The main benefit of the JRP is that on completion you will be provided with a positive skills assessment for general migration purposes. On this program, you must work for at least 12 months as a qualified Boat Builder.
Your employer will not need to sponsor your visa, as you will already be on the graduate visa. This will mean that you have a much higher chance of finding employment as it is very easy for the employer to hire you. You may find this video on the Job Ready Program helpful.