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304 is veritable rubber when you watch it on a tensile test machine. I would prefer 316.
One out of one clinical tests show that:
Foil with 84 cm wing and 71 cm mast does not float
Fuselage with 84 cm wing and 48 cm stabiliser will float
Fuselage with 84cm wing and 42 cm stabiliser will also float
Fuselage with 76 cm wing and 42 cm stabiliser will sink
so if the bolts snap, make sure you are using the 84 cm wing
I've found if you coat the bolts with a generous amount of TefGel, in addition to providing corrosion protection, it helps keep the bolts tight.
I disassemble the foil and reapply the TefGel about once a month.
when a foyle can swim it's great. But when the foil drowns you cannot prove that it was done badly. How did the FRPGEAR badly embedded on the foyle and at the first ride the wing was torn off and the wing sank.
Had a bolt fail on Slingshot fuselage today. Tried the 35.4" mast for first time, (still learning). The mast bolts were tightened only a few hours before the failure. On Infinity 84 wing, maybe a few small breaches, front bolt sheared.
Windsurfed back using the mast as a fin, with tail wing hooked under the back foot straps, and main wing sitting on the water.
Appreciate all the metallurgical discussion in this post, will try to get some 316SS bolts.
The other half of the sheared bolt is still in the thread. Thanks for the advice on how to remove, will get a left hand drill bit to get out.
North beach Windsurfing immediately sent a new mast and titanium bolts under warranty.
Got some 316SS bolts from McMaster-Carr, am using those.
It worked! That is a block of high density EVA (swimming kick board) about 3cm x 20cm x 9cm. My idea is that I cut a hole out of it so it sleeves over the mast, shape to be aerodynamic and glue on with contact adhesive. I'll probably lose half that foam volume through that process, so remains to be seen if it will still float by then.
thinking further, a block of polystyrene shaped to fit, then laminated with fibreglass would be a nicer solution.
Stretchy, why not just a simple tether from the board to the mast in case of striking an object or box failure. This failure mode, afaik, is relevant only to Slingshot because unlike anyone else that I know, they don't use a socketed joint between the fuse and mast so the bolts take on a much larger structural role than other designs. The Cruiser (from what I can tell from photos) uses both bottom and side bolts like the Starboard freeride/race fuses do, that's much stronger than the SS design.
Does anyone else know if there are other brands susceptible to this mode of failure?
Does salt water have anything to do with the hardware failing more than in fresh water?
Yes, salt water eases electrical currents that cause corrosion by thousands of times. There are ways to measure electrical conductivity. It does not take much electrolyte (salt) to increase the conductivity by orders of magnitude.
If you simply use stainless steel for screws and bolts, you can use aluminum and/or carbon without getting much corrosion. 316 stainless is fine for this. Some other stainlesses, too, but avoid 304 since it is like rubber.
The broken bolt shaft came out easily with a few taps of a sharp countersink punch to make it turn anti clockwise, then turn with fingers.
The "ezi out" left hand drill hardly scratched the surface of the titanium.
I'm the proud owner of a new 99 wing for my Slingshot Wizard 125. I'll be using it with the 90 mast as soon as we get a little wind in Ohio. I've been using the 76 wing so far.
I'm a bit paranoid about losing my new expensive wing to a bolt failure. I snapped the bolts at the fuse-mast joint earlier this year when I grounded my foil in waist-deep water. Fortunately a swimmer found the fuse and wings on the bottom undamaged except for the sheared bolts. I'm thinking about running some strong fishing line from a rear foot strap down the mast and attaching to an unused hole in the fuse--just for insurance. I don't think the line would add too much drag.
What do you think?
Just switch the bolts to a good grade of aluminum then if you hit something they just might bend instead of snap.
