You should use full throttle to take off regardless. Surface drives need to produce alot of thrust to get the boat on plane. Ive never heard of anyone having success with that small of battries. Better bats will help but not if you are trying to plane at part throttle. If you use a big diameter 2 blade like a 642 octura or a CF45 plastic prop you will come out of the hole much better but they are harder on your batts.