母港 is read as ぼこう (bokou) and means home port.
ぼこう
bokou
ぼせい
motherhood
ぼせいあい
maternal love
ぼせん
depot ship
ぼしたいこうせい
ability to oppose the thumb
ぼぶんか
(one's) native culture
ぼせいほんのう
maternal instinct
ぼしとも
both mother and child
ぼかんすう
generating function
くうこう
airport
みなと
harbour
かいこう
opening a port to foreign vessels or trade
にゅうこう
entry into port