Lol etec

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Ixneigh
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Lol etec

Post by Ixneigh » Sun Jun 12, 2016 8:12 pm

So I was cleaning the outboard stuff while swimming today and inspecting the bracket, and rudder hardware. When I looked at the prop I noticed that the prop nut and washer are bronze. Really?? Holding on an aluminum propellor. It had been painted black but after investigating the corrosion around it closely, I coujd see that it had a nice deposit of crud on it, and the black paint had gone away revealing the yellow color. No bad corrosion under the crud because I've got serious zincs. But I think it should be stainless steel. Can I just get a stainless crown nut like that easily?
Ix

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Gazmn
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Re: Lol etec

Post by Gazmn » Sun Jun 12, 2016 10:12 pm

While I want to say yes, I paused when I realized, most of my nuts are bronze :?

Hmmm...
:wink:

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kadet
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Re: Lol etec

Post by kadet » Mon Jun 13, 2016 6:16 am

I would say the nuts are brass and brass is less galvanic reactive with aluminium than stainless, so why would you want stainless?

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Ixneigh
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Re: Lol etec

Post by Ixneigh » Mon Jun 13, 2016 7:36 am

I was under the impression that stainless was better then bronze around aluminum. Like, I never ever use bronze screws in aluminum, and bronze winches must have a insulator pad when used on a mast.
The brass HIN plate on the back of the boat is eating up the aluminum rivets holding it on.
Perhaps there is some good reason they used bronze I don't know maybe they were thinking a stainless nut could cause galling when attempting to remove but never seize could remedy that.
It may not even be the original nut for all I know.
Ix

On edit I was thinking brass and bronze were about the same on the galvanic scale.
if the shaft is stainless though why add another metal type?

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aviro
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Re: Lol etec

Post by aviro » Wed Jun 15, 2016 10:11 pm

I cant tel you if it is the good metal for corosion but be caraful with etec.
i was shure the etec was the best...
mine broke ar 230 hours 1 fuel injector fail.
it was kiking from many hours mabe from the beguening and i was thinking it was the fuel
i ask the company to repair on the waranty same if it was expired from a couple of months,
they told me to send it and they was to arange that ok for me.... o yea
it cost me 650$ to fix it. They told me they paid 50% of the part but they charge me almost the double the price i was paid if i by the piece myself.
to resume they are not beter and be carefull, investigate by yourself
l'm goingto check mine... bronze with stainless shaft and aluminium prop...i dont like that
good luck

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kadet
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Re: Lol etec

Post by kadet » Wed Jun 15, 2016 11:13 pm

Stainless steal has a galvanic index of -30, brass has -40 and aluminium -90

You want the least deviation between two metals i.e. 50 between brass and aluminium vs 60 between stainless and aluminium

Neither are great but brass is slightly better. Just look at your stainless bolts on you spreaders or mast.

I would wager it has nothing to do with galvanic reaction and all to do with thread strength. A stainless steel nut could strip a stainless shaft if crossed threaded. Whereas the brass nut would strip before the shaft. Mush easier and cheaper to replace a nut than a shaft :)

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seahouse
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Re: Lol etec

Post by seahouse » Thu Jun 16, 2016 1:50 am

Stainless steel used in a location where it is in constant contact with water (ie below the water line) is bad news (and not the best choice of materials if you are looking for longevity). There might be some specific stainless alloys (not the common ones) that are an exception, with other compromises.

You won't find many such fittings made from stainless. Look around the marina at boats on the hard and you will notice that the majority (maybe all) through-hulls and fittings (which are critical components - you don't want them failing) are made of bronze for the purpose of corrosion resistance and longevity. Bronze will be around long after a stainless part has pit-corroded away. That is mostly for fittings not in contact with other metals, so that is another variable in the mix.

Ix, I would not change to a metal different from what was factory-supplied, especially if the part has not seen significant corrosion.

:wink:

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seahouse
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Re: Lol etec

Post by seahouse » Thu Jun 16, 2016 1:55 am

Also note that a layer of grease (dielectric or other) is always recommended on the shaft when changing the prop/ nut. I think that is a detail significant to this conversation.

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Ixneigh
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Re: Lol etec

Post by Ixneigh » Thu Jun 16, 2016 7:10 am

Huh well ok then !
This board is great
Thanks to the added zinc I put on the engine and brackets, there was no damage however the nut was coated in a crusty white stuff that flaked off easily.
The first year I had the boat, the bracket showed obvious corrosion. As did the engine lower unit.
None this year at all.
Ix

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seahouse
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Re: Lol etec

Post by seahouse » Thu Jun 16, 2016 8:41 am

The motor is tipped up normally? (Realizing that some of it and the brackets will still be submerged). Where did you add your extra zincs?

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Jonair222
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Re: Lol etec

Post by Jonair222 » Thu Jun 23, 2016 8:14 pm

i've been told i have brass nuts,
but i guess bronze nuts are good too

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