I have read endless posts on packing and what to wear and not wear, take or not take, but only one on packing a "long scarf". I did see don't bring a hat, because the wind could take it away, so putting all that together, I get the impression that maybe standing at the rail could be a little breezy. Not being a hat sort of person, but also probably not going to cut my long hair, is a scarf a good alternative to keeping your hair out of your face, and providing a bit of warmth? Sure isn't something I would have thought about packing, but I reckon it will be added to the list.
If you plan on being out on deck, you need a knit hat. Tuck up your hair, absolutely necessary, unless you are good at likeing knots. The scarf takes up little room, if you like using scarves, bring it.