Having an issue with my fuselage on my Starboard Race Foil. The Aluminium threads are wearing out from the constant assembly and dismantling. Looking at having to drill out and insert Helicoils but as these are stainless there will be an electrolysis problem.
Has anyone else encountered this problem? Any ideas?

Just brainstorming here. Could you bond in some stainless nuts or or threaded inserts? The epoxy would isolate the two metals. It would take some precise work though.

Or, if practical, bore out and re-thread for larger fasteners. Then be more careful when assembling the thing.

Threading into aluminium... what a great idea!

I had a sportster that's gearbox was basically held in place with helicoils, so there wasn't an issue with strength.
The only thing that you've identified that I can also see a problem with is the electrolosis. But, if you keep a can of crc with you each time you undo the bolts, I think the helicoil answer would be the go after a quick squirt in each hole before replacing the bolts.

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Shifu said..
Just brainstorming here. Could you bond in some stainless nuts or or threaded inserts? The epoxy would isolate the two metals. It would take some precise work though.

Or, if practical, bore out and re-thread for larger fasteners. Then be more careful when assembling the thing.

Threading into aluminium... what a great idea!

So far have looked at SS helicoils that will do the job. means tapping the existing holes which is not a problem it is the corrision that is a concern. It has been suggested to use locktight as an isolating agent. not sure if this is sufficient isolation.
Agree threading into aluminium not the greatest idea. Everything else with the foil is fantastic!!!!!!!!
As for being careful. Hmmm not sure on this one. Threads are not cross threaded as the damage is in the centre. Too much tourque when i am tightening maybe but only using the supplied tool and I am not superman.
Appreciate any feedback for anyone who may have experienced the same problem.

Why not use replaceable brass nuts like in fins , Is there a problem between brass and alloy ?

So why not spin a few turns of plumbers teflon tape on the threads ,to stop corrosion?

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olskool said..
So why not spin a few turns of plumbers teflon tape on the threads ,to stop corrosion?

After looking at the Slingshot maintenance manual (rinse... teflon tape... lanolin), I've decided that carbon only is the way to go.

7-nation.app.box.com/s/teojpnh8peoc1s96c69ls9a6k19bkwoy

(Off-topic, Slingshot was the first to market with carbon-shell harnesses, which are supposedly the best thing since sliced bread. But DO NOT search for "slingshot harness". Their fancy harnesses are under the "ride engine" brand.)

We used to helicoil aluminum yatch winches with ss inserts for the self tailing attachments .
They were loctited & never had problems that i heard of with electrolysis.
I wouldn't see that as a problem then in a windsurfer

AFS foils use stainless inserts and stainless screws, each are a different grade meaning ? no issues with micro welding

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olskool said..
So why not spin a few turns of plumbers teflon tape on the threads ,to stop corrosion?

I would be wary of using threadtape...
if not done correctly it may Increase the chances of cross threading as Ali is soft as.
better bet is to grab an aerosol of lithium grease or similar and give the holes an occasional squirt.

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AUS 814 said..
AFS foils use stainless inserts and stainless screws, each are a different grade meaning ? no issues with micro welding

How come...?

hmm.... making me think might do the non conducting grease thing and leave my main foils and fuselage I tend to use together as one to hold off the issue. I wonder if grease would reduce the wear?

Duralac is the go it's been around for years perfect for s/s and ali it's been used in marine applications for a long time and proven

^+1 Duralac is great for once only assembly. I use it on my boat fixture mounting bolts. No corrosion. But it sucks to undo n rethread coz its gooey n messy. Most foilers ive seen undo everything each sail?

Alu masts need rinsing about once every 3 or so days with everyday use else corrosion starts inside the mast.
Now if u sail less often, consider corrosion your concern.

Which holes are threading? I noticed the short horizontal screws into the mast have inserts that can be replaced.....

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Ezric said..
Which holes are threading? I noticed the short horizontal screws into the mast have inserts that can be replaced.....

It is the holes into the fuselage where the foils are screwed on. They need to be taken apart after every sail especially if changing around foils and fuselage. The aluminium can not cope with the constant screw in and screw out action. Sounds like the helicoil with locktight seems to be the solution. Am surprised other haven't experienced the problem....yet.

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actiomax said..
We used to helicoil aluminum yatch winches with ss inserts for the self tailing attachments .
They were loctited & never had problems that i heard of with electrolysis.
I wouldn't see that as a problem then in a windsurfer

thanks i think this is the solution.

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casio4 said..

Ezric said..
Which holes are threading? I noticed the short horizontal screws into the mast have inserts that can be replaced.....

It is the holes into the fuselage where the foils are screwed on. They need to be taken apart after every sail especially if changing around foils and fuselage. The aluminium can not cope with the constant screw in and screw out action. Sounds like the helicoil with locktight seems to be the solution. Am surprised other haven't experienced the problem....yet.

how many session have you had? I'm on maybe 12 - 14 sessions looked last night still looks fine. I don't crank them tight, just a gentle snug up.

Monel is the best material to use against aluminium to minimise corrosion not sure if you can get monel helicoils but that is the best bet long term otherwise duralac on 316 stainless helicoils for the helicoil installation should work moly grease on the bolts

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scottydog said..

casio4 said..

Ezric said..
Which holes are threading? I noticed the short horizontal screws into the mast have inserts that can be replaced.....

It is the holes into the fuselage where the foils are screwed on. They need to be taken apart after every sail especially if changing around foils and fuselage. The aluminium can not cope with the constant screw in and screw out action. Sounds like the helicoil with locktight seems to be the solution. Am surprised other haven't experienced the problem....yet.

how many session have you had? I'm on maybe 12 - 14 sessions looked last night still looks fine. I don't crank them tight, just a gentle snug up.

Race fuselage probably used maybe 20 times since i got it. Not tightening too tight but reasonably firm. Only using the supplied tool so cant get too much pressure on.

Have you guys not heard of Tefgel?
my Alloy foil is nearly 18mths old and used weekly at least with absolutely zero indicators of corrosion or thread damage.

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RAL INN said..
Have you guys not heard of Tefgel?

Is Tefgel similar to Duralac?
The local yacht riggers use Duralac anywhere S/S meets Alloy mast sections.

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RAL INN said..
Have you guys not heard of Tefgel?
my Alloy foil is nearly 18mths old and used weekly at least with absolutely zero indicators of corrosion or thread damage.

its not a corrosion issue. It is the physical wearing out of the aluminium thread from the SS screw being inserted and removed after every session. The screws are not in long enough for any corrosion to occur. It is the fact the aluminium is soft and has worn out. Hence the need for a long term solution.

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azuli said..

RAL INN said..
Have you guys not heard of Tefgel?

Is Tefgel similar to Duralac?
The local yacht riggers use Duralac anywhere S/S meets Alloy mast sections.

Tefgel is anti seize, and a lubricant and provides corrosion protection by creating a film/barrier between metals.

Duralac contains chromate and converts the aluminium creating a corrosion resistant surface.

en.wikipedia.org/wiki/Chromate_conversion_coating

I have used a similar chromate paste when using stainless rivets with 6061 sheet and like others said Duralac is likely best for permanent assembly and Tefgel for the screws .

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casio4 said..

RAL INN said..
Have you guys not heard of Tefgel?
my Alloy foil is nearly 18mths old and used weekly at least with absolutely zero indicators of corrosion or thread damage.

its not a corrosion issue. It is the physical wearing out of the aluminium thread from the SS screw being inserted and removed after every session. The screws are not in long enough for any corrosion to occur. It is the fact the aluminium is soft and has worn out. Hence the need for a long term solution.

If not a corrosion issue then still a abrasive issue so still best answer is tefgel.
also use longer bolts to get more surface area

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fjdoug said..

I have used a similar chromate paste when using stainless rivets with 6061 sheet and like others said Duralac is likely best for permanent assembly and Tefgel for the screws .

Thanks for the helpful info fjdoug.

Initial maintainance videos on the web stressed lubing the threads..all.. to keep the interface intact and to allow for removal and installation.
Another vid mentioned threadloc to keep the bolts tight.

Search for a product called KeenSert, or keysert, I believe you can get them in brass/bronze which would be ideal to stop both The electrolysis and wear issues.