I'm half Scottish, as in Mom came over on the boat, literally. So we've always had quality sweaters around, usually oiled via St. Andrews' Woolen Mills (yep, we visited a lot, even the famous golf course). And while they definitely are nice, any more, they're reserved for land duties. As fleece (especially), and woven wool is a LOT more durable, in addition to being warmer. Plus, the latter two aren't finicky about being wet. Meaning that they don't get all stretched out of shape if soaked. Plus; you can machine wash them, wring them out by hand, & even tumble dry most of them. Oh, & they're a LOT more abrasion resistant than knitted sweaters as well.
My favorite is my (two) Patagonia Retro Cardigans, which sadly are no longer made. But they're 3/4"+ thick fleece, & warmer than anything I've ever owned aside from a full on Winter parka.
Said company still makes some super heavy weight fleece, & if you call the Dillon, MT outlet store, sometimes you can find items dirt cheap
. Ditto on visiting any of their other outlet stores.
Though likely the best options are waterproof fleece, & waterproof wool. And no those aren't typo's. Look at stuff in places like Cabela's, Filson, etc. Plus, as of last check, Woolrich made a few, nice, waterproof wool coats & jackets.
And as a perk, the items/manufacturers in this last paragraph tend to price
their items a lot more reasonably than say, Patagonia, or anything with a nautical association. The one exception to this being Filson.
One more perk about fleece. If/when it gets wet during a watch, once you get below decks, you can just wring it out good, & pull it into your sleeping bag with you. And on most occasions it'll be dry by the time your next watch.
Although, sadly, unlike wool (socks, long johns, & pull overs, etc.) you really can't put it into the microwave to get it toasty warm right before you go on watch.
But with everything I've listed, you'll get sick of having them around before you wear them out, knock on wood.