i was at rock a hock couple years ago, they have some kinda washed out gravel ramp they allowed smaller boats to put in like jon boats...it was not best ramp but you can put in on lake side. Its just on other side of dam.
http://maps.google.com/maps?f=d&source=s_d&saddr=37.407862,-76.937262&daddr=1428+Outpost+Road,+VA+23089-5920+(Rockahock+Campground)&hl=en&geocode=%3BCdn2-HAKfsb4FU7ZOgIddP9p-yEEGjL7ec-gag&gl=us&mra=mift&mrsp=0&sz=18&sll=37.407545,-76.936703&sspn=0.002369,0.004061&ie=UTF8&t=h&z=18