Layers are the way to go.
I boarded wearing a tee short & long sleeve blouse under a cotton cardigan. The sweater came off once on board. The cardigan was later worn over my shoulders at dinner when they turned the AC up too high.
I brought a few sweaters like that. Make sure that they can be worn over your more summery clothes.
You do want to bring your winter coat -- you will need it for embarking & disembarking. You may also want to wear it if you go on deck for sail away. Sturdy shoes are a must for that.