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A Primer on Sweep Rigging Numbers

BY VOLKER NOLTE
PHOTO BY PETER SPURRIER

We discussed rigging numbers for sculling boats in the previous column and introduced the idea of beginning with what I call “zero-numbers” to get started with a proven measurement and then make further adjustments according to individual conditions. This approach provides a successful way to find the best setups for rowers of different sizes and performance levels in specific situations (crew size, boat availability, etc.). Spring is coming and with it the likelihood that many crews will return to team boats.

Oarlock height has a direct effect on rowing technique since it influences the position of the arms during the drive, the height at which the blades can be carried above the water during recovery, and bladework. 

A lower oarlock height helps with balance but increases arm angle to horizontal during the drive, which generates more vertical force on the handle and consequently more downforce on the blade. This reduces the efficiency of the pulling force, as well as pushes the blade deeper in the water, which creates a number of problems. In addition, a lower oarlock complicates the clean release of the blade at the end of the drive.

Conversely, a properly set higher oarlock helps you find the correct blade depth in the drive, lets the blade extract cleanly, and provides enough room for the handle above the thighs on the recovery to keep the blade off the water. 

An oarlock height of 17 centimeters above the lowest point of the seat works well as a zero-number for most athletes. Lighter athletes or athletes in a boat that is designed for larger rowers should start with 16 cm., while heavyweight men may start with 19 cm. Once this starting oarlock height is set, coaches should observe the outside arms of the crew while rowing. If the outside arm of a sweep rower during the first part of the drive, when the arm is still straight, has an angle of about 10 degrees below horizontal, the oarlock height is properly set. If the angle is different, the oarlock needs to be adjusted.

As in sculling, inboard and spread are closely connected. The formula: Inboard = Spread +30 cm. ± 1 cm. 

The spread influences the stroke length. A smaller spread increases the arc that the oar sweeps across, and this affects the so-called dynamic gearing. This means that a larger arc makes the drive “heavier.” On the other hand, a faster boat reduces the load on the handle, and a larger oar angle specifically at the full-reach position is helpful because it is more efficient. 

Therefore, the zero-number is different for the sweep boat classes: for a pair and coxed four, 86 cm.; for a straight four, 85 cm.; and for an eight, 84 cm. Inboards of 116 cm., 115 cm., and 114 cm. are the starting lengths for the inboard, respectively.

The recommended zero-numbers for the overall length in centimeters of sweep oars for the most-used blade types are given in the following table, adjusted for gender and performance level:

Blade Type                          Skill LevelCOMPSlick, Smoothie Plain Edge, ApexFatBlade
WomenMenWomenMenWomenMen
International373375375377368370
National372374374376366368
Club370372372374364366
Masters368370370372362364

Because the COMP blade is so new, experience and research results are limited. Therefore, its numbers are shaded gray and need to be followed carefully.

After you find the starting numbers for your specific crew based on the above recommendations, go on the water and get used to the rigging. Then try some test runs to see if your rigging needs individual adjustments. Such adjustments may be necessary a few times, depending on the technique, crew coordination, and fitness of the athletes. Here are some general recommendations for what can be done through rigging:

  • The load is too light or the crew “spins their wheels”: Either lengthen the outboard while keeping spread and inboard consistent or shorten inboard and spread by 1 cm. and overall length by 3 cm.
  • The load is too heavy or the crew “labors the stroke”: Shorten the outboard.
  • The stroke is too short (small athletes, inflexible or older athletes): Shorten inboard and spread by 1 cm. and overall length by 3 cm. If not enough, repeat the measure.
  • The crew struggles to get to race stroke rate since the stroke is too long: Lengthen inboard and spread by 1 cm.
  • Novice crew has problems loading up their blades: Lengthen the outboard.
  • Skilled masters crew cannot finish a race strong: Shorten the outboard.
  • The boat has to be shared between the lightweight and open-weight women: Leave spread consistent, but use two different sets of oars with the same inboard, but 2- to 4-cm. shorter outboards for the lightweight crew.
  • Wind conditions change rapidly before a race to a strong headwind, but the crew has only 10 minutes until launch time: Use clamps to lengthen the inboard. Ideally, the crew has used the clamps in training already, so they are used to them.
  • Wind conditions change to tailwind during warmup 15 minutes before race time: In these circumstances, you cannot change measurements on the oar, so the crew needs to change technique by reaching a little longer at the catch, or to move the foot stretchers one setting to the stern. Both measures must have been tried in training so the crew is familiar with them.

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