 Like the other specialized archipelago vessels , the hemmema had specific strengths and weaknesses . Although it had superior firepower relative to galleys , its sailing qualities were somewhat mediocre and while highly <unk> under oars , it was still difficult to propel while rowed . A hemmema had the potential to be an effective weapon against galleys , matching their forward firepower and severely <unk> them with its broadside armament . Inside an enemy galley formation , it could <unk> considerable <unk> , but such a maneuver was never achieved in an actual battle , leaving that tactical role <unk> . 
