If you want dent-proof or all details on the construction, there is only one solution. Build the boat in wood and do it yourself <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Seriously, foam boats can dent and wood boats have their own issues. Dents are usually caused by point loads (knees, elbows etc), and you need a lot of fibers to stop the core from crushing. Treat the boat with respect and care for it, and dents will not be an issue. If you do get a dent despite being carful, fix it and pay the 100gram weight penalty of added epoxy and filler.