replacing a long fin box with FCS or something similar


Its been a long time since I’ve been on here and even longer since I’ve done any work with boards but I do have a little project I need help with.

I recently picked up a very retro 5’10" single fin. It surfs good and it is a lot of fun but I am curious to try it as a 3 fin.

I want to rip out the fin box and install some FCS or probox or something similar.


What is the best way to cleanly get the box out.  Should I route around it and pull a large clean section out.

What is the best material to fill in the hole. I am thinking of plugging the hole with a piece of balsa or another piece of PU foam and then glassing over it before installing FCS as usual.


Any advice would be really appreciated. 



true ames has smaller center fins 3-6" range

it would a less intensive way to see if you like it,

then all you would have to do is add the fcs plugs..

and you might want to have 3 plugs so you can use

those 3 plug fish fins..and gives you leway with positioning

of  side thruster fins...

..hope this helps

You can purchase an FCS longboard box adapter so you can simply insert your FCS centre fin into your exsisting box.

As DANSAN suggests you'd still have to install the rail plugs but that way you wouldn't be doing uneccesary work. You'd also be able to still experiment with single fins or 2 + 1 setups...

heres a link off the FCS website (but this one's for the UK)...should be able to find them where ever you are:



hey brian,

hows things?

are you still in japan?


Hey Paul.

Yeah… Still in Japan. Still in the snowy mountains away from the surf