I have a Nacra 5.5u - and my ball is about half an inch lower than that.

It took me a while to get used to stepping the mast on my boat. In my ignorance, I tried to mount the mast oriented vertically (not lying on its side), with more than a few demastings resulting (even snapped my captive pin in half!) My mast and ball escaped unscathed, but I can imagine the pressure from the mast being great enough to bend a longer post.

Good luck!

Aaron