ε3857Ἐφ' ἕνδεκα κώπαις
on eleven oars
There is a naval order so called. "Raise a great wave [sc. of applause] for them [and send out a good Lenaean hubbub on eleven oars]." It is a metaphor from those rowing on eleven oars.
Ἐφ' ἕνδεκα κώπαις· κέλευσμά ἐστι ναυτικὸν οὕτω λεγόμενον. αἴρεσθ' αὐτῶν πολὺ τὸ ῥόθιον. ἀπὸ τῶν ἐρεσσόντων μετήνεγκεν ἐφ' ἕνδεκα κώπαις.