One lovely thing about taking some sort of stitching or needlework on
a cruise is that if you are in one of the lounges with your
needlework, people will stop by, say hello, and ask what you are
doing, so it's a great way to meet some very nice people. (If you are
reading a book they just walk on by.) Once when I was on the QE2
working on a bit of wholecloth quilting in the lounge near the casino,
a woman stopped and was so excited she could hardly contain herself.
It seems that she had lost a critical button on one of her formal
dresses and still had the button, but no sewing kit. She asked
whether she could borrow a needle and thread, and then dashed down to
her cabin to retrieve the dress and the button. The thread I had
didn't match at all, but the button was situated so that didn't
matter, and she was a very happy lady who even bought me a drink in
thanks.

So -- check the TSA rules about what you can and cannot take in your
carry-on. They are at http://www.tsa.gov. However, you should know
that the folks at the screening area can and do confiscate things
anyway! I have lost scissors, pair after pair, even though they ALL
met the formal guidelines, and even the little fold-ups, so now I
never take any scissors I care about. And I carry 2 pair -- one with
my stitching (occasionally confiscated) and one tossed into the bottom
of my purse with carkeys (never confiscated yet). Other than that, I
have never had any problems getting stitching things through security,
and that includes embroidery stuff, tatting stuff, knitting with
straight and circular needles, crochet, and hand-piecing and
wholecloth things for quilting.