The collision with the island just disabled a couple of crew and tore off the mast, thus they lost radio comms and lighting; but the boat did not sink there, as there were no heavy parts found in the area... no motor or keel. The boat then drifted away from the island, while sinking, and without radio and lights, and then was run over by some ship, finishing it off and shredding the FRP into tiny pieces.

This is the only way that all the evidence fits together... the GPS track, no heavy bits found near the island, no SOS, and all the shredded bits found later.