I wanted to move my centre FCS fin around more like the old sliding boxes from the 70s/ 80s.
So the distance between tabs is about 3 in
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide001.jpg[/IMG]
and if you over lap 2 fins using a common position its ~ 5 in between front and rear tabs of the 2 fins
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide003a.jpg[/IMG]
Even if you use other fins with different bases its all about the same dims of 5 in
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide005a.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide004a.jpg[/IMG]
I figured out if theres a gap of 18 mm between 'positions' it works out simpler with the math, but theres no reason why a longer box couldnt provide more variations.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide007a.jpg[/IMG]
So Im investing a piece of plastic 5 in long , 6mm wide to make a slot 14mm deep for the fin base.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide008a.jpg[/IMG]
It will have 7 holes for 4 different positions for FCS and other base designs, but I havent tried them all.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide011a.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide012a.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide013a.jpg[/IMG]
I made a white wooden frame, rubbed car polish over the insides then balanced the grey plastic slot in position and poured an epoxy and CSM carbon fibre mix around it.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide016a.jpg[/IMG]
Took off the red tape and the whole block slid out the bottom of the wooden frame.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide018a.jpg[/IMG]
So the CF and plastic came out of the frame, its the same width as an FCS plug so it'll take screws from both sides.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide019a.jpg[/IMG]
And the plastic insert lifted out of the set resin and CF.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide020a.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide021a.jpg[/IMG]
The top surface is a little rough but I'll let it cure a bit more , clean it up and then drill the 7 holes at 18 mm spaces.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide022a.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/FCslide023a.jpg[/IMG]
If each hole is drilled from opposite sides ( 1/3/5/7 on the left and 2/4/6 on the right) it always works out that the fin has a screw going in from both sides for stability.
It gives 4 different positions over several inches for FCS fins but its even more variable with fins that have an elongated tab.