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Old 02-05-2015, 16:23   #31
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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Originally Posted by Cheechako View Post
You need the Modulus of Elasticity for stiffness I think.
Oeps didnt get that one
I got ultimate tensile strength and yield tensile strength
figured anything with strength in it was the one to check
<-- Newbie lol
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Old 02-05-2015, 16:34   #32
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

UTS and UYS are measures of how strong a material is when being pulled on. Which is almost irrelevant to a rudder post. Young's Modulus is a measure of how stiff a material is.

As an example, rope has a pretty high UTS, but a zero YM.
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Old 02-05-2015, 16:40   #33
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

k modulus is:
316: 190 GPa
7075: 71,7 GPa
6082: 70 GPa
Guessin these figures are pro 316 lol
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Old 02-05-2015, 16:48   #34
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

I'll go with a full SS bar in 35mm and strengthen the pivot point on the transom
The diff would be 3,8 kg for the required length
And I'm pretty sure it will be strong enough

Thank U all for the help
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Old 03-05-2015, 09:01   #35
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

Try the scrap yards, you might get lucky
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Old 03-05-2015, 09:29   #36
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

This will probably sound heretical these days, but if you can't acquire the 316 stainless, you might consider RED brass pipe (not the same as regular brass) and bronze. My rudder stock is about 40 years old and is made from a length of red brass pipe and capped with machined bronze plugs. The plugs can be held in place with epoxy and pins. Using these metals, it was easy to braze on spines and fit plywood to shape the rudder, and then fiberglass it.

Although I use a lot of 6061-t6 on my boat, I would never consider it for rudder stock, but that is just me.


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Old 03-05-2015, 11:10   #37
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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Originally Posted by SVJennie View Post
This will probably sound heretical these days, but if you can't acquire the 316 stainless, you might consider RED brass pipe (not the same as regular brass) and bronze. My rudder stock is about 40 years old and is made from a length of red brass pipe and capped with machined bronze plugs. The plugs can be held in place with epoxy and pins. Using these metals, it was easy to braze on spines and fit plywood to shape the rudder, and then fiberglass it.

Although I use a lot of 6061-t6 on my boat, I would never consider it for rudder stock, but that is just me.


If you go this route make sure what you are getting is specced as G C90500. This is a low zinc brass that is very durable and corrosion resistant. Alternatively you could probably go with titanium for less. Copper these days is pretty expensive.
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Old 03-05-2015, 12:26   #38
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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Thanks for the answer.
Prob is I'm in Europe. I checked around my country and all neighbouring countries, only found 1 supplier and he only delivers to companies.. And he doesnt even have it in stock (thats the supplier that could provide me with the 6m through another company)
It would cost me like 500 euro's for the pipe incl shipping, which I find a bit too much...
The 6,35mm wall is the odd one out. 2,5mm wall is the max size I can get all over.
Europe!? Where!? Andorra la Vells !?

Here around Pesaro (I) you may found many purveyors of fine steel, in deposit as large as a Walmart
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Old 03-05-2015, 12:52   #39
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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...you could probably go with titanium for less...
Pretty sure titanium is several times more expensive. Worse, the welding is critical and very expensive.
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Old 03-05-2015, 12:57   #40
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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Originally Posted by TheThunderbird View Post
Europe!? Where!? Andorra la Vells !?

Here around Pesaro (I) you may found many purveyors of fine steel, in deposit as large as a Walmart
Belgium
Do u have any Italian site where I can find this SS tube?
Shipping to Belgium is expensive but might be an option
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Old 03-05-2015, 14:51   #41
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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Bending moment isnt an issue, as the top part of the rudder is attached on the transom with a pivoting point which kicks the bottom part out of the water in case it gets hit (hope I'm clear in my explanation as English aint my native tongue)
Only the bottom part rotates for direction
I suppose that if you live by the North sea, your native language is Flemish/Dutch.
In case you can speak a bit of French, have you tried Weber Metaux ?

INOX

They sell in lenght as small as 1m.
(but sometimes, charge same price for 2m).
http://www.weber-france.com/2008/Acc...ber-metaux.htm
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Old 03-05-2015, 15:04   #42
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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I suppose that if you live by the North sea, your native language is Flemish/Dutch.
In case you can speak a bit of French, have you tried Weber Metaux ?

INOX

They sell in lenght as small as 1m.
(but sometimes, charge same price for 2m).
Depuis 1889, WEBER METAUX ET PLASTIQUES distribue et vend aux particuliers comme aux professionnels toutes sortes de métaux, plastiques et outillage
Flemish, but I do speak French.
TY, mail send
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Old 03-05-2015, 15:11   #43
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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Flemish, but I do speak French.
TY, mail send
Sorry, for mentioning Dutch, no offence intended.

I suggest you call them, much quicker than expecting an answer by mail.
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Old 03-05-2015, 15:24   #44
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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Sorry, for mentioning Dutch, no offence intended.

I suggest you call them, much quicker than expecting an answer by mail.
No offence received. I like to call myself a wordly citizen
And the flemish side of Belgian actually speak dutch, so u were correct lol
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Old 03-05-2015, 17:16   #45
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Re: 6061-T6 Aluminium vs 316 grade Stainless Steel

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Originally Posted by Terra Nova View Post
Pretty sure titanium is several times more expensive. Worse, the welding is critical and very expensive.
Compared to this type of brass G2 titanium is probably less. 90% copper alloys are incredibly expensive these days.

The titanium reference was really just a bad joke honestly. Titanium, like aluminium would make a terrible rudder stock. They don't have the stiffness for this application. Carbon fiber, or stainless would be far better.

In order of preference however I would go with:

Carbon
Duplex stainless
316L
316
...
Brass/bronze/aluminium/titanium/whatever else people suggest.

Absent a good reason to get into exotics I wouldn't bother. 316L tubing isn't that hard to source. Even if you bought it in the states and paid for shipping it wouldn't be that much.
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