They are supposed to convince an employer that you can do his job though you have experience in a different function or a different industry or both. This has worked through at least 3 decades and 3 recessions up to the dot.com bust and 2001 recession. Then the game started changing.
Back story first. What are transferable skills? They are a list of action verbs that best describe your abilities. Google it or look in Wikipedia. You will find lists galore or better still buy Parachute as it is the absolute best source. It really helps to be able to pinpoint exactly which skills are your best ones that you love and excel at using. It used to be that well a articulated set of skills were enough to convince an employer in an interview and on a resume that you were a good fit for the position. Or at least worth consideration.
The stakes are raised, the options are narrowed, the doors are closing. Or are they? Not if you lead with the relationship and not the resume. People hire people they like or get to like by meeting them informally not in an interview situation. If you approach your job search in that fashion then your resume won't end up in some recruiter's file 13 (trash bin).
That means you don't bare your soul and entire resume on social networking profiles like Linkedin.com, but rather use the sites to exhibit a well crafted and branded advertisement about who you are instead. People expect you to have profiles online so manage the message and talk about yourself in a way that minimizes the transition or career change you are trying to make. When you lead with the relationship then you can speak to your knowledge about the sector.
You can demonstrate your experience by being able to "talk shop" about the sector and industry. That means you do in-depth research to be able to demonstrate your knowledgeable competency. Being able to drop names, mention studies, refer to articles, speak about key products and talk about trends makes you "one of the group". The effort it takes to explain and justify how your skills transfer doesn't measure up in comparison to the impression you can make just "talking shop".
I have seen professionals hired without ever providing a resume. They finally filled out the employment application during the interview process. Leading with the relationship allows you to talk about your accomplishments and the sector you are trying to break into in a way that makes the impression that you can do the job. It is the best tactic to use to skip past your lack of actual experience in a specific industry.