IKAK

IKAK: a small beacon for oyster rafts

We are developing a way to keep track of where oyster rafts are, using a small beacon fixed to the rafts and the smartphones of passing boats. IKAK sends out only its own ID number, and we never publish where boats or fishers have been.

For raft owners (fishing cooperatives, oyster farmers, local governments) and the people who run boats near the rafts

Talk to us about this use

The problem

Hiroshima Bay is dotted with oyster rafts. Rafts can drift away, and keeping track of which raft is where is not easy.

Oyster rafts lined up in front of an island

What we do

IKAK is a small beacon, fixed to a raft, that sends out its own ID number. We are developing a system in which, when the smartphone on a passing boat picks up the signal, the place and time it was received are recorded, and the raft’s position is worked out from those records. Rather than fitting every raft, we are considering putting beacons on rafts at key points and covering the wider area by satellite.

IKAK (a beacon for oyster rafts)

We are developing IKAK, a small beacon fixed to rafts. In the Town & Gown joint research of Kure City and Hiroshima University (October 2025 to August 2026), we were responsible for developing the device and the system. We do not distinguish which boat a signal came from.

IKAK holds no position of its own and sends out only its ID number. Its signal reaches only the area close to the raft, so a raft’s position is recorded only when the smartphone on a boat passing nearby picks it up.

Extending IKAK’s range (offshore buoys, other aquaculture, port facilities)

We are considering using links such as BLE Long Range, LoRa and LPWA to extend IKAK’s reach to a few kilometres, so it can also be used on offshore buoys, other aquaculture facilities and port facilities.

A calm sea and islands under a cloudy sky

Managing oyster rafts, and keeping track of rafts and debris that drift away

We are considering using IKAK’s ID numbers to tell rafts apart, so that even if a raft drifts away, its position is recorded whenever it passes a boat within the bay. We are also considering making the distribution of rafts available to oyster farmers and local government as basic information for managing the sea.

How it would be offered (app, data and beacons)

We are considering offering the app for a monthly fee that includes business liability insurance, and stating in the terms of use that the final decision on navigation rests with the person running the boat. We are also considering giving the beacons to fishing cooperatives free of charge, and selling the raft positions and other data gathered to other businesses.