If it isn't long enough, and you need to make a longer one, it will have to be a size or two larger. I suggest you read my Wiring article on my web site.
The wire size by the way, is Japanese #10 which is roughly equivalent to our size 11 (if we had one). You'll need to go to #8 as a minimum depending on how long it will be. DON'T splice it! Remember, the voltage drop must be minimized for several reasons. They're explained in the above, and other articles on my site. Make sure you read VHF Options too.