I have a 1978 Glastron 15' Sportster, with a 90 HP Mercury OB. When the boat is out of the water, the steering functions fine. When the boat is in the water, and the engine is throttled up, the steering gets very tight. Why is this, and is there anything I can do about it? I hope I posted this in the right place. Thanks!
When the boat is sitting in the driveway there is no engine torque working against the cable. Once in the water the propeller produces torque and causes feedback that you are fighting against. An initial diagnosis would be a worn cable causing drag in the sheath. If the cable is known to be good, look at the bearings in the tube that the engine moves on- see if there is play there allowing a binding condition when the engine is pressing against the bearings. There are many things that can effect the steering effort. Is the torque tab adjusted properly? Is it tight both ways or more so turning left or right?