2002 Mercury 25hp 2 stroke Tiller

[Stump Bumper]

Ok guys, I'm looking for some advice from the marine mechanically inclined. On my 15' mv Alumacraft aw, is the 25hp Merc. Ever since I got the boat from my father-in-law, the motor has always pulled hard to the left (pushing the front of the boat to the right). No matter what speed the boat is running, I have to fight with the motor to keep her straight. As soon as she's taken out of neutral the motor turns to the left. The trim tab under the cavitation plate has always been turned as far to the right as possible. There is a "friction bolt" that has "decrease" and "increase" written on it but I'm not sure what that does. It looks like it would straighten the motor vertically but again, I'm not sure. There is no damage to any part of the motor or the fin that sticks down below the propeller. The propeller has a few spots on the blades that looke like it may have hit something that flattened out the edge slightly but no more than 1/16". Take a look and the pictures and let me know what you would suggest. When the motor is all the way down, the cavitation plate does line up with the bottom of the boat. Thanks for your help.

 

[restornator]

Turn that sacrificial anode to the right until you are happy with the performance.

 

[JMichael]

The lever with the "increase / decrease" is the steering tension. In other words, turn it one way should add friction/resistance to trying to steer/turn the motor. Turning it the other way should make it easier to turn the tiller handle from left to right. Looking at your trim tab it appears you have it set to max left turn so it sounds like it's doing what you have it set for. Try turning the trim tab to the other side and see if that doesn't help.

 

[onthewater102]

Not sure if you've got a weight distribution issue in the boat or not, could be heavy to the starboard side too, but the trim tab looks to be way out of whack. Simple adjustment.

 

[muddywaders]

This problem(torque steer) seems worse with the merc 20/25 than other 25hp motors.Not sure why may have to do with the design of the stock prop.It can be really bad on lighter hulls.One thing that helps is to grind material off the zinc(the part inside the leg) to allow the fin to turn a few more degrees-this will only help at higher rpms.It would be nice to be able to let go of the tiller at slower speeds without the boat turning.

 

[Callmecaptain]

Always turn the trailing edge in the direction of the pull. Make small changes at a time, you'll find the sweet spot. Took me about 4 or 5 times to get mine right.

I'll probably have to readjust my trim tab when I put my new prop..

 

[JMichael]

It would be nice to be able to let go of the tiller at slower speeds without the boat turning.

If you tighten the steering tensioner (that's the other thing he's asking about) you'll be able to let go at slower speeds without the motor flopping around. Of course that requires the system to be functioning and adjusted correctly, so worn parts or improper adjustment could prevent this from working as designed.

 

[crazymanme2]

If moving the tensoner to increase doesn't work there is a nyloc nut at pivot point that needs to be slightly tightened