LSJ Gloss:βολίζωto heave the lead, take soundingsDodson:βολίζωI cast the line for sounding, I soundI cast the line (for sounding), I sound.
TBESG:βολίζωto soundG:V βολίζω (< βολίς, in sense of sounding-lead), to heave the lead, take soundings: Act.27:28.† (AS)
Thayer:1) to heave the lead, take a sounding 1a) a line and plummet with which mariners sound the depth of the sea