First of all, I'm not knitting a genuine gansey. I just like the way Eriskey ganseys are designed, so I've been making fake ones for years. They are easy, interesting and lots of fun to do. I hope you will try this out, or if not, at least get some idea of the process.
Pick my yarn and needles
I don't buy a pattern and then buy yarn accordingly; instead I pick out yarn, and work with that. For Emily's gansey, I bought Rowan Pure Wool DK ( 50 gm, approx 137 yards (125 m) I had to special order this, so I have a bag of 10 skeins, but I think I'll only need 8, but we'll see. I usually rely on the shop owner to give me an idea of how many skeins a sweater needs. I work a 36" sweater, so I use that as my source for size. That is Emily's size also, although she wants the back to be a tad narrower. I'll start of with 36" and then make adjustments in the back.
For first time sweater designers, I would play around with needles. If you knit tightly, you just might want that #6 needle or even a #7. Since I'm such a loose knitter, I debated on using either a 4 or 5, and I decided that whichever swatch looked the nicest, that would be my needle. I ended up using a 4 with a gauge of 5 sts/inch.
Why stockinette? Many ganseys have knit/purl patterns, and stockinette is pretty close to the gauge I would get. I know that my purl rows are a tiny bit looser than my knit rows. When I knit in the round, I have to take that into consideration since there are no purl rows in stockinette in the round. However, I use knit/purl patterns in the body of my ganseys, and my gauge is accurate in the round without me having to compensate for no purl rows because of those purl sts. (If I were doing cables and/or lace, this wouldn't work because those sts really affect gauge.) Does this make any sense? If not, comment, and I'll write back.
For you, I would do a stockinette swatch in the round. If you don't like how it drapes or feels, change needle size. Yes, it is a pain to do this, but you need to make swatches for a commercial sweater, too. Anyhow, it'll give you a chance to get to know the yarn. Make it a good 4 inches long, and measure over 4 inches to get an accurate gauge. Write it down someplace so that you have a record of it. Why? Suppose you want to knit the sleeves just in stockinette, this way you have a gauge already done. When you are finished, take a picture of it, and then rip it out. Yep, frogging is part of knitting.
Here's how I keep write things down. Graph paper because I chart on graph paper, and this way the entire design is on a couple of sheets.
You can use your computer, a charting program, or plain old graph paper. A very good program is Intwined Pattern Studio You can google this on the web. I use graph paper because it is so user friendly. You make a mistake, you erase, but I've also used Intwined, and it's very good.
OK, that's enough for today. Next post will be pattern choosing and swatches.