I have a 1981 Glastron with a 90 hp Mercury. Just bought it and decided to go out tubing. Works fine til I give her gas and then it pulls the tube under water. That's only about 1/2 throttle. Now,,,,I'm using a 60 ft. rope and connecting on the transom of the boat right where I strap it to the trailer. It just seems too low as when I'm moving it's under water. These are the only eye hooks I have on the rear. Any ideas?