Just wanted to let people know of a corrosion issue I have with a Streamlined aluminum extension right where the SS screws contact the aluminum (see pics). Treated with STABIL corrosion control and that stopped more white oxidized aluminum from forming. Always used in salt water and always washed with fresh water after each session. I wrapped the SS screws with 6-7 wraps of teflon tape. Have a newer Streamlined extension that I did the same for and no corrosion so far.

Now I did disassemble the extension once to clean out sand, maybe that affected a protective coating on the screws?

I think the ext. SS screw heads were holding saltwater between them and the aluminum during my sessions allowing electrolysis to occur. Taped screws with teflon tape, used nylon washers to separate the two metals, and sprayed everything with Boeshield T-9 corrosion protection which leaves a waterproof layer of wax. Will see how that works. The newer ext. (on right) had minor surface corrosion under the screw heads, see pics. Second pic shows reassembled ext. with SS washers and black nylon washers.

Bottom line, whoever designed this should have known the two dissimilar metals needed to be separated by a nylon washer. Glad I caught it early on the newer extension.

Decided to add nylon washers to the single bolt base screws as well, minor corrosion so far.

Used loctite blue on the single bolt base screws since the threads did not fully engage the nylox nuts.

this kind of corrosion would happen to all my streamlined stuff eventually. they would use anti-seize grease that was not tef-gel... if i were reassembling I'd use tef-gel and possibly augment w/ nylon washers as you did

The nylon washer will not do much apart from reducing Part of the contact area between the screw and the tube.

There is still the thread in contact which will still create a circuit.

Tefgel will alleviate this.

Another option is to remove the top cap, paint a bit of cold galv inside of the top of the tube, that should then become the sacrificial anode rather than the aluminium.

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elmo said..
The nylon washer will not do much apart from reducing Part of the contact area between the screw and the tube.

There is still the thread in contact which will still create a circuit.

Tefgel will alleviate this.

Another option is to remove the top cap, paint a bit of cold galv inside of the top of the tube, that should then become the sacrificial anode rather than the aluminium.

I wraped the top half of the screws with teflon tape, the screws have a loose contact with the aluminum tube versus the SS recevier on the inside of the tube. But I will check it in a couple of months to see if the corrosion stoped or continued.

You can paint some cold galv on the inside of the tube (where you can't see it) and the zinc in it should act nicely as a sacrificial anode rather than the aluminum

will see if the corrosion continues or not before doing anything more.