Directional Fins/Fin Box Durability

Pete · Since 29 Oct 2007 844 Posts Opinionated

The question about durable directional boards got me thinking about what seems to be the weakest point on directionals that I have seen, that being fins and fin boxes. Everyone that I know that has ridden boards with either Future or FCS fin boxes, have broken, cracked and plain ripped out several boxes on several different boards.

These fin boxes were designed for surf boards, and quite simply, kiting puts far more pressure on fins and fin boxes than surfing does. Personally, every single board that I have that has future boxes on it (five), have cracks around them. I've ripped out three of them, and have had to have them repaired.

Don't even get me started on the FCS boxes. I've seen so many of those fail, I can't even begin with all of them. Why anyone would use these on a kiteboard, I have no idea.

Contrasting to this are the mini-tuttle boxes. Slingshot used to use these on all of their boards, and they are bombproof. Not one has ever come close to failure, on the two boards I have these fin boxes on, and several other buddies boards that have them as well. I have seen the fins worn down to the point that they have to be replaced, from running them up on the sand, and not a crack to be seen.

Question is, why aren't more board manufacturers using the mini-tuttle boxes? I'll counter this, with what I know the answer will be. Limited availibility and choices. This was the same argument against 29" wheels in mountain biking, limited rim and tire choices. Look where that has gone. It's a non-issue, due to the fact that they are everywhere now. The same will likely happen with 650b wheels.

Point is, if everyone started using the mini-tuttles, there will be more and more options, more availability, and a non issue getting them. Slingshot switched from Mini-Tuttles in 2011, to FCS in 2012. One of the strongest systems, to one of the weakest. I don't get it.

Someone please enlighten me.

Hein · Since 08 Mar 2005 1314 Posts Possessed

ProBox
Larry knows

Pete · Since 29 Oct 2007 844 Posts Opinionated

I guess it's just me that has fin durability issues, only one inebrieted response in two days.

Hein · Since 08 Mar 2005 1314 Posts Possessed

You can put any FCS fin into a ProBox. Probox is structurally similar to the mini Tuttle with the added benefit of being able to tune the cant angle AND move the fin fore/aft up to 1/2 inch. Those two things can make a big difference in performance.

I've run fins into rocks along the shore at Rufus and totally chundered the fin with no damage to the box or board. I do set them in a higher density foam plug which goes to the deck. I doubt you'll get the industry to standardize on a fin box. But if you are getting a custom, have your shaper contact Larry Allison. Tell him I sent you.

http://www.proboxhawaii.com/

nickdward · Since 11 Aug 2008 130 Posts Seattle Stoked

Pro boxes work great. Adjustable fore/aft placement is key on any system, and the adjustable cant is nice for home builders or tinkerers. Plus use your same FCS fins.

However, aside from the adjustability, FCS fusion boxes can be just as strong...all depends on the install. Fusion boxes go under the glass and have high density foam inserts built in.

I've switched from doing pro box to fcs fusion on my boards. Mostly because theyre lighter...The pro box cant adjustment is redundant onve you figure out what works well for certain boards, and glassing over the boxes is the best way to make sure it's not going anywhere.

As for fins, I'd rather have my fin break off than have to repair a fin box. I use fcs pc or pg fins mostly. The pc fins are much more delicate than plastic fins, but much better performance

nickdward · Since 11 Aug 2008 130 Posts Seattle Stoked

Mini tuttle boxes the fin isnt going anywhere and if you run into something......you're installing a new box

Hein · Since 08 Mar 2005 1314 Posts Possessed

I modified the Probox install so I could glass over them. Actually installed the box and then finish machined the bottom of the board taking off a little (15 thousands iirc) of the box. Then laminated the whole board in a vac bag in one hit. I'm sure that makes the system a little stronger.

Forgot about the fusion box which is a good system. But I like the cant and position adjustment. There is just no way to totally predict the feel of a board so the ability to tune is nice and can accommodate different riding styles and conditions.

Obviously not an EPS core here but you get the idea.

Pete · Since 29 Oct 2007 844 Posts Opinionated

Gman · Since 11 Feb 2006 4911 Posts Portland Unstrapped

we've been real happy with the probox and fcs fins - just don't run over the board with a jet ski (fairly easy fix)

Hein · Since 08 Mar 2005 1314 Posts Possessed

That probably wouldn't happen if you set them in higher density foam that goes to the deck. Or at least post them to the deck with a resin/glass slurry.

But I also see bubbles in the resin under the box. That is caused by an exothermic reaction when the resin is allowed too become too hot while curing. That likely melted the foam and ruined the mechanical connection of the box to the core.

The problem is that the heat can't escape due to it being insulated by the core. That's a common booboo that can easily be avoided. Always use slow cure resin when setting boxes. Your shaper/glasser needs to gain a better understanding of how resin cures and how to avoid those problems.

The desired failure mode is that the fin tabs break off.