Internal Bouyancy of Surfskis

For skis without hatches where you could put a buoyancy bag does anyone know if surfskis remain buoyant or even neutral bouyancy if the space between the hull and deck fills completely with water? Is it going to sink like a stone to the bottom?

Or further if it is completely filled with water and the laminate is comprised such that the interstitial spaces become water logged?

Spec skis have a mandated foam stringer that will keep a flooded hull afloat, if not with enough buoyancy to support the weight of a seated paddler. (But at least the wreckage stays on the surface and is easier for a rescuer to spot than a swimmer.)

Fenn skis I know still retain the foam stringer but I do know that some other brands have done away with this and have no buoyancy at all.