If you are small club, or are (re)building a club, it can sometimes be difficult to predict the performance of your crew due to fluctuating crew numbers at training sessions.
As a coach we can measure all we want but if the crew numbers are fluctuating every session, it would be hard to know if they are improving as a whole or not. Are your race starts improving? Will that technique tweak result in actual faster times?
Wouldn’t it be great to be able to get an idea of how your 8 paddler crew would go if it was scaled up to a virtual 10s crew? And then, at a later session, compare your 12 paddler crew to the same virtual 10s crew?
I think we can get an idea of how our crew would perform if we could add virtual, cloned paddlers made up of the average weight and average power of our current crew.
How Do We Do This?
I have broken the strategy to work this out down into two effects that adding paddlers have on boat speed:
- Adding crew members adds dead weight into the boat -> slows the boat down.
- Adding crew members adds power to the boat -> speeds the boat up.
Given that logic, we should be able to predict the speed of a virtual boat by working out the effect of adding the weight and power of the people that need to be added (or removed).
e.g. To work out the speed of a virtual 10s boat from an existing 8-person crew we need to:
- Add the weight of 2 additional paddlers and calculate how much that would slow the boat down.
- Add the power of 2 additional paddlers and calculate how much that would speed the boat up.
- Using those two factors, apply them to the current crew speed to see what the virtual boat would do.
How Much Does Adding Weight Slow the Boat Down?
How much does adding weight to a boat slow it down? Unfortunately, This is not an easy calculation as adding weight not only adds weight, but also lowers the boat deeper into the water which creates more drag.
If you want to read a simple way to calculate the effect of adding weight has on boat speed, have a look at this article.1
Based on the article, the change in dragon boat speed is equal to -1/6th of the additional dead weight. From that we can work out a multiplier that we will call the Velocity Factor from weight changes.
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