So you want to knit a sheep...
And the knitter of the sheep:
Go to Cat Carlisle's blog for directions; she also made (and has directions for) a couple of versions of Jack Aubrey's uniform (that's her modelling it in 2007), and photos from her visit to the Surprise in San Diego. She is another cool Cat. :D Link:
I suspect her later RN uniform is about 10 pounds lighter than the Admiral's--it is about 40 years later, too.