my pontoon boat has a trolling motor that has been rigged to fit on it. when it is down the blades barely go under water,about even with the pontoon. with my son on with me he can set in front seat beside me and it pushes the blades about 2 inches under water and it will move the boat around. if I'm by myself the blades spin out of the water. I want to lower the unit so having to put extra weight in front won't be necessary. I think it will work better lower. my question: is there a depth that is to low? seems like even a few inches makes a big difference. just don't want to go to far. thanks