Probox fin system

New to the site and looks like a wealth of knowledge here…Will be building a modern style simmons soon and look forward to some advice…

Regarding probox…I just don’t surf tri fins all that well…I guess I like the looser feel of a quad and decided to install quad boxes in my v2 shortboard. Really like this system, but my only concern is the gap when using fcs fins. Really didn’t think about it until after the install…Iam an average surfer at best and will probably notice no difference…just a mental thing…not sure if there is something like a filler that fcs puts into there new system when using older fcs style fins…in fact wonder if they would work? I guess I could make more work and use composites and cut them down to fit in the box or cut and fill my future quads to fit the box, but then I lose one of the attributes that make the probox such a cool alternative…hoping to go the filler route or maybe buy probox fins…I like the idea of changing cant and able to move the fin forward or backward…btw, the system was incredibly easy to install…tho when I took the router to the board, I was a tad nervous.

 Gonna start a build here shortly and plan on using the probox system.


do you have a pic? I can’t think of a gap

Yeah I am wondering (as Chrisp) ;  What you are referring to??  I’ve never heard anyone say they had a problem with a sloppy fit when using FCS  two tab fins in ProBox.  Pics??  Lowel 

The gap is located in front and rear of tab and between the tabs…depending where iam sliding the fcs fin…like I said probably no big deal…the gap is noticeable in the front when I slide the fin all the way in the back of the box.  Really can’t see much of a gap elsewhere cause the fin covers the majority of the slot.


no it’s a tight fit…I think iam making a mountain out of a mole hill.

OK.  I gotcha.   Fill it with a little surf wax.

mountain out of a molehill for sure. to the n-th degree.

Are you surfing leashless?

Just thought maybe there was a filler available similar to the new fcs system with the old fins…it actually looks those fillers may work…When slid back, there is a gap…I guess I just like a cleaner look…but certainly not a deal breaker…did notice that I acquired some small air bubbles when I went to sand it…anyway to avoid that next time?




Regarding the bubbles, I used to babysit the boxes with a toothpic and pop the bubbles.

If there were any voids after sanding, I would mix up a tiny ammount of resin and fill the little holes again, using a toothpic to put the resin in the holes.

My question about surfing leashless was serious though. If we are talking drag, a leash is probably the worst thing that we add to our boards. Tailpads are terrible too when the board is on rail.

I know it’s no big deal…it’s just more of a cosmetic and mental thing…I even put the fillers in on the ones I don’t use…I do surf with leashes…now I gotta rethink my leashes…jk.

thanks for the input on bubbles…gonna fill those voids up and watch more closely next time…looking forward to my first build. 

The tooth pick thing made me think of the “rollers” that boat builders use.  Pretty amazing the way they take a roller with teeth to all the corners and air pockets.

Just shave the tab down a bit. I find that a lot of fins - singles, thrusters, quads from various manufacturers all need a little tailoring to fit a box/plug just right.