1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 56Get this manual
OUTBOARD INSTALLATION
Tilt Pin Adjustment
Placing Tilt Pin in Lower Holes
1Lower the bow2Result in quicker planing off, especially with heavy load or stern heavy boat3Generally improve the ride in choppy water4Increase steering torque or pull to the right (with the normal right hand rotation propeller)5In excess, lower the bow of some boats to point at which they begin to plow with their bow in the water while on planeThis can result in an unexpected turn in either direction called bow steering or over-steering if any turn is attempted or if significant wave is encountered