Proper shaft length selection is more critical with bow mount motors (as compared to transom mount). Bow-to-water distances tend to vary more from boat to boat, and the bow moves much more on the water than the transom. As such, it's important to make sure you select the proper shaft length. Start by measuring the distance from the horizontal mounting point on the bow to the waterline, then add 20" to this measurement. Generally, you will want a shaft length that is equal to or greater than this sum, but not less. The following factors may be further considerations: