I know, but really, sex is not about the erection. Sex should be about the feelings, the touching, the sharing, the exploration, and the pleasing. Lets face it, a women does not "need" an erection to get off. Don't believe me, look at lesbian porn...
What is needed for great sex is a connection and communication. We all know that you can buy pricks at any adult store or even make one out of a cucumber. So now that I have deflated all your male egos. Oh and all the "but its the motion of the ocean" comments are bull...
How do you get around that (and this goes for everyone) is to talk and find out what makes your SO tick, floats their boat, or any other analogy. Now that communication can be as simple as a pick up line and "Lets go back to my place to fuck!" Can that lead to great sex, yes.
Because everyone gets all hung up on communication being spoken. Communication is anything that can get your message across. You can tell you partner that you like what they are doing by saying "I like that baby" just as well as a head thrown back, heavy breathing, and a guttural moan from deep within.
Reading your SO's body language (Just ask Ariel). But thats a blog for another day.
Keep it kinky!
-Haven De Lancret