I am looking at buying a 1996 450 SunDancer and have been trying to determine the hull construction too. I went back to SeaRay and asked them for a specific HIN#. I got a response that said the hull on a 450DA was solid fibreglass below the waterline and cored above the waterline. I questioned them because everyone says it is ALL cored. So, they sent me a spec drawing for the hum cross section and it showed solid FG below the waterline. I have attached the file they sent below. Hope this helps, but some long time owners say the entire hull is cored, so I guess the only way to be sure is to drill holes!
