Sorry meant to say stainless my mistake

I'm pritty sure the i99 floats with the fuse attached(the i84 floats).

Thanks for that topic. I did not realize the bolts where out of Titan - that is brittle as hell. I just checked and yes, mine Titan too.

Light and nice material, expensive too - but apparently in this case too brittle.... which surprises me actually.......

Probably these cases where the bolts snap where over-tightening or too loose ....?! Or maybe a bad batch ... or all together!?

But hey guys, no bad feelings towards Slingshot - they just wanted to keep the set light and Titanium should have done the trick .... That material is used in much more demanding applications.

However, just ordered 316 SS - better save than sorry. So thanks again for the topic.

@Slingshot: Maybe you guys can comment on this. What is your opinion?

Carv, it's possible that loose bolts contributed to their failure. I've noticed that after a long session those fuse/mast bolts can loosen up. This is even with care, ie occasional lanolin oil to reduce chances of seizure. It seems like a catch-22: don't keep them lubed and the seize; lube them occasionally and maybe they're too slippery. One theory proposed on this forum is that if you don't lube them they can loosen over time. What a quandary. Let us know how you get on with 316 SS.

What's so important at 3:36 and 11:01 of this Aug 11 2020 SS video.

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marc5 said..
Carv, it's possible that loose bolts contributed to their failure. I've noticed that after a long session those fuse/mast bolts can loosen up. This is even with care, ie occasional lanolin oil to reduce chances of seizure. It seems like a catch-22: don't keep them lubed and the seize; lube them occasionally and maybe they're too slippery. One theory proposed on this forum is that if you don't lube them they can loosen over time. What a quandary. Let us know how you get on with 316 SS.

Use TefGel. They won't come loose by themselves.

As for the supplied bolts, I am almost certain they have been taken for a ride by their hardware supplier. I don't think those bolds are made from titanium. I've had to drill one out yesterday because I had stripped the head. The drill went in like it was butter. This was with a stock standard drill bit and a battery powered hand drill.

But as others have said this is an inexpensive fix. Most fastener supply shops will have quality marine grade stainless steel and titanium bolts for next to nothing. Just buy a bag full for $20 and regularly replace them.

I think bolts seem to be the Achilles heel of all windsurf equipment. The vast majority of windsurf brands seem to have problems with excessive rust on bolts. Be it boom heads, extension inserts, sail cleats.

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CYVRWoody said..
What's so important at 3:36 and 11:01 of this Aug 11 2020 SS video.

16. 05 "Screw em down - again this is gunna take forever". Surely you don't do this disassembly after every session?

" Crank the m8s but don't crank the m6s crazy hard."

Would a torque wrench solve a lot of the loose bolt and lost foil problems?

I've been using a fat-handled screw driver and bits are often a little loose when I come ashore. I've now found a grander spanner but will have to be careful of over-tightening. No luck googling torque of stainless M8 bolts into aluminium. Anyone have a number?

As my mechanics engineering professor at Uni used say: "when you don't have figures at hand follow the 'after very tight comes very loose very quickly' rule"

All very good but we still don't have figures. Torque wrenches are cheap.
www.amazon.com.au/TEKTON-24330-8-Inch-ft-lb-13-6-108-5/dp/B00FMPKAD0/ref=asc_df_B00FMPKAD0/?tag=googleshopdsk-22&linkCode=df0&hvadid=341743966998&hvpos=&hvnetw=g&hvrand=1711955325408005122&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9070534&hvtargid=pla-382659618649&psc=1


Or maybe 6Nm is enough.
www.amazon.com.au/Pro-Bike-Tool-Adjustable-Torque/dp/B07D6QD9T6/ref=asc_df_B07D6QD9T6/?tag=googleshopdsk-22&linkCode=df0&hvadid=341774266315&hvpos=&hvnetw=g&hvrand=1711955325408005122&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9070534&hvtargid=pla-487068585726&psc=1

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stehsegler said..

marc5 said..
Carv, it's possible that loose bolts contributed to their failure. I've noticed that after a long session those fuse/mast bolts can loosen up. This is even with care, ie occasional lanolin oil to reduce chances of seizure. It seems like a catch-22: don't keep them lubed and the seize; lube them occasionally and maybe they're too slippery. One theory proposed on this forum is that if you don't lube them they can loosen over time. What a quandary. Let us know how you get on with 316 SS.

Use TefGel. They won't come loose by themselves.

As for the supplied bolts, I am almost certain they have been taken for a ride by their hardware supplier. I don't think those bolds are made from titanium. I've had to drill one out yesterday because I had stripped the head. The drill went in like it was butter. This was with a stock standard drill bit and a battery powered hand drill.

But as others have said this is an inexpensive fix. Most fastener supply shops will have quality marine grade stainless steel and titanium bolts for next to nothing. Just buy a bag full for $20 and regularly replace them.

I think bolts seem to be the Achilles heel of all windsurf equipment. The vast majority of windsurf brands seem to have problems with excessive rust on bolts. Be it boom heads, extension inserts, sail cleats.

Re. "Most fastener supply shops will have quality marine grade stainless steel and titanium bolts..." - can you recommend one in Perth pls?

From the Fuller Fasteners website, for A2-70 and A4-70 fittings:


The figure given for M6 is 7.3 NM. Make-up torque range for the disk brake caliper mounting bolts (M6) on my bicycles is 6 - 9 NM. These bolts come in either stainless steel or titanium and the frame material they screw into can be steel, carbon, aluminium or titanium. So 7 NM seems a valid figure for the M6 bolts on the Slingshot foil assembly.

The torque given for an M8 bolt (mast to fuse / wing) is 17.7 NM. That seems a lot, but in any case it is more than 6 NM...

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Plainview said..
Re. "Most fastener supply shops will have quality marine grade stainless steel and titanium bolts..." - can you recommend one in Perth pls?

WA Bolts in Bibra Lake. A boating supply shop in Freo send me to there. From memory the titanium bolts were $1.5 each.

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stehsegler said..
Use TefGel. They won't come loose by themselves.

Incorrect. I have found the screw closer to the front wing to be loose quite often after a session. That happened both without any lubricant, but also when using TefGel. The problem is worst with one of the 4 masts we use most often, where it seems to happen every time. But is has happened on the other masts, too. It happens more regularly to me than to my wife, which may be weight related (> 90 vs. < 60 kg).

The only thing that seems to work most of the time is to not use the "bad" mast, and to crank the screws as tightly as possible. I'm using 316 steel for both screws and Allen wrenches. The wrenches are a bit longer than the ones that Slingshot sends, have a better head, and don't start rusting after the first session. A bit hard to understand why SS can't include a decent set of wrenches with a $1300 foil.

I'm surprised by that. Every time I use the Tefgel it goes black and gooe almost instantly and bolts are definitely more sticky then without. Re not including a proper wrench set I guess it comes down to cost. If you look at what half decent sets cost at Bunnings I'm not surprised and Bunnings would be buying at scale.

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boardsurfr said..

stehsegler said..
Use TefGel. They won't come loose by themselves.

Incorrect. I have found the screw closer to the front wing to be loose quite often after a session. That happened both without any lubricant, but also when using TefGel. The problem is worst with one of the 4 masts we use most often, where it seems to happen every time. But is has happened on the other masts, too. It happens more regularly to me than to my wife, which may be weight related (> 90 vs. < 60 kg).

The only thing that seems to work most of the time is to not use the "bad" mast, and to crank the screws as tightly as possible. I'm using 316 steel for both screws and Allen wrenches. The wrenches are a bit longer than the ones that Slingshot sends, have a better head, and don't start rusting after the first session. A bit hard to understand why SS can't include a decent set of wrenches with a $1300 foil.

Check if the bottom of the mast is perfectly straight with a straight edge or something like that. Maybe the bottom of the mast and the fuse don't mate perfectly, that is, there is a Minuscule gap either At the front of the mast or the back. If there is a gap, I don't think you can close that gap with the Allen wrench and that might be the reason for loose bolts.

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stehsegler said..

marc5 said..
Carv, it's possible that loose bolts contributed to their failure. I've noticed that after a long session those fuse/mast bolts can loosen up. This is even with care, ie occasional lanolin oil to reduce chances of seizure. It seems like a catch-22: don't keep them lubed and the seize; lube them occasionally and maybe they're too slippery. One theory proposed on this forum is that if you don't lube them they can loosen over time. What a quandary. Let us know how you get on with 316 SS.

Use TefGel. They won't come loose by themselves.

As for the supplied bolts, I am almost certain they have been taken for a ride by their hardware supplier. I don't think those bolds are made from titanium. I've had to drill one out yesterday because I had stripped the head. The drill went in like it was butter. This was with a stock standard drill bit and a battery powered hand drill.

But as others have said this is an inexpensive fix. Most fastener supply shops will have quality marine grade stainless steel and titanium bolts for next to nothing. Just buy a bag full for $20 and regularly replace them.

I think bolts seem to be the Achilles heel of all windsurf equipment. The vast majority of windsurf brands seem to have problems with excessive rust on bolts. Be it boom heads, extension inserts, sail cleats.

I reckon there is a few factors with fasteners quality, number 1 being that most of these manufacturers have no idea about QA or properly vetting their suppliers, blaming suppliers for taking them for a ride is a cop out, particularly if they haven't done the upfront engineering, specifying or QA as part of their manufacturing.

It's very rare to find fasteners supplied with gear that actually has manufacturers markings on it. The two I can recall recently, are Chinook when I pulled apart my mast base to replace the tendon, and the fasteners on my Fanatic Flow1000 Foil.

Other things to note is that really even 316 doesn't perform perfectly in a salt water environment. And also they always tend to rust where the contact other metals which may contaminate them. I've noticed that Philips head fasteners always corrode in the +, now I wonder if that's because water sits in there or due to ferrous contamination from use of non-stainless drivers.

Luckily for us, in Australia if you go to any of the good local industrial suppliers (don't go to Bunnings), you will find good quality fasteners for very cheap. In Brisbane, I'd use Bolt King, Bolts and Industrial or Anzor. Otherwise United Fasteners is I'm pretty sure Australia wide, generally these guys are used to working with tier 1 contractors, who will require traceability and material certificates for everything supplied so you will get good quality fasteners.

What slingshot charge for their fastener kits is pure profiteering, especially if the quality of the fasteners is in doubt. This is literally $25 of fasteners at worst, and they have it marked up to $179...

slingshotaustralia.com.au/collections/foil-spares/products/2019-slingshot-hg-foil-hardware-kit-fkite-fsurf-fsup-fwind

What is the thread pitch of the bolts used in Slingshot foils? Sounds like finding SS 316 bolts is a good idea.Best supplier in the States?

8mm x1.25 x 50 mm might be wrong on the length McMaster Carr is the company 316 stainless come in a 5 pack. Also your local hardware store will have A2 more than likely that will work not as strong as A4 but I have used them in a pinch no problems.

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marc5 said..
What is the thread pitch of the bolts used in Slingshot foils? Sounds like finding SS 316 bolts is a good idea.Best supplier in the States?

I don't know If they are the best but you can try boltdepot and mcmastercarr online or fastenal as a brick and mortar option. If you go to an actual store be sure they have the bolts in stock before driving (especially the m10s because sometimes they have to be ordered due to the length).

I was curious when I got into Foiling about torque specs and how tight is tight enough. I just crank em down with the Allen wrench until I can't turn them except for the wings. The wings I don't give quite as much crankin power because of stripping the threads. But I have those bolts tight enough that they will not come loose. Haven't broken any hardware or stripped anything. It seems like common sense, make it tight. I don't understand why so many bolts are coming loose? I do believe in changing out the bolts once a season.

Wyatt's video convinced me to try Teflon tape at least on the mast/fuse bolts, which tend to come loose on me during a long session, even when cranked. He says it's the vibration that loosens them--several wraps of tape prevent it. I like using tape for plumbing joints unless I'm going to be taking the pipes apart occasionally, because the tape gets ripped up and messy on the threads after an in/out. Not sure how mast inserts will handle frequent disassembly with a lot of tape on the bolts.

In general, I've not been impressed with the quality that the slingshot foil systems have. All the people I know that have them, have some sort of issue.

Low strength thread locking compound is probably a better bet then teflon tape, tho I'm sure teflon tape helps a tiny bit. I'd just stick to Tefgel tho.

Minor vibrations shouldn't make a big difference to a properly engineered, and torqued connection. If you can, borrow a good quality torque wrench, set it to the correct torque, and then tighten the fastener holding the torque wrench a similar distance from the head as you would with an allen key wrench. That way you can get a "feel" for what the correct tightness is.

Also torque settings can vary greatly depending on thread lubricant, thread condition etc, so I generally err on the side of caution and slightly undertighten, rather than overtighten. The fasteners generally are so oversized for the application that it shouldn't matter. If you are worried you have overtightened them, which can be easy to do with smaller fasteners, just replace them, they are cheap.

Another way to look approach it is:
- 6Nm is the equivalent of applying 5kg to a 120mm long lever arm (say if you allen key wrench is 120mm long)
- 16Nm is the equivalent of applying almost 11kg to a 150mm long lever arm.

This way you can get a bit of a "feel" for how tight the fasteners should be, which should be all that's needed for a foil. You can maybe use some fish scales or luggage scales to do this more accurately

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marc5 said..
What is the thread pitch of the bolts used in Slingshot foils? Sounds like finding SS 316 bolts is a good idea.Best supplier in the States?

1.25 mm pitch, McMaster.com 316ss Flat head hex countersunk, 8mm by 50 mm, pack of 5.

Their website is a bit clunky, so not able to send you a direct link, but it works.

Why do SlingShot go to the length of supplying their foils with the more expensive titanium bolts, if in practice cheaper standard stainless steel bolts appear to be preferred/perform better for the specific purpose?

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oscardog said..

1.25 mm pitch, McMaster.com 316ss Flat head hex countersunk, 8mm by 50 mm, pack of 5.
Their website is a bit clunky, so not able to send you a direct link, but it works.

These: www.mcmaster.com/93395A425/

Just don't buy these 75mm M8s for the tuttle-to-mast bolts. www.mcmaster.com/92290A459/
They are only partially threaded (28mm long) and the threads aren't long enough.

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Cyber said..
Why do SlingShot go to the length of supplying their foils with the more expensive titanium bolts, if in practice cheaper standard stainless steel bolts appear to be preferred/perform better for the specific purpose?

Its not clear to me that the stainless bolts are better. Pretty certain people have sheared stainless bolts too.

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lwalker said..

oscardog said..



1.25 mm pitch, McMaster.com 316ss Flat head hex countersunk, 8mm by 50 mm, pack of 5.
Their website is a bit clunky, so not able to send you a direct link, but it works.

These: www.mcmaster.com/93395A425/

Yep www.mcmaster.com/93395A425/

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lwalker said..

Just don't buy these 75mm M8s for the tuttle-to-mast bolts. www.mcmaster.com/92290A459/
They are only partially threaded (28mm long) and the threads aren't long enough.

Try this for tuttle to mast bolts www.mcmaster.com/93395A535/
Those are supposed to be fully threaded however 80mm long instead of 75mm originals. Maybe someone else knows if threads in mast finish at equivalence of 75mm screw thread, or keep going. Warning: I have not tried them as yet.

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oscardog said..

lwalker said..

Just don't buy these 75mm M8s for the tuttle-to-mast bolts. www.mcmaster.com/92290A459/
They are only partially threaded (28mm long) and the threads aren't long enough.

Try this for tuttle to mast bolts www.mcmaster.com/93395A535/
Those are supposed to be fully threaded however 80mm long instead of 75mm originals. Maybe someone else knows if threads in mast finish at equivalence of 75mm screw thread, or keep going. Warning: I have not tried them as yet.

Those are 90 Degree Countersink heads - won't work. I haven't yet been able to find M8 75mm socket head bolts in SS-316 with long enough threads. I suppose I could put some washers in there - 28mm of thread should be enough - but I think I'd have make them.

Eh... I guess the tuttle-mast bolts are much less vulnerable than the mast-fuse bolts given the geometry of the connection.