Motor Alignment off?

Ok, so I just picked up a 1999 Nitro Fish and Ski boat with 150hp mercury nitro serious 2 stroke outboard motor. I test ran it yesterday and noticed that the boat tends to want to go to the right so I have to put a firm grip on the steering wheel and put a bit of force on it to keep it from going to the right. What's causing the motor to pull to the right like that? I checked the stabilizer thing (grey object looking like a shark fin, just right above the prop) and it's not broken or anything. Does anyone else experience this on their motor? Is this an easy fix? I am pretty handy with the tools and have done work on my previous 150hp xr6 motor myself. Please help because I have no clue where to begin checking on this problem.

Try adjusting that shark fin thingy / sacrificial anode.---------Some experimenting may be required.----Don't paint that anode either.

Looking down at it think of it as a clock w/6 o'clock at the back fin end. Move it clockwise 2 hour increments from the current position.

I took another look at it today and noticed that the fin was a bit off to the left. I will readjust it to the center tomorrow then do a test run some time during the weekend. Thanks guys.

Running at low speed with motor trimmed under will cause this condition, the torque tab is only good for slow speeds as when its on plane it has no effect...