Rigging Terms and Measurements

Clip-on Load Adjusting Mechanism. The CLAM slides on and off the shaft and fits over the sleeve to quickly adjust the inboard of an oar or scull. Adding one CLAM increases the inboard by 1 cm, thereby decreasing the load you feel on the oar(s).
Oarlock Height
Vertical distance from the lowest point on the front edge of the seat at the front stop position to the midpoint of the oarlock shelf. This determines the level of your hands during the pull phase of the stroke, when the blade is just buried. If your hand level is too low, you will not have room to maneuver and feather your oar. If it is too high, you will feel uncomfortable as you pull through the water, and your oars may tend to wash out (come out of the water prematurely) during the stroke.
The distance from the end of the handle to the blade-side face of the collar or CLAM The greater the inboard, the lighter the oar will feel in your hands, and the lighter your load will be when pulling through the water.
Also called gearing. Just as the gearing on a bicycle determines the force felt at the pedal, the load defined by certain rigging measurements determines the force felt at the oar handle. For example, you can increase the load by doing any of the following: decrease the inboard; increase the outboard; increase your reach; use a longer oar without changing inboard or spread.
The distance between the tip of the blade and the blade-side face of the collar or CLAM. The greater the outboard, the heavier the oar will feel and the greater the load will be.
The amount by which the hands cross each other at the midpoint of the sculling stroke. The overlap is a function of the inboard and the spread and is generally described as half of the difference between the spread and twice the inboard. Increasing the inboard will increase the overlap, unless you increase the spread accordingly at the same time. Overlap is a matter of personal preference, but is generally recommended to keep it between 12 and 20 cm. In general, taller people row with more overlap and shorter people row with less.
The vertical axle extending up from the end of the rigger around which the oarlock rotates. The expression “through the pin” refers to the relative position of the pins and your seat at the beginning of the stroke. If the seat passes to the stern of the pins, you are said to be rowing “through the pin.”
The angle of the blade away from perpendicular during the pull phase of the stroke. This is the net result of the pitch in the oar itself and the pitch in the oarlock and the pitch in the pin. Too much pitch makes it hard to bury the blade; too little pitch makes it too easy to pull too deep through the water.
The distance between the two pins on a sculling boat, or the distance between the pin and the center line of a sweep boat. Spread interacts with the inboard setting to determine the overlap of your hands when the oars are perpendicular to the boat. Also, the greater the spread, the smaller the arc that your oar blades sweep through the water.