Rick, dragging of the lagoon would be a laborious and major task and as you say unlikely to be approved by the Kiribati government. So have you considered another modern, non invasive alternative? I know you did a sidescan in 2010 but how about Lidar? Would the underwater (Bathymetric) version of Lidar give a different perspective view to the sidescan and a better chance of identifying those possible aircraft parts you mentioned ? I understand the Lidar penetration of the silt on the seabed/lagoon floor can be a few cm to 1 metre depending on the operating frequency chosen.
I looked at current Bathymetric Lidar capability (courtesy of google) and it appears there are many options available either to rent or buy. I have seen a figure as low as $7500 to purchase a Lidar set. Lidar can be operated from Aerial or Water borne drones, the latter being the better option I think in the Niku case
There are many companies I see on google offering their wares and services and to be clear I have absolutely no connection with the following company but I do think what they offer might be useful to ‘search the lagoon’ in a very short time period next time TIGHAR is on Niku.
Dave Williams
HÉLICÉO Bathymetric Drone with Lidar, Echosounder and Sonar Sidescan Capability, helps in monitoring ports, marinas, sea areas, rivers, creeks, lakes and ponds or lagoons.
Precision: Thanks to the different sensor choices we offer (echo sounder, 16 or 32 beams LiDAR, multiparameter probe, SONAR Side Scan), you can acquire mesh data from just a few centimeters up to a meter.
Video Link showing drone in use, in the water of a lagoon:
https://youtu.be/ianN3zbgaFkLink to company website for comprehensive versatility & capability information:
http://www.heliceo.com/en/produits-pour-geometres/superbathy-bathymetric-drone/