SPEED VS WEIGHT

 

How much faster is a light ski compared to a heavy ski?

 

This is a hotly debated topic that normally gets all emotional. Here is a more scientific approach.

 

For the technically minded read

http://www.atm.ox.ac.uk/rowing/physics/weight.html#section7

 

For the rest of us the result can be summarised as

the percentage loss of speed is one sixth the percentage increase in mass.”

 

So how does this relate to the Tuesday night races?

 

Let’s take a 80kg paddler and a 15kg boat as the base case. The table below shows how the weight of the boat influences the speed. For a Tuesday night race where the winning time is around 25 minutes, the last column shows how many seconds you will win/loose because of a heavier or lighter boat.

 

Boat weight

Total weight

Change in weight

Change in speed

Time difference over 25 minutes

[kg]

[kg]

 

 

[seconds]

10

90

5.26%

-0.88%

-13.2

11

91

4.21%

-0.70%

-10.5

12

92

3.16%

-0.53%

-7.9

13

93

2.11%

-0.35%

-5.3

14

94

1.05%

-0.18%

-2.6

15

95

0.00%

0.00%

0.0

16

96

-1.05%

0.18%

2.6

17

97

-2.11%

0.35%

5.3

18

98

-3.16%

0.53%

7.9

19

99

-4.21%

0.70%

10.5

20

100

-5.26%

0.88%

13.2

 

Bottom line is if someone is beating you by 27s you’re not going to beat them by getting a boat that weighs 10kg less. But if you beat your arch rival in a sprint finish then the few grand extra you paid for the boat was worth every single dollar.

 

Boasting over a beer….priceless.

 

Converting $$$$ to seconds

 

Fenn has a whole range of constructions, with skis weighing from around 10kg to 17kg. Price of course goes up as weight comes down, with the weight to price ratio working out to roughly $300 per kg. For a 25 minute race that’s only about $100 per second, actually quite a good deal I think.

 

But by far the biggest advantage of a light ski is carrying it down to the water. I does wonders for the self esteem carrying a ski with one hand and waving at the girls with the other. Girls just aren’t interested in a guy who struggles to pick up a ski.…