What do you have for a yak? I know the Hobie guys hug the rod to there chest with one hand while they pedal. If you are paddling a yak, put it in a rod holder and hope they slam it good. Wouldn't hurt to grab and set the hook.
I'm no tube and worm expert but from what I'm noticing.....short hits seem to be the norm....you could try a trailer hook.
http://www.kayakfishingstuff.com/dru.../tube-and-worm
http://www.canoekayak.com/fishing/tube/
http://www.ultimatekayakfishing.com/...-and-worm.html