Actually the ramps are facing the proper way. The ramps faced in-land (meaning that the high-end of the ramp was inland with the low end out to the channel), so the ship would ride up it and tip over. Some also had mines on posts directly under the ramp so the weight of a boat going over it would press down on the ramp, touch the mine directly under it and detonate it.
In SPR they realized too late that the ramps were facing the wrong way, so they changed as many as they could given the time they had. But we've got pictures showing what the beach obstacles looked like from the original beaches. Check out the Spearheading D-Day book, page 16 (has a little diorama with an explanation of the ramp and the way they faced). Also, here's a link to some pics:
http://pages.zdnet.com/vancell/b26tailgunner/id19.html
There's 2 pics on there showing the ramps facing in-land.
------------------
-----------------------
Latuh fuh U,
Benson
benson@2015.com
"We don't introduce or cause bugs in the game, we merely find and bring to light the inadequacies within the code."
-regarding level designers