Envisioning a Channel Crossing
Back in 1988 when I first started to study a potential crossing of the 19.5 km Tsugaru Channel in northern Japan between the islands of Honshu and Hokkaido, I had to study the currents between the Sea of Japan on the west and the Pacific Ocean on the east.
Fortunately, the Japanese government had been studying these elements for decades because the Japanese had envisioned a tunnel (called the Seikan Tunnel) that passes under its narrowest point (19.5 km) between Tappi Misaki on the Tsugaru Peninsula in Aomori Prefecture and Shirakami Misaki on the Matsumae Peninsula in Hokkaidō.
Possible Routes
After consideration of the seasonal water temperatures, currents, and notorious eddied, we decided upon three possible routes:
- Kodomari Route starts on Honshu‘s western peninsula at the Kodomari Benten Cape and, hopefully, finishes on Hokkaido as the Tsugaru Current pushes the swimmer in the eastwardly direction with the aim to finish at Shirakami Misaki on Hokkaido.
- Tappi Misaki Route starts on Tappi Misaki on Honshu’s western peninsula with the aim to finish at Shirakami Misaki on Hokkaido.
- Cape Ōma Route starts on Cape Ōma on Aomori Prefecture’s eastern peninsula with the aim to finish on Cape Toi in southeastern Hokkaido.
The Kodomari Route is longer, but is considered to be more conservative with less risk and a higher percentage of success for most swimmers of moderate or slower speed.
The Tappi Misaki Route is shorter, but is considered to be more risky with a lower percentage of success and is generally more acceptable to swimmers of faster speed. Of course, on a day when the Tsugaru Current is not running so quickly and the winds are less than normal, then the decision where to start is based on the captain’s knowledge, experience, and predictions.
Sharks
The potential escort pilots in the 1980’s included squid fishermen and tuna fishermen. The squid fishermen would fish with bright lights that would attract squid to their fishing nets. The tuna fishermen were often frustrated by huge bites taken by sharks of the tuna caught in their nets.
In the process of investigating the possible routes, I went on several fishing trips with different fishermen. It was very hard work and these men knew their surrounding seas extremely well.
Swim Streamers
So when they introduced the concept of a swim streamer as a shark deterrent, I listened carefully. After seeing the marine life in the channel, I was quite motivated to agree with their idea of placing a long cloth alongside the escort boat as a means to ward off the sharks.
Modern-day Swim Streamers in Japan
The following swim streamers are used in Sado Channel and Tsugaru Channel solo and relay crossings:
Unassisted versus Assisted Swims
Under Marathon Swimming Federation rules, use of a swim streamer is considered nonstandard equipment that is categorized as performance-enhancing (see here). So, officially, use of a swim streamer is an assisted swim, but what I have seen in the ocean, I prefer to feel safe swimming while minimizing the possibility of any shark encounters. In general and very specifically, I always follow the recommendations of the fishermen who guided me safely across the Tsugaru Channel in 1989 – and all subsequent crossings.
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