Its commonly refered to as where the anti-ventilation plate (flat area right above the prop) is in relation to the true bottom of the hull when the plate is parallel to the hull. The distance is measured in inches and in a verticle line.<br /><br />Boat racers sometimes refer to the propshaft centerline instead of the AV plate.<br /><br />When you talk about increasing the X dimension that means you raise the motor so its mounted higher on the transom or bracket. Sometimes its confusing because people refer to the trim as raising or lowering instead of in and out. Trim angle is measured in degrees (positive and negative) and in the arc that follows the lower unit as it goes thru the trim travel.
