On 14 September, I did my longest swimming event this year in London, the Dock2Dock 15 km event. Last year I did the 10 km event but it happened just 2 days after I swam the English Channel so I was extremely tired and the result did not have a reference value of my actual ability, although it qualified me for the 15 km this year.

My swimming ability was far behind most people I knew, and I believed that 10 km would be best suited for my ability, while still called a “marathon swim”. However, my partner Ingrid registered for the 15 km so I wanted to do the same course as her, in order to get a comparison to decide if we can swim channels in tandem in the future (especially the Gibraltar strait), so I also registered the 15 km despite it would be too much for my ability.

There were 3 known Hongkongers doing the event, me (15 km skin), Ingrid Chow (15 km swim) and Ka Ho Tam (Mato Hak) (15 km wetsuit).

Unlike last year when the event was held in a heatwave, with a credible threat that the wetsuit category might be removed (although it didn’t happen), the weather this year was on the colder side, with the official water temperature at 16.7°C, a bit lower than I expected as well.

The course was 3 anti-clockwise east-west sausage loops of 5 km between and (2.5 km apart), starting and ending at the northern shore of the bridge. Although I really hope that I could get my time under 5 hours (so that I could average 3 km/h and meet the speed requirement to swim the Gibraltar strait), my time from the 7.5 km national championships meant that it was impossible for me to do so, therefore my aim was to complete 15 km between 5:15 to 5:30, hoping to complete each loop in 1:45 – 1:50.

The 15 km race was mass start only, and the mass start wave of the 10 km race started 15 minutes afterwards. As there was no lap timing, I used my watch to record split times as advised in the swimmers’ manual. I started at much less effort than I did in a 7.5 km race, and reached the first turning point, 1.5 km away in 30 minutes from the race start, and returned in 31 minutes. It took me another 22 minutes to the second turning point and another 22 minutes back to complete the first lap, totalling 1 hour and 45 minutes.

However, I couldn’t keep the speed in the second lap. The 4 sections took me about 34, 36, 24 and 28 minutes, i.e. 2 hours and 2 minutes to complete the second lap. I fed twice on both the turning points.

In the final lap, my speed dropped further and the sections took me 44, 36, 23 and 32 minutes, 135 minutes in total. I fed once under the bridge at the opposite side to the start / finish. I could no longer pull to the end and complete my stroke during the final lap.

My final result was 6:01:40. I was totally disappointed about my time that I couldn’t even keep 2.5 km/h all the way, and I need 3 km/h to swim the channels I want in the future. The speed drop was extremely concerning as well that each lap was 15 minutes slower than the one before. I was the 8th among the 14 swimmers who completed 15 km in skin, with the fastest time being 4:30:36, 1.5 hours faster than me.

I looked for Ingrid but couldn’t find her. It turned out that she didn’t complete the whole 15 km and got out after 2 laps. Mato also got out after 10 km only.

Although I did complete the whole 15 km, it was too much for me at my current ability. 10 km would be more suitable for me and my time would be much better. I wouldn’t be able to swim the channels I want based on the performance shown above, as my speed dropped lap by lap.

I still plan to do this event in the future, but probably 10 km only until I could reasonably keep the whole race effort for the whole 10 km, achieving a speed similar to my 7.5 km race.