Surfboards Australia Single Fin

Had an old single fin given to me. It’s a 6’ 2" Surfboards Australia. I bought a Hobie Liddle fin for it but have run into some trouble.

The stock fin plate seems impossible to remove from the box. The screw takes a metric Allen key. I can’t tight then enough to hold the Hobie fin secure. Any suggestions?

By “secure” are you saying the fin screw is actually coming out, or are you saying the fin base is wobbling side to side?   Because if its the latter you can wrap the base in some wet/dry sandpaper before inserting it into the fin box.  You’re basically making the base of the fin fatter and giving it some grip in the box.   This will make the fin fit more tightly.   

I’ve surfed singlefins where the fin was so tight in the box that I didn’t even need a screw.   

You should be able to use most any type of bolt for the fin plate, as long as it’s the right thread pitch.

A loose fin can be corrected in many ways, temporary and permanent. I just lay on some sanding resin to both side of the fin, then sand as needed.

You may in fact have a fake made in China. The original SA label was made by Gordon and Smith under license in the US. They disappeared by 1971. Any board newer than  that is a fake made in China.

Wound up finding a replacement bolt and shimmed the new (old) flex fin with a piece of plastic bottle.  Thanks for the ideas, folks.