I cannot answer your specific question regarding the OA. But as a boat builder, I have used a wide variety of core materials, including a number of different core materials including balsa, several varieties of foam products and honeycomb core such as Nida Core. The specific issue of the core turning to mush is only related to balsa wood core construction. The other cores may get wet if there is a point for the water to get in, but generally it has limited impact on the laminate strength. Case in point, in 2009 I had a customer with a Krogen Express. We found that large sections of the hull were wet, but only above the water. It turns out the builder ad not bedded the tank vents. Water had gotten into the core and thoroughly wetted it. WE took core samples and sent it to a lab for structural analysis. Results were good. WE them put a vacuum on the hull and managed to remove most of the water from the core. The boat is still fine and still cruising extensively.