When to switch out hardware?

Hi fellow foilers! My second windfoiling season is just over 2 months away. I have SS foiling gear and sail in fresh water. Should I switch out my hardware, or is it still safe to use for another year?

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CoreAS said..

MagicRide said..
Hi fellow foilers! My second windfoiling season is just over 2 months away. I have SS foiling gear and sail in fresh water. Should I switch out my hardware, or is it still safe to use for another year?

We change all hardware on every time change (so twice a year), we foil around 140+ days a year.

So foil about 40 days/ year. Am I still good for another year on same hardware?

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CoreAS said..

MagicRide said..

CoreAS said..

MagicRide said..
Hi fellow foilers! My second windfoiling season is just over 2 months away. I have SS foiling gear and sail in fresh water. Should I switch out my hardware, or is it still safe to use for another year?

We change all hardware on every time change (so twice a year), we foil around 140+ days a year.

So foil about 40 days/ year. Am I still good for another year on same hardware?

I would swap all bolts out ASAP.

Even at 40 days a year I would change all hardware once a year. Not worth the swimming hassle if something goes wrong, also potential loss of wings etc.

It amazes me how fast these bolts can wear out. Inspecting them, they all look in great shape. Are the new bolts still Allen wrench heads?

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CoreAS said..

MagicRide said..

CoreAS said..

MagicRide said..
Hi fellow foilers! My second windfoiling season is just over 2 months away. I have SS foiling gear and sail in fresh water. Should I switch out my hardware, or is it still safe to use for another year?

We change all hardware on every time change (so twice a year), we foil around 140+ days a year.

So foil about 40 days/ year. Am I still good for another year on same hardware?

I would swap all bolts out ASAP.

Even at 40 days a year I would change all hardware once a year. Not worth the swimming hassle if something goes wrong, also potential loss of wings etc.

Well this is an eye opener.

How do stainless bolts fatigue internally ?

I have just recently learned that you want to make sure your fasteners are the right grade of Stainless. Look for a tensile strength of at least 100,000 psi or greater. See my recent post called Mosses issues. Thanks swoosh for doing the math!

I think that if a bolt fails 'internally' it will be a manufacturing defect, majority of other failures such as too little preload, excessive preload, not
fit for purpose are not internal failure cases, and vast majority of stainless bolts that we use are cold formed so no failure from thread forming/ cutting.

people get ultimate limit state loads confused with serviceability or working load limits, big difference and the loads generated from a foil in my opinion at ren well under what we should be concerned about,

as long as we are using A4 316 bolts, rinsed with fresh water after use I think all good,
threaded tapped holes in alloy fuses should be cleared also and rinsed!

its not much coin to change out your fixings periodically, but they are stronger than most people realise
if you want I will do a destructive tensile load test with load cell to confirm on al old ss fixing

Stainless steel wire will also fail from fatigue and that also starts internally and so not visible. If you bend something back and forth the greatest stress on it is going to be where the metal is least able to flex, and that is in the center. The outside can flex the most since nothing constrains it, so if you could see cracks on the outside it would be just when the metal failed.

Well guys, I will then buy new hardware! Once a season should be fine right on 40-50 sessions per season in fresh water?

Something does not seem quite right in this discussion. Automotive bolts will last for years in heat, cold, wet, salt, dirt, etc. Nobody does regular auto bolt replacement. Why would properly specced foil boil bolts wear out? It cannot be from the salt water. Cars in Canada are full of salt for months in the winter. Is the stress on foil bolts stronger than on auto bolts? Or are the bolts not specced properly by the foil companies?

Replacing bolts every 40 sessions may actually increase your risk of failure rather than decreasing it. One of the primary reasons that bolts fail are small manufacturing defects, which are usually internal and invisible. I remember reading one study about bolt failures where about 1 bolt in 100 broke when stress testing, and the cause was generally and internal defect. Replace bolts too often, and you increase your chance that you get a bad one. It's even worse when the quality control for a batch fails, and you get bolts from a bad batch. I remember a few years back when a windsurf rental place got a bunch of new universals, and half of them broke within a week or so. I've had similar experiences with random hardware for non-windsurfing projects.

The other thing to look at is which bolts are subject to high stress. For example in a Slingshot setup, the bolts connecting mast to fuselage carry much higher loads than other bolts. They are also more like to suffer unusual stress since they can work themselves loose during a session. Replacing those would make much more sense than replacing the bolts that hold the front wing in place.

All that assumes the critical bolts are A4 (316) steel. For foiling, especially in salt water, it seems 304 is more likely to break due to corrosion (like the crevice corrosion Shlogger mentioned), and titanium bolts can be brittle (although that might be mostly a quality / QC issue).

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boardsurfr said..
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The other thing to look at is which bolts are subject to high stress. For example in a Slingshot setup, the bolts connecting mast to fuselage carry much higher loads than other bolts. They are also more like to suffer unusual stress since they can work themselves loose during a session. Replacing those would make much more sense than replacing the bolts that hold the front wing in place.

All that assumes the critical bolts are A4 (316) steel. For foiling, especially in salt water, it seems 304 is more likely to break due to corrosion (like the crevice corrosion Shlogger mentioned), and titanium bolts can be brittle (although that might be mostly a quality / QC issue).

Agree with boardsurfr. For slingshot, the mast to fuselage bolts are most likely to fail as have the most tension and torque in the bolts. The foil wing bolts are just holding in position, and the tuttle to board bolts are mostly tension only, unless you are jumping.

Suggest regular replacement of mast to fuselage bolts.

By the way, Houstonkiteboarding had some foil wing bolts for Slingshot with an extra thread of length, much less likely to strip the thread in the cap.

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Trentski said..
"Replacing bolts every 40 sessions may actually increase your risk of failure rather than decreasing it. One of the primary reasons that bolts fail are small manufacturing defects"

sorry but I call bull****, if that were the case structures would be falling down all around us!

I regularly request test Certs for bolts and this is not a hit or miss process!

and galvanic corrosion between carbon and Aluminium, do you mean carbon steel and Aluminium?

sorry but bolts don't just fail under the loads we impose during foiling

if you are worried ( and I'm not) change your 'high stress' bolts and get some sleep!

some poor bastards will be worries every time they go foiling now!

I agree with your first comment, and i do see a lot in this thread thats just undue worry. But its not such a bad idea to change out bolts regularly. I wouldn't worry much about "Micro corrosion/defects" but i would (and do) worry a lot about metal fatigue. Things like using the thread to tow the foil head into the board won't be good for threads or bolts in general. (im not sure why some manufacturers still haven't moved up a bolt size or two, given the m6 bolts have been proven to snap under the load With pitching)


carbon does corrode aluminium, at rate where you shouldn't leave them in contact with each other for extended periods. I forget exactly where in the nobility scale it is, but pretty sure its further away from aluminium than carbon steel is.

and depending in part on how they've designed the foil assembly points, there can be a massive amount of leverage on the wing bolts and fuse to mast bolts as the rider manipulates the board to windward/leeward, the evidence of which can be observed in some of the other threads on here.

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MagicRide said..
So I was talking to my shop about the hardware situation and about ss hardware failing. They told me, I don't need to relplace it every season. They said, it should last a long time. I talked to a buddy of mine about the issue as well. He kite boards on foil and told me the hardware should last for years. Another friend has never changed out his hardware either. They all said, the hardware does not wear from the inside out. So am I missing something, or not understating why I need to replace hardware?

For me it's about looking at the stress said hardware is under. Foil head bolts are always under stress from pitch movement, and in my opinion they are way too small for what they do, so i change them out regularly. On the other hand the mast to fuse joint on my foil is well constructed to spread the load, the connectors not made of too dis-similar metals, and there's 4 bolts, so they more than likely will last for years, i just check them once in a while.

i think a lot of people get trapped in the same old thinking of this hardware is the same as normal gear, not really looking at the differing amount of stress on different kit. Reality is there is a lot more stress on everything with a foil.

The titanium mast to fuselage bolts fail, mine did in freshwater sailing, other's did. Suggest replace with Stainless.

www.seabreeze.com.au/forums/Windsurfing/Foiling/Slingshot-titanium-bolt-failure?page=1

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CoreAS said..
Sounds like you should have just listen to your buds then, really no point in this thread?

No, I value this thread, all your opinions as well as my own sailing buds. In order for me to formulate my own opinion, I need to ask around and get lots of reasons on the topic.