To reduce thermal losses we follow the same principle that helps surviving in cold water: Put on layers of clothing.
In a first experimental approach the storage was enveloped in a conventional storage insulation: Two layers of 10cm each to simulate immobilized water. The foam should soak up with water to reach about the same density as water. This would simulate "immobilized" water around the storage. In this way convection should become irrelevant and the thermal conductivity of standing water will apply. Of course it is not expected to reach a similar thermal conductivity as for such an insulation used in dry state. The aim is to see, measure and verify the impact of standing water on the total losses of the storage.
To mount the foam on land, the storage is filled with air.
The storage is then brought to water, the air inside is replaced by water. Then left as it is overnight hoping that the insulation is soaking up water.
The insulation material did not soak up enough water to sink as we were hoping for. Instead, the material contained still sufficient air to induce uplifting forces as can be seen on the pictures. Other insulation materials are required.
Even if the insulation experiment did not work as expected, the effect of a wet insulation can be seen easily from the measured temperatures. The temperature of the wet insulated BILS is reaching easily more than 30°C with the same heating power than for the un-isolated BILS.