus ▁or ▁over - re liance ▁on ▁one ▁tool ▁or ▁aspect ▁of ▁operations . ▁M aking ▁mistakes ▁does ▁not ▁cause ▁a ▁student ▁to ▁fail ▁automatically , ▁as ▁long ▁as ▁the ▁mistake ▁is ▁recogn ised ▁and ▁corrected ▁before ▁the ▁sub marine ▁is ▁end anger ed . ▁▁ ▁If ▁at ▁any ▁point ▁during ▁the ▁training ▁a ▁candidate ▁is ▁with dra wn ▁from ▁training ▁he ▁will ▁be ▁nominated ▁for ▁boat ▁or ▁hel ic opter ▁transfer ▁and ▁kept ▁occupied ▁until ▁the ▁transfer . ▁His ▁bag ▁is ▁pack ed ▁for ▁him ▁and ▁he ▁is ▁not ified ▁of ▁the ▁failure ▁when ▁the ▁hel ic opter ▁or ▁boat ▁arriv es . ▁On ▁departure ▁he ▁is ▁presented ▁with ▁a ▁bott le ▁of ▁whis ky . ▁A ▁failure ▁on ▁Per isher ▁means ▁that ▁the ▁un success ful ▁candidate ▁is ▁not