Do Click-In Fins Cause Leaks around your Fin Box?

[Bulky]

I love the convenience of click-in fins, but I've got a chronic leak around my fin box and I have to wonder if the forces created by putting them in and removing them each time I paddle are causing or contributing to the problem.  It's quick and easy but it does take a bit of force to push it in and then to pop it out.  I've probably got somewhere around 200 sessions on this board so that's 400 inserts/removals.  Even with the little bit of force it takes to lock/unlock the ball-catches, repeated over that many times could be causing cracks between the thin carbon skin and the box.

Did a few backyard repairs and then got it fixed professionally about 2months ago.  This morning, I noticed the dreaded bubbles when I was packing up my gear.

Any theories out there in support or refutation of this?

[TallDude]

I think what happens is the little spring loaded balls in the fin (if that's the type of snap in you have) probably get corroded. Just it takes more force to get the fin to seat down. If the balls don't move in, the fin box will flex out. When that happens, the glass bond is going to be broken. You may have fixed the fin box before, but the real problem could be your fin. Can you replace the spring loaded balls in the fin? Or is it the polyurethane roller type ?

[Area 10]

Hmm... This was always my worry about click-in fins, especially for those of is who live in cold wet climates where metal parts might stay wet between sessions and corrode. The tolerances for click-in fins must be pretty tight, and fin box installs can differ quite a bit even between two supposedly identical boards. So maybe your fin is actually a bit too tight for the box?

Incidentally, I notice that some retailers are warning that the new FCS2 click-in fins (e.g. their Fat Boy) are only compatible with boards fitted with the FCS II system. This rather limits their appeal for SUP perhaps because I don't know how many brands/models currently use FCS2 longboard boxes. Maybe this hints at the degree of compatibility between longboard box and fin required for click-in systems to work well?

[yugi]

^ yet another reason to get a custom board!

[Area 10]

^ yet another reason to get a custom board!

Well, I just did, actually. A 16x24.5" fixed fin downwind board. But it has a Futures box. I don't think many of us realised that the FCS click-in fins would only work with a FCS2 finbox (or could be guaranteed only to work with...). I was only just told.

[supuk]

according to the fmcs site they should work with most fin boxes. There is not a fcsii specific longboard box just a fcs standard longboard box that i have seen listed.  I have not yet had one to try but obviously it will put more stress on the box and the board around it and may cause problems over time in some situations. As normal i have been thinking about this hole click in fin thing and fin boxes for sups and have quite a few ideas that i hope to explore as there are definitely thing to be improved on!

http://www.surffcs.com.au/community-story/community-blog/2016/07/20/how-to-fcs-tool-less-longboard-fins

[yugi]

^ yet another reason to get a custom board!

Well, I just did, actually. A 16x24.5" fixed fin downwind board.
...

Cool! Enjoy.
You've have a lot of DW boards and gnarly conditions. I look forward to hear feedback on that one.

[Bean]

Is the box set in high density foam Bulky?  If not, maybe consider setting it in 3/8"-1/2" Divinycell on the next repair.

[mrbig]

FCS II click in surf fins only work in FCS II boxes.

The FCS Longboard click ins will work in both US and Bahne style boxes..Ditto for their SUP race fins.

Have had no issues with leaks or other problems with the surf fins. I can see the potential for stress with the Longboard and Sup fins..No personal experience with those however, so I will not do the hypothetical dance!

Update flash! Called FCS HQ and asked if they are marketing and/or selling a longboard/sup box to go with their click in LB/SUP fins.

Will pass on the response..

[Bulky]

Is the box set in high density foam Bulky?  If not, maybe consider setting it in 3/8"-1/2" Divinycell on the next repair.

Thanks, Bean.  I might consider that.  I also just wonder if there's a point where things just get brittle with age. 

TallDude--they are metal ball catches and they do get rusty and gunky but still move.  I thing what you're saying about fin box flexing is true even if everything is working right..

Last time I had it repaired, I asked them to paint a big white square around the fin box white so I could see things clearly.  A few weeks I saw a pretty clear hairline outlining the front edge of the finbox.  Now I've got bubbles on the back.

Like Bean says, I think it's going to take pulling it out and setting the box in a good bed of divinycell.

[Area 10]

FCS II click in surf fins only work in FCS II boxes.

The FCS Longboard click ins will work in both US and Bahne style boxes..Ditto for their SUP race fins.

Have had no issues with leaks or other problems with the surf fins. I can see the potential for stress with the Longboard and Sup fins..No personal experience with those however, so I will not do the hypothetical dance!

Update flash! Called FCS HQ and asked if they are marketing and/or selling a longboard/sup box to go with their click in LB/SUP fins.

Will pass on the response..

Thanks for checking. It seems that some retailers have mistakenly applied the same cautionary message to the longboard fins as they use for the other surf fins (ie. FCS2 require FCS2 boxes).

I'll have to try one and see how tight it is in a standard US box. Common sense kinda says that it will have to be pretty tight though. If you lost a fin on a big downwinder you'd be in a mess of trouble.

[Bean]

For sure Bulky, plastic finboxes get brittle over time; most of the failures I've seen have actually been cracked boxes.

One thing to remember about finboxes on SUP's vs traditional boards is that the SUP's tend to be thicker overall including at the tail.  So, while the finbox on a traditional longboard might actually be getting some support by virtue of its proximity to the deck, that same finbox installed on a SUP could have more than an inch of foam between it and the top skin.

To limit the movement at the fin box you might even wrap the finbox with carbon fiber instead of glass.

[mrbig]

Area 10,

As we suspected there is not a special box to go with the new click in LB/SUP fin.

Given my dremel grinding adventures to get the fins from the windsurfing lineage to fit, and never perfectly I might add, I am curious if the FCS click ins are optimized for the US Box, or the Bahne Box.

There was a very detailed and comprehensive explanation of the differences posted here a while back. Methinks I will continue with my plate and screw. I cleverly  managed to damage a box by using a plate and screw from the,Starby (and others of course) in the other box! Oops! Leaky! NFG!

[Area 10]

Yeah, hard luck, the Starboard boxes require a longer screw than most so if you use it in a standard Fins Unlimited style box you can break it.

It's fantastically annoying that there are so many different finbox standards. And the variety of boxes in a SUPs actually seems to be increasing rather than converging on one standard, as I'd hoped would happen.

[mrbig]

My years of surfing experience did not help a bit!

Insult to injury - after grinding the damn hump off - the screw becomes waaay to long.
Interference fit! Hole in box. Now I know..