Anyone with experience regarding titanium screws versus stainless steel screw for foils?

I think a lot of the Slingshot stuff comes with Titanium bolts. I'm sure that crew can elaborate their experiences.

Have you bought some Slingshot foils now???

Select to expand quote

DarrylG said..
I think a lot of the Slingshot stuff comes with Titanium bolts. I'm sure that crew can elaborate their experiences.

Have you bought some Slingshot foils now???

Plenty of people FTY, time to give foiling away and take up full time comedy?

It would be interesting to have the standard bolts from slingshot tested to see what they are actually made from. I have had the standard slingshot bolts fail. if you search you will see posts on this point and discussions regarding stainless versus slingshot's offerings. I personally swapped out my slingshot bolts with titanium motor racing bolts from the UK and have had no issues with them. as to the galvanic reaction between the stainless helicoils in your race foils and the titanium, my uninformed understanding is stainless and titanium are close together on the potential scale so less likely to react.

Titanium also limits your toolkit should a bolt get stuck. I purchased some used SlingShot gear that got delivered all bolted together. Prior owner had rounded out the hex heads on a few fasteners. Tried welding a steel nut onto the stripped bolts. Steel on Ti creates a weak and porous weld that shatters when you apply torque. In the end, I machined out the heads and took the mast and plate apart. I still could not get the titanium to break free so I ground down the nubs and welded the plate and mast together with aluminum and called it fixed. Not everyone has access to machine shop tools. Very few have access to weld titanium nuts onto titanium bolts. And that is how I discovered that SlingShot use titanium hardware...

Good quality Stainless bolts will bend to a point where Titanium will snap. Lots of lost slingshots out there confirm this.

The Taaroa foils come with titanium bolts. So far so good - very few turns into the stainless helicoils yields a very solid and stiff connection. I'm using SS for board-mast as the supplied titanium bolts were too short but everything else is titanium.

Currently using 316 (a-4) stainless steel bolts for the fuse to mast connection. Apparently that is a stronger type of stainless...

Select to expand quote

windfred said..
Good quality Stainless bolts will bend to a point where Titanium will snap. Lots of lost slingshots out there confirm this.

I have switched the mast-fuse bolts to 316 stainless. I have seen several examples of stainless bolts bending. A problem I had with the screws working themselves loose during a session turned out to be due to a bolt with a very slight bent. The more impressive example was when the rear tuttle bolt in my GT-R plus came loose mid-flight due to "user error". The front bolt (M6x80 stainless) held on, but ended up with a very pronounced S-bend.

The two M6 screws holding the Starboard foil in the tuttle box appear rather flimsy, compared to the other connections which are so much more solid than the Slingshot connections. After seeing one of the PWA sailors crash at the recent races because of one of his tuttle screws broke, I'm seriously considering getting the track adapter.

Select to expand quote

thedoor said..
Currently using 316 (a-4) stainless steel bolts for the fuse to mast connection. Apparently that is a stronger type of stainless...

A4 or A2 is more about the corrosion resistance, not strength. Realistically, for our use case the difference in corrosion resistance isn't massive, assuming you take reasonable care of your gear. A4 is still obviously preferred, but I have found A4-70 fasteners a bit hard to get a hold of here, so I have some A2-70 fasteners as well.

A4 = 316SS
A2 = 304SS

What you should be looking for the next 2 digits identifying the fastener, i.e. A4-40, A4-70, or A4-80. The bigger the second number the better, I'd suggest that -70 is the minimum that anyone should use on foil gear. If your stainless fasteners are unmarked, then I'd assume they are cheese grade, aka I wouldn't risk it unless you are very confident that they have been supplied and approved by the foil manufacturer (and even then I don't think many of them are particularly well educated, e.g. slingshots snapped titanium fasteners).

Handy reference chart.
www.anzor.com.au/technical/strength-and-mechanical-properties/stainless-fastener-tensile-comparison-chart

Unfortunately, a non insignificant portion of the windsurfing industry and seemingly a lot of the foil manufacturers aren't very well versed with some of the basics around specifications of fasteners or fastener QA.


Its also worth noting that an M8 fastener can handle 80% more load than an M6 fastener of the same grade. If the equipment geometry allows, and it appears most could easily accommodate M8 fasteners, then I don't see any reason why manufacturers would want to use anything less than an M8 in any critical connections. M10 is obviously too large for most areas, and especially CSK fasteners, but M8 is easy to accommodate within the geometry of the products, and really I think should be adopted as a minimum standard for front wings and mast-fuselage connections.

Proper Titanium Bolts, i.e. Grade 5 on paper appear as if they should be at least as strong as A4-70 stainless fasteners, but pricing is fairly steel (maybe $80-100 for set of fasteners for foil?), so not sure what is to be gained. They do also appear to have higher fracture toughness as well. Anecdotally people do seem to think they are brittle, but again this could related to poorly specified materials, rather than any inherent issues with titanium fasteners.

www.ti-shop.com/nuts-bolts/titanium-countersunk-bolts/ti-csb-250-titanium-gr5-m6-50mm-cou-sunk-head-bolt-1.0mm-pitch.html
www.ebay.com.au/itm/113959150768

Belmetric.com has a good selection of A4 stainless screws with fully threaded shafts on even the 100 mm long screws.

Slingshot bolts are magnesium......duh

Select to expand quote

boardsurfr said..

The two M6 screws holding the Starboard foil in the tuttle box appear rather flimsy, compared to the other connections which are so much more solid than the Slingshot connections. After seeing one of the PWA sailors crash at the recent races because of one of his tuttle screws broke, I'm seriously considering getting the track adapter.

Given the number of foilers on here and the foilers they know, the number of snapped tuttle head bolts reported is remarkably low. It's a lot easier to invest in fresh bolts once a year rather than ditching one system for another.

Select to expand quote

swoosh said..

thedoor said..
Currently using 316 (a-4) stainless steel bolts for the fuse to mast connection. Apparently that is a stronger type of stainless...

A4 or A2 is more about the corrosion resistance, not strength. Realistically, for our use case the difference in corrosion resistance isn't massive, assuming you take reasonable care of your gear. A4 is still obviously preferred, but I have found A4-70 fasteners a bit hard to get a hold of here, so I have some A2-70 fasteners as well.

A4 = 316SS
A2 = 304SS

What you should be looking for the next 2 digits identifying the fastener, i.e. A4-40, A4-70, or A4-80. The bigger the second number the better, I'd suggest that -70 is the minimum that anyone should use on foil gear. If your stainless fasteners are unmarked, then I'd assume they are cheese grade, aka I wouldn't risk it unless you are very confident that they have been supplied and approved by the foil manufacturer (and even then I don't think many of them are particularly well educated, e.g. slingshots snapped titanium fasteners).

Handy reference chart.
www.anzor.com.au/technical/strength-and-mechanical-properties/stainless-fastener-tensile-comparison-chart

Unfortunately, a non insignificant portion of the windsurfing industry and seemingly a lot of the foil manufacturers aren't very well versed with some of the basics around specifications of fasteners or fastener QA.


Its also worth noting that an M8 fastener can handle 80% more load than an M6 fastener of the same grade. If the equipment geometry allows, and it appears most could easily accommodate M8 fasteners, then I don't see any reason why manufacturers would want to use anything less than an M8 in any critical connections. M10 is obviously too large for most areas, and especially CSK fasteners, but M8 is easy to accommodate within the geometry of the products, and really I think should be adopted as a minimum standard for front wings and mast-fuselage connections.

Proper Titanium Bolts, i.e. Grade 5 on paper appear as if they should be at least as strong as A4-70 stainless fasteners, but pricing is fairly steel (maybe $80-100 for set of fasteners for foil?), so not sure what is to be gained. They do also appear to have higher fracture toughness as well. Anecdotally people do seem to think they are brittle, but again this could related to poorly specified materials, rather than any inherent issues with titanium fasteners.

www.ti-shop.com/nuts-bolts/titanium-countersunk-bolts/ti-csb-250-titanium-gr5-m6-50mm-cou-sunk-head-bolt-1.0mm-pitch.html
www.ebay.com.au/itm/113959150768

OK good to know. I don't see the second number, maybe they use something different in the US

www.boltdepot.com/Product-Details.aspx?product=22292

The McMaster stuff tends to have second number. Often times you can call the supplier to verify. If it's not stated, then buyer beware.

Select to expand quote

swoosh said..
The McMaster stuff tends to have second number. Often times you can call the supplier to verify. If it's not stated, then buyer beware.

They also mark 316 with a dot (it looks like a bur) if theres not enough room to put writing on the bolt. Oddly enough, the bolts on my f4 set aren't marked in any way. I can only presume they're 304.

agree about the tuttle head bolts. It'd be easy for them to put m8 bolts there. It'd be a lot more re assuring given the m6 bolts have failed before.