need fin for 19th board

Question

fin box   I have a Bic board from the 1980s that I'm hoping to use this summer.  The fin broke in a move and I've lost it.  In looking for a replacement online, I can't tell if any modern fins will fit the fin box on my board.  I've attached a photo.  The slot is about 1cm wide and 3cm deep.  Thanks in advance for your help!

Answer
Hey Eric,

You need to look for a 'US Box' type fin. They are also called A Box and Chinook. Your old fin was probably about 8-10" but 12-18" would work better. You can buy new at many online windsurfing stores or find used on eBay. The link below is an example of a US Box type fin. The 'type' is based on the part of the fin that goes into the board.

http://www.windance.com/MFC-2K-Fin-19.7cm-US-Box-WSWF3767197US/

Hope this helps.
Keep on sailing,
Windlover