On a forum, I left a short response to Iron Mike‘s comment about his DNF rate, saying from my heart that

44% DNF rate?! I would have already given up the sport.

I then discovered he has written a blog article responding to this sentence, and happened to read it!

Although my open water swimming experience is very little and I haven’t got a single DNF yet in my 7 open water swimming competitions (I got a DNF in an aquathon in the past because I didn’t exit the transition at the correct place), I’m a very experienced orienteer and the number of DNFs are too many for me to list out individually. I think, the major reasons for DNFs in orienteering, apart from injury, include:

1. speed (you can’t run fast enough for the course time limit), specific to the kind of terrain the race takes place.
2. technical difficulty (the ability to interpret the map, plan the course to the checkpoint and execute it perfectly)
3. carelessness (have you checked the control code? have you missed a control?)

Different from swimming, orienteering is a sport of unknown – you never know how difficult the course is until you run it. This alone already makes orienteering really fucking interesting. The only guidance is the expected winning time, which is calculated for elites. Therefore, DNFs are totally unavoidable from the beginning. When I started orienteering, I signed up every race on the calendar, but some of them were too long or too difficult for me that I got DNFs. After that I simply skipped those races if they were known to be difficult, e.g. the annual orienteering championship which was explicitly said to be designed for elites, and did easier races instead until I got some improvement in my score, then I started to sign up some of the more difficult races.

Orienteering is a very low-cost sport – the entry fee is commonly only less than HKD 150, some even as low as HKD 60, and the best form of training is to race! Therefore DNFs are not a great deal and people race every week.

However, long-distance swimming, or other similar endurance sports, are a completely different beast. The course is well-defined even before you sign up, the water temperature can be estimated within 2 degrees most of the times, tides can be predicted, only the weather is unknown before the race. As Iron Mike says, the major reasons of DNFing a marathon swim are speed and preparation, however, these two are exact factors that can be taken into consideration when signing up.

• speed: This is fairly easy to predict if you will meet the cut-off or not, if there is no current (which is the case of most lake swims). Just put your recent speed into the Riegel formula, or if you have more data, get a regression formula to predict the completion time. However it is a problem if there is current, which make me afraid if I will DNF a race because the current is adverse and I don’t have enough speed to overcome it before the cut-off.
• preparation: I can’t imagine DNFing a race due to preparation. Mike I dare not criticise you but I really have questions about your DNFs. #1 you claimed that you were not physically prepared to swim a 10 km, #2 you claimed that it was too cold, #3 you also claimed that it was too cold, and #4 you claimed that you used a wrong race strategy, all these reasons could be avoided by proper training. I’m not qualified to say what is proper training, but for all my races, I train for 3 aspects:
  • distance: I follow some guidelines to make sure that I am prepared for the distance, including weekly amount at least the race distance, 2/3 of the race length in the longest training swim, and the race length over a weekend
  • temperature: I swim in similar temperature of the race. If this is not possible I won’t sign up the race at all (which means I am not doing anything under 15°C as the lowest sea temperature in Hong Kong is around 15 – 17°C)
  • water condition: If the race is rough water race, I swim in rough water in my training

  I’ve already got my first marathon swimming done using the above method, and will continue to do so for my second marathon swimming, probably coming early next year.

As endurance sport training is really hard and requires a lot of effort and dedication, I am really scared of DNFing a race. Unlike doing orienteering where you race every week, the training cycle of an endurance race commonly takes months, or even up to a year! which a DNF means a year wasted. Unlike doing orienteering, I don’t take races as learning in marathon swimming, rather as an exam with pass or fail which retaking is costly.

Although I have many marathon swimming goals ahead, like 14 km, 21 km, and so on, I’m doing them progressively, one serving as training of the next one, and I really want to do them without failure such that I can execute my training plan on time. I don’t want to see my failure in marathon swimming yet. Mike, I also hope that you can prepare your marathon swimming well such that you no longer get any DNFs in the future.