Photo/Illutration The salvaged Kazu I pleasure boat is moved to dry land at the Port of Abashiri in Hokkaido on June 1. (Naoko Kawamura)

A hole in the bulkhead of the salvaged Kazu I pleasure boat may help to explain the late April sinking of the vessel off eastern Hokkaido with 26 people on board, none of whom survived, authorities said.

Holes were cut into the three bulkheads under the deck to allow crew members to crawl through the spaces, according to an individual with knowledge of the boat’s interior.

Bulkheads are installed to strengthen a boat’s structure and stop seawater from entering the separate compartments.

Two of the bulkheads separated the Kazu I’s engine compartment from both the bow and the rudder operating compartment at the stern.

An inspection by the Japan Craft Inspection Organization (JCI) in April 2021 found holes measuring a few dozen centimeters in the bulkheads in front and back of the engine compartment, according to the transport ministry.

JCI inspectors ordered the holes sealed as a fire prevention measure. Subsequent checks in June 2021 and April 2022 confirmed the work had been done.

However, transport ministry officials said they were not told about a hole toward the bow of the boat because there was no requirement for the JCI to inspect that particular bulkhead.

After the Kazu I was raised from the seabed off the Shiretoko Peninsula and placed on dry land, a hole was confirmed in one of the bulkheads.

While the holes in the bulkheads in the front and back of the engine room were sealed, they were not sufficiently airtight, leaving open the possibility seawater might have leaked into the vessel during the rough seas the skipper reported encountering when it sank April 23.

It also emerged that when the Kazu I was found on the seabed, the cover of the hatch on the bow deck had detached. It was later found near the wreck.

If the hatch was open at the time of the sinking, or if cracks developed in the bow of the boat, water could easily have flooded the vessel.

Because of the weakness of the sealed holes in the two rear bulkheads, seawater might have also flowed into the engine room. That would help explain an emergency call from the Kazu I to the Japan Coast Guard on April 23 that indicated the bow was taking on water, the boat was sinking and the battery had died.

A call from the skipper to his head office said the bow was tilting at a 30-degree angle.

Coast Guard officials are using those calls, as well as a check of the boat’s structure, to piece together how the tragedy unfolded.

(This article was written by Kaho Matsuda, Masafumi Kamimura and Masanori Isobe.)

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