Corrosion is really hitting my fuselage hard. Small pricks in the anodizing have of course grown to considerable size. I've tried coating with tef-gel and boeshield t-9 but they've done little to impede the corrosion. I think my best path forward might be to remove all the anodizing, so at least the corrosion is spread out everywhere along the fuselage.

I've read a bit about using some chemicals for removing the anodizing. It looks like I can use NaOH but it might (will?) etch the surface. I don't know if that is something I need to worry about in this circumstance. Another chemical removal is done with a chromic phosphoric solution but I don't think I want to go down that road. Finally, I could just try sanding the finish off. I have no idea how hard that would be to do and I can't see how this would be better than what the NaOH and etching might do, but hey - I've never tried any of these.

Any suggestions on which method I should try, if any? FWIW this is saboil and the fuselage is connecting to carbon mast and carbon wings which have a finish on them, using stainless steel bolts.

Tangent - wondering if it's possible/worth adding an sacrificial anode?

fwiw, my first fuse was powder coated. Cheaper than anodization so more easy to reapply. Back to your question - we used to use oven cleaner to remove light anodization on bike parts. Don't know how effective it is on something that might have a heavier/better coat like a fuse.

Your instinct to expose more area is a good idea.
Oven cleaner usually gets it off, you may also need to do some sanding. I would keep it where the wings and mast mount if possible.

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Paducah said..
Tangent - wondering if it's possible/worth adding an sacrificial anode?

I might do this as well. The problem is that I would have to identify a place where I think it's safe to drill and thread a hole, along with countersink a hole for the anode. I can model the fuselage easily enough in a CAD program but I don't have a FEA package to look at forces and I would need outside help to counterbore a hole. Maybe a notch at the tail of the fuselage would work.

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shmish said..

Paducah said..
Tangent - wondering if it's possible/worth adding an sacrificial anode?

I might do this as well. The problem is that I would have to identify a place where I think it's safe to drill and thread a hole, along with countersink a hole for the anode. I can model the fuselage easily enough in a CAD program but I don't have a FEA package to look at forces and I would need outside help to counterbore a hole. Maybe a notch at the tail of the fuselage would work.

If you put any reasonable value on your time you will quickly spend more than the $360 the fuse costs from sailworks. Get them while they last, they are discontinued thanks to Kraken. I am on my second fuse, both of which I drilled and tapped for M8 wing bolts. The spots you show would not concern me. Mine pitted bad where the mast sockets into the fuse, that spooked me. I am currently exploring all carbon options..

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utcminusfour said..


If you put any reasonable value on your time you will quickly spend more than the $360 the fuse costs from sailworks. Get them while they last, they are discontinued thanks to Kraken. I am on my second fuse, both of which I drilled and tapped for M8 wing bolts. The spots you show would not concern me. Mine pitted bad where the mast sockets into the fuse, that spooked me. I am currently exploring all carbon options..

I might order a fuse but I just don't think I need one now and I want to avoid putting money into a dead platform. That, and the $360US is $480 cdn plus shipping and customs. I use this fuse with the 900 front wing which I think is a great wing. I've looked into carbon rod and wonder what kind of machining costs would be involved for machining a fuselage from rod, I think it could be cheaper to buy two brand new aluminum fuselages :)

Which fuse is this? I might have a solution for you in Canada. Let me know and I will send you a PM for a new one for less $$.

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utcminusfour said..
...I am on my second fuse, both of which I drilled and tapped for M8 wing bolts. The spots you show would not concern me. Mine pitted bad where the mast sockets into the fuse, that spooked me. I am currently exploring all carbon options..

That upper left spot is looking like it wants to crack so badly. Is the alloy in the SABFoil fuse the same as other brands or something that makes it more susceptible? Poor shmish's fuse looks like it has the plague. This is one thread where I'm happy that my primary spot is fresh water.

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shmish said..
I might order a fuse but I just don't think I need one now and I want to avoid putting money into a dead platform.

I feel you on the dead platform - same position myself on a nice foil.

Another way of making an anode is get some pure zinc sheet and cut out some shims to sit between the wings and fuselage.

They will eventually erode away but if you are dis-assembling each time you will see the rate of corrosion and change out accordingly.

www.ebay.com.au/b/Zinc-Industrial-Metal-Sheets-Flat-Stock/182928/bn_7116641826
www.ebay.com.au/itm/255559485015?hash=item3b80884657:g:kq8AAOSwTvNilG2o
www.ebay.com.au/itm/174314344488?hash=item2895f1d028:g:QukAAOSwXuRe4zWB&var=473416307312
www.ebay.com.au/itm/275192118807?hash=item4012ba7e17:g:v8oAAOSw0t5iIHCs&var=575465929608

Just make sure it's pure zinc, not zinc plated steel.

Clean off all the corrosion using a corrosion removal chemical or vinegar, neutralize acid with baking soda, and then paint with Rustoelum enamel paint, less than $10 for a quart, or use their automotive spray can enamel. Can contact them to confirm it will work, and how to prepare the surface. Just remember it will take 7 days to cure before putting in water, and it will degas the whole time, so do not leave in an area you will be exposed to it. Could put in spare bathroom and let vent fan run, that is what I did, but I have an adjustable speed fan so was not noisy. It is like an epoxy finish, hard and durable.

Clean, etch primer and then paint. While the paint adheres you know it is doing job. If it corodes again, repeat or replace. Zinc shim sounds good too.
Removing the anodising sounds like a big job, and the critical sections may just keep on corroding without a sacrificial anode with a higher galvanic potential. I think the only two metals are zinc and magnesium, with a higher potential then aluminium.

Don't NaOH (lye) or oven cleaner. Those are too alkaline and will etch the aluminum. At Boeing we used nitric acid to clean aluminum without etching it. Make sure there is no chloride since this also will etch the aluminum.

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ZeroVix said..
Which fuse is this? I might have a solution for you in Canada. Let me know and I will send you a PM for a new one for less $$.

This is the 1100 M6 fuse. I might be wrong but I think the only front wing it fits is the 900.

I had corrosion on my fuse. I sanded the affected areas back to clean aluminium, spray painted with etching primer and applied a couple of coats of acrylic paint. All good. If it happens again . I will repeat.

Make sure you give it enough curing time before using it in the water . at least a week from my experience.