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Calculated SWOLF score on Forerunner 945 is off by a factor of 2

Hi,

I noticed an inconsistency with the SWOLF score calculated on my Forerunner 945. Here is the situation:

I am swimming in a 50 m pool. The watch is set to 50 m pool size and correctly recognizes laps (21) and total distance (1050 m). From the data I have collected, I can manually calculate the SWOLF as it is described on the Garmin support site [Link]:

28 strokes per 50 m lane > divided by 2 = 14 strokes per 25 m lane
2:21 min / 100 m > divided by 4 = 35.25 seconds per 25 m lane

Adding these values up results in a SWOLF score of 49.25 (normalized to a 25 m pool length).

However, my Forerunner 945 calculates a SWOLF of 99 on the basis of the values above. Curiously, this is rounded up exactly double the actual SWOLF score when manually calculated.

So my conclusion is, that I am either missing the point completely or the SWOLF calculation is off by a factor of 2?

Best regards

Kris

0 MarinusvD over 2 years ago

As far as i see it is correctly calculated. 99 on basis of 50 meter lane.

I do a swim in 25 lane and my swolf is 44 tot 45.

my swim speed is 2.05 min/100 m and about 13 strokes per lane

This makes 31 + 13 = 44 Swolf

So swolf is calculated on the base of the lane length noting more. But if you want it for yourself to the 25 meter you can take your calulated swolf divided by 2. so in your case it is 99 : 2 = 49

0 8148212 over 2 years ago in reply to MarinusvD

Yeah you are correct, the SWOLF seems to be calculated with a 50 m pool length. So I have a SWOLF for a 50 m pool here.

However, It seems counter intuitive to me. The SWOLF score is supposed to give me insights about my swimming performance regardless of the pool I swim in. Therefore it should be normalized to one standard pool length and not calculated based on the currently used pool length. As I understood the Garmin Info page about SWOLF the base length is 25 m. Open water swims for example are divided into 25 m segments via the gps track to calculate the SWOLF score.

The current analysis means that when I switch back to indoor pools (25 m) in the winter I will have a 25m-pool-SWOLF. Whereas currently I am recording 50m-pool-SWOLFs at the outside facility. Of course this is not a deal breaker, because I can just divide the SWOLF by 2, as you mentioned already. However, I would need to check first whether the activity was done in a 25 or 50 m pool.

In my opinion the SWOLF should be normalized to ONE standard pool length so that it is easy to compare between training sessions.

0 MarinusvD over 2 years ago in reply to 8148212

partialy agree to standardize tot 25 meter pool. around 44 of lower Swolf is efficient by the way

0 Dr Phil over 2 years ago in reply to 8148212

8148212 said:
I would need to check first whether the activity was done in a 25 or 50 m pool.

I'm guessing it would be pretty clear. If you know your SWOLF to be around 100 for 50m there will be a significant difference when you go to a 25m pool. It would be half of that and very obvious.