EFFECTIVE ARC: reducing catch and finish slip

In rowing, efficient propulsion depends significantly on the optimal range of motion of the oar, also known as the oar's arc. The "Total Arc" refers to the full distance the oar travels during the drive, from the catch to the finish position.

To maximize a boat's propulsion, each rower should aim for the same optimal Total Arc. This may vary slightly across boat classes, between sculling and sweep boats, and among different rower skill levels.

However, the efficiency of a rower's drive is ultimately determined by their "Effective Arc." This is the specific distance the oar travels during the drive from the point it is fully submerged and engaged with the water until it ceases to propel the boat forward.

The difference between the Total Arc and the Effective Arc is measured as "oar slippage." This slippage occurs at the beginning and end of the drive when the blade is not fully connected to the water. We refer to these as Catch Slip and Finish Slip.

To achieve a long and efficient drive, rowers should focus on reducing both Catch and Finish Slip to maximize their Effective Arc.

Read more about the stroke length, as well as about the total arc and effective arc.

CATCH SLIP

During the recovery phase, the oar blade travels towards the bow of the boat. Ideally, the blade will start entering the water at the catch position, as the rower reaches their optimal catch angle.

As the blade begins to enter the water, it changes direction and starts moving towards the stern of the boat. This marks the beginning of the "catch slip," which continues until the blade is fully submerged and connected to the water. In proficient rowers, this accounts for approximately 1-3 degrees of the total arc and lasts for about 0.1 seconds. In less efficient rowers, these values are significantly higher.

To minimize catch slip, rowers should focus on the following:

• Catch Preparation: Ensure the blade is squared on time and carried horizontally, close to the water's surface.

• Catch Timing: Begin dropping the blade while it is still moving towards the bow, just before reaching the optimal catch angle.

• Catch Placement: Drop the blade quickly (within 0.1 seconds), burying it at the correct depth and angle. As the blade enters the water, begin extending your legs at the speed of the boat to develop a "boat feel."

• Catch Connection: Once the blade is fully buried, actively suspend your weight on the oar handle, engaging your legs, and begin accelerating the drive. This action will displace water, creating a wave or peak in front of the blade and a valley or hole behind it, indicating that the blade is connected to the water.

COMMON MISTAKES THAT NEGATIVELY IMPACT CATCH SLIP

1. Skying the Blade

   This occurs when the blade moves away from the water during the preparation phase as it approaches the catch position. This often leads to a delayed blade entry, which can then result in "digging" (the blade entering the water too deeply). Skying increases catch slip and shortens the effective arc.

2. Late Placement

   In this scenario, the blade is properly prepared for the catch, but the rower doesn't start dropping it into the water on time. This also causes a delayed blade entry and increases catch slip.

3. Slow Placement

   Here, the blade is prepared correctly and has good entry timing, but it enters the water too slowly. This increases catch slip.

4. Deep or Violent Placement

   This happens when the rower uses too much force, driving the blade too deeply into the water, which results in increased catch slip.

5. Rushed Connection

   This issue arises when the rower actively starts engaging their legs to "push" before the blade is fully buried in the water. Because part of the blade is still outside the water, there's low resistance, causing the blade to move rapidly towards the stern and increasing catch slip.

FINISH SLIP

During the drive phase, the oar blade moves towards the stern of the boat. As it approaches the finish position, the blade will begin to come out of the water. This marks the start of the "finish slip," which continues until the blade is fully extracted. Ideally, this occurs when the rower reaches the finish position and optimal finish angle.

Similar to the catch slip, for proficient rowers a finish slip accounts for less than 5 degrees of the total arc and lasts approximately 0.1 seconds. In less efficient rowers, these values are significantly higher.

To minimize finish slip, rowers should focus on the following:

• Horizontal Drive: Drive the oar horizontally, ensuring the blade remains fully submerged until the point of extraction.

• Pressure Release: As you approach the finish position and optimal finish angle, stop applying pressure on the oar handle. At this point, you cease "driving" or accelerating the boat/oar. This also allows you to be completely relaxed and in full control of your body and the oar, which is critical for minimizing any potential disruption of boat speed at the stroke's finish.

• Disconnection (Separation): After releasing the pressure, for another split second, keep the blade fully submerged and continue moving the oar horizontally at the speed of the boat (boat feel). Doing this allows the blade to separate ("disconnect") from the wave or peak that is in front of it and let the valley that is behind the blade catch up with it.

• Extraction: At this point, the blade should be inside the "valley," meaning the top edge of the blade is already free from the water, and the rest of the blade is ready for extraction. This will be the beginning of the catch slip. Using your outside hand, apply a quick tap-down on the handle to fully extract or "pop" the blade out of the water. Once the bottom edge of the blade is out, begin the recovery phase and start moving the blade towards the bow. During extraction, the blade should not scoop or lift any water; it should come out quickly and cleanly with only a few drops of water coming off the bottom edge.

COMMON MISTAKES THAT NEGATIVELY IMPACT FINISH SLIP

1. Pulling Oar Out (Washing Out)

This occurs when a rower doesn't release pressure before extracting the blade. The handle is pulled downward, and the blade is still driven as it begins to come out of the water. This causes the blade to move very quickly towards the stern while gradually exiting the water, leading to significantly increased finish slip.

2. Early Extraction (Ripping the Blade Out)

In this scenario, the rower releases pressure but doesn't wait long enough for the blade to separate from the peak wave in front of it. This results in increased friction as the blade exits the water, often causing it to lift an excessive amount of water and significantly slow the boat down.

3. Late Extraction (Handle gets Stuck)

Here, the rower releases pressure but waits too long to extract the blade. The blade gets caught by the second, smaller peak wave trailing behind the valley, pushing the blade slightly forward. This shoves the handle back into the rower's body, making the blade extraction rough and difficult to transition into the recovery phase. This slows the boat down and can compromise its balance.

4. Slow Extraction

The rower correctly releases pressure and waits for blade separation but extracts the blade too slowly. Although the blade starts coming out on time, its slow upward movement causes it to get partially caught by the second peak wave. This can result in a slight forward push on the blade, moving the handle into the rower's body and potentially causing it to get partially stuck. The negative effects are similar to, but less extensive than "Late Extraction."

5. Early Feather (Scooping the Water)

This happens when the rower has a correct release, separation, and extraction, but begins feathering the blade too early. The blade will scoop water from the peak wave in front of it, requiring more force on the handle to extract the blade and leading to a rougher extraction. Consequently, the boat loses speed, and its balance may be compromised.

Mastering both the catch and finish in rowing requires a high level of control and precision. Even minor errors in execution can negatively impact boat speed and increase "slip" at these critical points in the stroke. To properly develop these skills, rowers need a clear understanding of the concepts and ample opportunities for practice.