HI!
This is my first post. I have been reading this forum for months. I would like to knit the Life Aquatic Beanie From knitting pattern central the instructions suggest to cable cast. Would it matter if I used longtail? Thank You in advance for any information.
Koleen
Probably not. The cable cast on is good for ribbing, but in my experience, the cast on is usually just a personal preference.
And my #1 rule in knitting is that I make my own rules. So, do what you want. 
Welcome to Knitting Help!
There are many cast-on methods. Personal choice for me is long-tail but there are instances where you have to use the method called for in the pattern. This is an instance of your choice.:woohoo:
I prefer to use the cable cast on all the time. I think it looks nicer.
candice
Not familiar with the pattern but the cable CO is known for its sturdiness. Perhaps that’s what the designer was going for. Certain COs are more elastic than others. My default CO is LT but it’s not always the best for certain projects.
cam
Unless I need to do a provisional CO for something, I always use Long Tail.