Just retrieved my board from the gf's and am wondering what type of fin I need.

It's a Fanatic Bee of some sort if that helps.

Am I right in assuming that I've lost the bolt thing to hold it in?

What would you recommend for a 140ish litre board about 290cm long.

Also are there any places in melbourne where I can get trim box fins, was hoping to get out this weekend but that may not be possible anymore.

Definitely a trim box. Recognize the board. 137 litre Fanatic Bee. Used to be bright green before a mate of mine went mad with the spray paint. The two plastic blocks slide in the track so that you can position the fin forward or back. Originally there were 3 but a rock at Stanley removed one. Had a lot of fun with that board. Good for light wind and learning, only problem I had was that you couldn't push it too hard in the gybe or else it would go sideways.

www.seabreeze.com.au/Classifieds/Windsurfing-Accessories/~vedyw/Ht-Race-12.aspx?_page=1&search=gvyj2BKrnvnoSv1T0pAJr2rwTMMvsUzj

www.seabreeze.com.au/Classifieds/Windsurfing-Accessories/~vedy5/Bic-Freeride-31.aspx?_page=1&search=gvyj2BKrnvnoSv1T0pAJr2rwTMMvsUzj

www.seabreeze.com.au/Classifieds/Windsurfing-Accessories/~v33d1/Slalom-Up-29.aspx?_page=1&search=gvyj2BKrnvnoSv1T0pAJr2rwTMMvsUzj

Mmeyer said..
The smallest trimbox fin SHQ has is a 42cm, is this too big for my setup given i'll be mostly using the 5.5m sail?

Well that's it then. Your windsurfing comeback is over before it restarted!
Oh, wait, you could always cut 10cm off that fin with a hacksaw and it would be about right!