The Kwajalein MIA Project started out using a borrowed Imagenex Sportscan side-scan sonar, brought out each year for an average of two to four weeks by team member Bill Remick. Using that device, the team has found three MIA-related wrecks and part of a fourth.
However, there were significant drawbacks to this arrangement. The equipment brought by Remick each summer was on loan by a friend of Remick’s, leaving the team vulnerable. Should Remick suddenly have to return the equipment to his friend, the project would not have had any sonar equipment available to support their search efforts. Moreover, the equipment was between 15-20 years old, and its software was outdated and inadequate to support our team needs. The sonar also operated at a single low frequency and couldn’t provide the resolution needed to find some of the plane wrecks the Kwajalein MIA Project is looking for, especially ones that broke up on impact and were scattered into small pieces on the lagoon floor.
It became increasingly apparent that if we were to locate the remaining wrecks, the team needed its own, high-resolution, current-generation sonar equipment. We also needed access to that equipment year-round. In March 2015, the members of the KMP set out to raise the money to purchase its own sonar gear. That fundraising goal was achieved in August 2016, and the team now has its own side-scan sonar gear which is on Kwajalein the year-round, removing our dependence on outside support.
Marine Sonic SeaScan ARC Explorer side-scan sonar
In October 2016, the team purchased a brand new, state-of-the-art system from Marine Sonic. Our side-scan sonar is a dual-frequency 600/1200kHz sonar, which also incorporates adaptive-CHIRP technology for sharper imaging results. The sonar unit, called a “tow fish”, is towed on a cable behind a boat, and the imaging is displayed on a laptop computer.
Garmin echoMap 74dv chart plotter
Using leftover funds from the side-scan sonar purchase, we bought a chart plotter for the boat driver to use while driving the boat during sonar towing operations. The chart plotter displays the search grids and enables the driver to steer accurately while in the “lanes” within any given search grid.
The chart plotter came with a GT21-TM ‘downVu’ depth finder, which is attached to the back of the boat. The depth finder provides downward imaging to show the bottom contours directly under the boat. This gives advance warning of any obstructions, such as coral heads or shipwrecks, before the side-scan sonar hits anything underwater. This is critical because the side-scan sonar has no forward visibility, so it has no way to “see” approaching hazards.