As a general rule the faster the boat the narrower the span. The inboard is reduced with respect to the outboard. The foot stretcher is moved away from the body so that the catch angle is move further forward. Typically the catch angle would range from 53-55 degrees in sweep and 65-70 degrees in sculling across the boat classes.

Increasing the forward stroke length will increase the load on the rower. A greater force can be exerted on a greater load. This would in turn lead to greater boats speed but only if the rower can accelerate the load. If not it becomes isometric, a static force as seen if you push against a wall. No matter how hard you push, the wall will not move. What we are looking for is a dynamic force, which brings about acceleration in the boat.

Other variables affect the load such as spoon shape and size. By reducing the length of the spoon the oar becomes more efficient because the length of the spoon should not exceed the slip measured at its tip. An increase in width will further reduce slip. It follows therefore that a shorter wider spoon is the optimum shape. This would suggest something approaching a square however whereas straight edges are the norm in aerodynamics, curves are the norm in hydrodynamics. The result would be something between a square and a circle.

But more important than theoretical efficiency is the ability of the rower to handle the load. The range of rowers now extends from lightweight women of 57kilos to heavyweight men weighing 100 kilos plus. This is an enormous difference of size and power, which is not reflected in the range of equipment used in the sport.

A guide of available power is to look at ergo scores. A good time for heavyweight international men is 5'40 and a comparable time for lightweight woman it is 7'00. The power associated with these two scores is 570 watts for the man and 302 watts for the lightweight woman. This means the lightweight woman has 53% of the power available to a heavy weight man.

Power Range

The chart shows average power ranges in Watts from international heavyweight men to lightweight club junior women.

The difference is made worse because boat weights do not recognise this difference in power. The FISA weight limit for boat types is the same for heavyweight men and lightweight women.

When using standard spoon sizes, less powerful rowers should reduce the overall length of their oars and their span. However this too can cause problems. Not only will this reduce the stroke length, which is contrary to the first biomechanical principle, it can have a negative effect on the stability of the boat. As mentioned earlier, a racing boat has negative stability and is only kept upright by the skill of the rower using the oars as stabilisers. The shorter the overall length of the oars, then the less the stabilising effect that they have. Also shorter outboard length reduces the weight in the hand, which makes the oars more difficult to control, especially in windy conditions. It can however still result in a net gain of boat speed by enabling the rower to accelerate through the drive phase.

Another option is to reduce the spoon area. This is not only controversial but also irreversible and therefore should only be considered after testing with more conventional changes to overall length and span.

Another option is to take some of the area out of the bottom back corner "Swan Neck", plus some off of the overall length. This allows for the overall length of the oar to remain the same and the pressure point is effectively move further from the pin maintaining stroke length whilst allowing the athlete to accelerate the system.

Recommended Spoon Sizes Based on Power

Standard spoon sizes are suitable for heavyweight international men, for other groups the spoon length can be reduced according to the following chart. It may seem like a drastic step to cut down the spoon but spoons come from the same mould and only become sculling and sweep once cut to size.

There are two ways to reduce the spoon area, reduce the length or reduce the width. By reducing the length of the spoon the pressure point of the spoon is effectively brought closer to the boat and this reduces the stroke length. This can be overcome by increasing the shaft length so that the overall oar length remains the same and only the spoon length is reduced. Reducing the width is tending towards an oblong and we have already established this is less efficient than one tending towards a square.