Overnight across the Kuroshio Current

Overnight across the Kuroshio Current

Originally we planned day-hops north from Okinawa all the way to Kyushu, the southern-most of the three largest Japanese islands. But as we sat in Amami looking at the weather forecast and our schedule, it became clear that we should probably skip a few of those stops and head right for Kyushu. Several things contributed to this decision.

A few of the stops we’re skipping are tiny islands. They have populations in the low triple digits. We’d heard they might not be all that welcoming of foreign visitors in the wake of Covid, and even if they were, the residents speak little English and don’t have much infrastructure, restaurants, or activities for visitors.

Weather has been a little bigger challenge than I initially expected. It’s still spring here. Thirty-five-knot winds are not uncommon. Every three or four days a system rolls through with gusty weather. From astern this wind is tolerable, but anywhere forward of the beam makes for a pretty uncomfortable ride. When the wind is behind us, we want to make some miles, and it was supposed to be behind us for a few days before clocking around and blowing from the north again.

Finally, our own schedule. We’re picking up Don and Sharry’s son, daughter-in-law, and granddaughter in early April in Fukuoka, and we don’t want to be late.

Decision made, to Kyushu we go!

We left Amami at dawn, about 6:15 a.m. and set a course due north.

One of the many small, rugged islands along our route

We weren’t certain of our destination, but programmed Hirado, a small community with a float (rather than a wall) that Starr had visited once before and enjoyed. Hirado is about 300nm north of Amami, but the short distance belies the challenges of the route.

The biggest challenge is the Kuroshio Current, a swift-moving oceanic river that rivals the Gulf Stream in strength and influence. Here’s how ChatGPT summarized the Kuroshio Current:

The Kuroshio Current is a warm, powerful ocean current that flows northward along the east coast of Taiwan, across the East China Sea, and into the western North Pacific Ocean. It is a western boundary current similar to the Gulf Stream in the Atlantic Ocean, and it plays a crucial role in the climate and ecosystems of the Pacific region. The Kuroshio Current carries warm water and nutrients, influencing the distribution of fish and other marine organisms, as well as weather patterns. The current is associated with the formation of eddies and meanders that can impact ocean circulation and climate variability. However, the Kuroshio Current also carries trash and debris, which poses a significant threat to marine life and ecosystems.

For years, I’ve walked by a Japanese fishing boat in Prince Rupert, BC named Kazu Maru. This boat and the park that it lies in are a monument mariners who’ve been lost at sea, but I never understood how the boat drifted across the Pacific. Turns out it was carried across by the Kuroshio Current.

The Kazu Maru, a Japanese fishing boat that washed ashore in British Columbia thanks to the Kuroshio Current

This article published in the Smithsonian Magazine is a fascinating look at the anthropological impacts of the Kuroshio Current. The short version: Japanese sailors have been swept across the Pacific forever, washing ashore in the Americas and Hawaii and influencing local culture thereafter.

Crossing the Kuroshio Current was interesting. For one thing, there was a lot of trash. Nothing huge, but we saw lots of plastic and occasional 55-gallon drums. I worried about what we couldn’t see: nets and lines, and also shipping containers or larger debris that could do real damage to the boat.

As we entered the current, water temperature rose dramatically and then dropped just as quickly as we left—during one three hour period I saw a seven degree temperature swing.

We crabbed sideways and our heading often differed from our course-over-ground by more than 25 degrees as the current swept us sideways. Seas grew lumpy and confused.

To add to the fun, there was a lot of traffic, all much larger than Starr. Many of the ships were 1000+ footers cruising at 20+ knots. The crews were professional and accommodating and only once did we need to change course.

By dawn we were out of the current, but Starr didn’t feel quite right. We didn’t notice any vibration, but she was sluggish. Our speed was down a couple of knots and fuel burn up. We didn’t see anything trailing behind us, nor did we hear anything bumping against the hull like there likely would be if we were dragging something from the fins or bulbous bow. I speculated that we had something caught in the rudder, but investigation could wait until we stopped for the day.

Passing Hashima Island, an abandoned island that once supported subsea coal mining

Given our slower-than-expected speed, we wouldn’t make it to Hirado by nightfall. Instead, we pulled into Iojima Island, a few miles west of Nagasaki. After tying up to a float, I put on a snorkel and mask and jumped in. Sure enough, lots of line wrapped around the starboard rudder.

We gathered up the hookah gear, our trusty bread knife, and I donned a wetsuit. The water here is about 62 degrees Fahrenheit–much colder than last time we were tangled–but thankfully much calmer, too! After a few minutes of cutting, we pulled this mess aboard:

The next day we explored Iojima on foot. The island is quiet, with an extensive resort. It’s notably colder here than it was further south and it felt very much like the off season.

Two harbors in Iojima. Starr is at the northern (upper) harbor along a concrete float.

It’s easy to see parts of Nagasaki from Iojima, including the impressively-large cranes at the Mitsubishi Heavy Industries shipyard. They can build some of the biggest ships in the world there.

We planned to spend a second night at Iojima, but our visit was cut short when a local construction barge told us they needed our space! We decided to motor the short distance into Nagasaki to Dejima Wharf, where Starr had stayed back in 2010. More on that in the next post.

  • Peter Le lievre
    Posted at 14:04h, 30 March Reply

    7 degrees temp swing. Wow, quite a current.

  • Michael & JoAnne Gray
    Posted at 16:19h, 30 March Reply

    We are so enjoying your posts!

  • Jerry Bosch
    Posted at 16:58h, 30 March Reply

    Impressive diagnostic process resulting in a correct conclusion and a relatively easy fix. Very cool blog and thansk for sharing, Sam and crew!

  • Rick Kahn
    Posted at 18:06h, 30 March Reply

    I stayed at the resort on Iwojima island and it’s a beautiful place.

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