We provide sand boards, but snowboarders should bring there boards and boots we will provide sand wax before each run that will make the snowboards just as fast as the sand boards, but not the "Black Board"
The design of the snow board is fine for sand. The composite is sturdy enough. There are some conditions that allow the snow board to reach reasonably good speeds. One condition is extreme angles. If you are able to find a very steep dune face that is also accessible to you by foot you could ride that snow board at speeds that will satisfy. Of course, when the face is steep enough you could ride almost anything and it will fly, especially on the dunes here in Egypt.  Plus riding your board on the sand will get all those scratches off your board all you need to do when you get home is wax it and hit the snow.