Thanks all for the info, and espec., you, Ray for the in depth reply. I think we met at the Samson launch last summer when you arrived with your camper to take a whack at them.
I think I know what happened. I went under the trailer and after having rolled the boat back 6" and found a depression in the bottom where the bottom rests on the main center roller. That is where the 1" crack is and most likely was created by concentrated boat weight stress. So, I used a jack and raised the double rollers on both sides, up the slope from the main center roller, so they really helped carry the weight. Apparently the roller frames had slipped and let the rollers loose contact with the hull.
I think the riveted plate at this position would solve my problem, but hate to have to tear up the carpet and floor to accomplish. I know the stop drill process etc.
Do you know anyone who could be trusted to do this correctly, besides ME ? and not render me destitute ? Thanks again