Mrs Burris asked me to explain how I adjusted the fit of the two Louisa Harding garments from my last post for my broad shoulders, so here goes...
I have broad shoulders and largish upper arms from work and although I have a bust, my shoulder measurement is greater than my bust, but about the same as my hips. I used to think I was a pear shape (based on my bust/hip ratio), but nothing recommended for a pear shaped figure looked any good on me. When I started sewing my own clothes, I had to pay more attention to fit than I did on my knits (which are pretty forgiving) and I worked out how to adjust for my figure which is somewhere between a hourglass, an inverted triangle and a column. I'm also tall for my size with long arms, a shortish waist and a very broad rib cage (now you know why I make my own clothes), so I always have to fiddle with the length as well as the width.
It's the same as adjusting the fit of a multi-sized sewing pattern, but there is one caveat, you have to have the correct tension/gauge for the pattern, or know how your tension/gauge varies from the pattern, so that you can make the calculations. I generally think there's often a bit too much ease in knitting patterns, and that fitted garments look better on me than loose, but you also need to be aware of how much give - or not - your yarn has.
I use my tension/gauge to measure length, so if I'm knitting a DK with a tension/gauge of 30 rows to 10 cm and I want to knit an arm scythe (arm hole) that is 20 cm I knit 60 rows from the first cast off row.
And I always knit from the bottom up and generally in pieces as I think the seams give you structure (just as in sewing) and stop the garment from twisting too much. I use mattress stitch to sew up all my seams; with practise it's easy and gives a great finish.
Louisa Harding's Breaker (from Ondine)
I take my actual bust size (91cm) as the size I use for the pattern. Working from the pattern schematic diagram I start with the finished size that is the closest to my bust size plus the amount of ease I want (not necessarily what the designer recommends). In the case of Breaker I chose a UK size 10 which is just 1cm smaller than my bust.
I add length to the body (below the underarm) as required. The schematic can help you here also. Deduct the arm scythe measurement for your size from the overall length to calculate the length under the arm and work out where it's going to finish on your body. For my body, finishing somewhere around my hip bone is ideal. If, like me, you need the extra length below your waist (I have a short waist), start your waist shaping later, if you have a long waist, start your waist shaping as directed by the pattern, but put extra rows between the increases.
Once I get to the underarm decreases I reduce the amount I cast off and decrease to blend the garment up a size or two to get the width across the shoulders I need. For Breaker I cast off 3 and then 3 stitches and then did the number of decreases to give me a width across for the next size, UK size 12. I then followed the pattern direction for that size from there, knitting my arm scythe to 20 cm (to fit my upper arms without cutting off the circulation).
NB. If you have a large bust you won't be able to do this as you need the extra material under the arms for your bust. My suggestion would be to do more increases from the waist so that you arrive at the underarm at the larger size.
You need to adjust your sleeve shaping accordingly. Because of my long arms (36 cm comes just over my elbows) I knit extra rows (12 instead of 10) between my sleeve increases to make the sleeves longer (if you have short arms, just knit fewer rows between increases) and if I think the sleeve is going to be tight (work out the width of the sleeve using the pattern tension and the number of stitches after all the increases have been worked) I often add an increase or two (I didn't need to do that for Breaker). I then do the same decreases I did at the underarm on the body and knit the sleeve cap following the pattern for the size that is closest to the the number of stitches I have (usually the largest) to fit my larger sleeve scythe.
For Louisa Harding's Reef (also from Ondine), which is a raglan sleeved as opposed to set in sleeves, I started with a UK size 12, lengthened the body by three rib repeats before the colour change, cast off two less stitches under the arm on each piece and rewrote the decreases to one decrease row every third row, nine times, plus two rows. That brought me to a UK size 14-16 which was great up my shoulders, but no good for the fit around my neck. So I knitted two more repeats of the rib so that it didn't fall of my shoulders, changing to the smaller needles half way through and decreasing twice (k3, p2tog, k3 p2togtbl) to reduce the number of stitches back closer to a UK size 12.
Looking at Reef in the photos, it could have been tighter (as in the pattern photographs), but as 85% of the yarn is cotton which has little give, I didn't want it to be too restricting under the arms, and it's super comfy as it is (I'm wearing it now).
Mrs Burris, I hope this helps...there are details of the alterations I make to most of the patterns I knit on Ravely.