Just in from a session were i snapped my side FCS fin clean off- at the inserts, plugs fine, so i don't have to refit. I'd laid an extra layer of glass over the plugs so that probably help save them
What fins do you use? Some stonger than others?
Am working on driving pretty hard upwind, so was pushing it pretty hard. Didn't have the spares in the car, so kept going - slippery as f*ck, but sure teaches you to hold a rail
Hey Gordknot,
All FCS fins are crap in that they'll snap off with any decent knock. The M5's are a great fin, one of my faves for grip and holding power.
I now use Future fins where possible as their base system is heaps stronger.
I have a heap of right hand G5's and M5's coz we always snap L/H thrusters.
FCS - Bah! 
KH
) on the same board, they were futures and the boxes are still fine.
fins are the most vulnerable part of the whole board and open to all kinds of severe stress, wether it's side on or front on, some of the impact is so great your going to lose a fin whichever system you have,...you just have to weigh up which is the easiest repair...I have been building boards for 39 years and just about seen it all...glassed on can tear out a chunk of foam as big as your fist...boxes hit sideways make a horrible mess and are mothers to remove...from my experience the fcs system is the best as far as an economical repair is concerned,and the choice of fin designs is way ahead of the rest...the solid glass range is the toughest...I think they may even have a new plug design specifically for kie and tow boards too...best thing to do is DON'T HIT ANYTHING!!
hmmm..... think i'll stay with the plastics. Much rather replace the fin than mess with resetting plugs or boxes, and a quick fin swap will let me keep kiting.
my guess is Kelly drives his turns with much more rail than fin... i got heaved to the side and as i lost my rail edge, the sideways force must have shifted to the fin and sheared it off
Futures may have strong enough fins to roll a fin box but it has never happened to me whereas I've had FCS fins snap from the crumbly foam balls pushing by board up on the sand sideways and snapping the fins off. FCS fins are getting bloody expensive and if you snap 6 or 7 fins per season, at $70 per set you are on your way to the cost of half a new board.
You's can keep your FCS, I'll stick to Futures. Like I said, haven't broken one yet, nor have I stressed or cracked boxes out, and yes I have run over reef with them. Messed up the fin, but nothing sandpaper wasn't able to fix. 
Cheers,
KH
yeah kitehard, I do agree, sideways pressure is where the fcs system is most vulnerable, and the system is designed to snap the tabs off before breaking the plug (at least in the plastic series, not so in the solid glass) but if you use the solid glass and reinforce around the plugs, I think the strength of the system is allmost comparable to other box systems and like I said a lot easier to repair...you just drill the broken plug out and insert a new one...definatley the lightest system on the market. but whatever floats your boat...if your on a good thing..stick to it ( but if you find something better...switch.)
I've lost lots of fins kiting but never from water pressure alone (if they come off while kiting they were probably allready fractured from an earlier collision).
Futures are definitely stronger but I've smashed them as well and the repair is a pain as you have to cut the remains of the old box out.
Repairing a FCS plug can normally be done by pulling the damaged plug out cleaning up the hole a bit, pouring in some resin then squishing it back in place, easy!
If encounters with the bottom are likely I prefer to use plastic fins as they have a bit more give in them and do not seem to transfer as much impact to the board when you hit the reef.
I use plastic FCS fins but a plastic fin in a futures box could be the ideal compromise as Im not sure whether they would be strong enough to damage the futures box like a glass fin does.
Ive got a litewave quad surf - have had it for 2 years and no problems - I need new fins cos of all the rock dings to the front fins. the foil is completely screwed but the fins are still there and the fin box still tight - its like a tuttle box on a poleboard - bolt through the deck - solid. Ive been boosting huge, kite looping, riding 5m swells to 2 foot mush, accidentally hitting sand and rock, abusing the board badly. Still going.
I rate it!
One bad thing about Futures is there not as widely carried as FCS so if you don't have a spare with you and can't find a future fin nothing else will go/stay in the box.
The FCS Fusion plug is basicaly a rip off the probox set up, then again companies tend to copy the good ideas.
FCS Crap WT..............Naaaaaaaaaaaaaaa FCS are fine I use them in all my boards, some of which have a single pulg .
All fins bases are going to have issues when ridden into the reef or sand, there is a good chance of ripping some board out with future's too.
The question about fins however.
The M5's are a good all round fin, You can use it to compare to others if you want more drive have a look at a wider base fin.
Generally if the tip is wide it's gonna be a stiffer fin to turn, if the fin has a lot of rake in the tip it'll also make it a stiff fin.
Conversely if the tip is narrow through the rake and flexes this enables the fin to release on a change of direction.
This is why the orange AL Merric AM2 fins are so popular, and I guess the Simon Anderson's, Hahah the list goes on an on..
The M5's are a glass fin which works fine for kiting.
There are also performance models that are again stiffer and lighter.
At the end of the day it all depends on what board your riding how HEAVY you are and what your doing out there.
To loosen up your board you can put a smaller back fin in.
What ever base your using play around with all kinds of fins, that is a good thing about FCS as there are crap loads of available fins to choose from.
There is also FCS demo fins from surf shops.
LOL that's 5 minutes i am never getting back, I hope it helped a little..
and Matt if you don't hit the reef they wont fall out, follow my example ;P
hmmm now i realize the question was for strength not performance, make that six minutes I am not getting back...ihhhh......
I have scraped the bottom a heap of times on my Surftech boards with FCS fins with no worries . prob in the construction..
If you are in Sydney, go to Dion Chemicals Harbord Rd Brookvale. They have FCS equivalent fins for less than half the price of OEMs and as good or better quality.
