I guess would come down to how well one can argue how "manually" you are operating the device. That seems to be what the law hinges on, nothing is meantioned in law about motorized devices, which a bait launcher is not. And it is as manual as kite fishing, or trolling a rapala gets, so I would guess that it is legal. Though it is HIGHLY dangerous so be careful, I've seen some horror stories and missing limbs and seen some chunks of meat and bone formerly known as arms and hands etc..