Type of Aluminum for Marine Environment
 

I recently purchased a Questus self-leveling radar mount off of Ebay.
Unfortuantely this unit was designed to be mounted on a backstay, and my
boat (a Freedom 40/40 with a carbon fiber mast) doesn't have one. I've
designed an adapter for it, which I will machine out of 3" round Al stock.

It seems that there's primarily 2 types of Al stock available: T6511 and
6061. The part will be painted. Which of these (or some other varient)
should I use considering the salt water marine environment?

-- Thanks, Geoff

6061 is fine

http://tinyurl.com/4t3yh

Bill

"Geoff Schultz" wrote in message
7...
I recently purchased a Questus self-leveling radar mount off of Ebay.
Unfortuantely this unit was designed to be mounted on a backstay, and my
boat (a Freedom 40/40 with a carbon fiber mast) doesn't have one. I've
designed an adapter for it, which I will machine out of 3" round Al stock.

It seems that there's primarily 2 types of Al stock available: T6511 and
6061. The part will be painted. Which of these (or some other varient)
should I use considering the salt water marine environment?

-- Thanks, Geoff

In article Xns95B371897FDFAgeoffschultzorg@
204.127.204.17, says...
I recently purchased a Questus self-leveling radar mount off of Ebay.
Unfortuantely this unit was designed to be mounted on a backstay, and my
boat (a Freedom 40/40 with a carbon fiber mast) doesn't have one. I've
designed an adapter for it, which I will machine out of 3" round Al stock.

It seems that there's primarily 2 types of Al stock available: T6511 and
6061. The part will be painted. Which of these (or some other varient)
should I use considering the salt water marine environment?


T6511 is a specific heat treat designation for 6061. 6061
does fine in a marine environment. IIRC 5086 is the
preferred alloy for fuel tanks, etc, but is more commonly
seen as sheet and plate.

Ned Simmons

Geoff Schultz writes:

Which of these (or some other varient)
should I use considering the salt water marine environment?

Alloy 5456

http://www.key-to-metals.com/ViewArticle.asp?ID=99

Hey Geoff,


5052 is good, and sort of available. Easy to work with, an used for
fuel tanks too, and can be welded.

It is just a formed "L" bracket you need isn't it? I have to wonder
why you don't go with marine grade stainless though. Gage-to-strength
versus aluminum would keep the weight aloft very close, and would be
the material of choice I would think.

What point or height are you going to mount it? Masthead? Spreader??

Take care.

Brian Lawson,
Bothwell, Ontario.
XXXXXXXXXXXXXXXXXXXXX
On Thu, 02 Dec 2004 16:09:38 GMT, Geoff Schultz
wrote:

I recently purchased a Questus self-leveling radar mount off of Ebay.
Unfortuantely this unit was designed to be mounted on a backstay, and my
boat (a Freedom 40/40 with a carbon fiber mast) doesn't have one. I've
designed an adapter for it, which I will machine out of 3" round Al stock.

It seems that there's primarily 2 types of Al stock available: T6511 and
6061. The part will be painted. Which of these (or some other varient)
should I use considering the salt water marine environment?

-- Thanks, Geoff

Brian Lawson wrote in
:
The adapter has to accept the 2.5" long shaft of the self-leveling radar
mount and fit within the existing round housing. Basically this will be
a 3" long x 3" diameter rod. Then I'm going to mill 2 flats along
another 3" length of it down to 1.5" thick and bolt that to the existing
radar platform. That much stainless would weigh too much.

-- Geoff


Hey Geoff,


5052 is good, and sort of available. Easy to work with, an used for
fuel tanks too, and can be welded.

It is just a formed "L" bracket you need isn't it? I have to wonder
why you don't go with marine grade stainless though. Gage-to-strength
versus aluminum would keep the weight aloft very close, and would be
the material of choice I would think.

What point or height are you going to mount it? Masthead? Spreader??

Take care.

Brian Lawson,
Bothwell, Ontario.
XXXXXXXXXXXXXXXXXXXXX
On Thu, 02 Dec 2004 16:09:38 GMT, Geoff Schultz
wrote:

I recently purchased a Questus self-leveling radar mount off of Ebay.
Unfortuantely this unit was designed to be mounted on a backstay, and
my boat (a Freedom 40/40 with a carbon fiber mast) doesn't have one.
I've designed an adapter for it, which I will machine out of 3" round
Al stock.

It seems that there's primarily 2 types of Al stock available: T6511
and 6061. The part will be painted. Which of these (or some other
varient) should I use considering the salt water marine environment?

-- Thanks, Geoff

"Geoff Schultz" wrote in message
7...
I recently purchased a Questus self-leveling radar mount off of Ebay.
Unfortuantely this unit was designed to be mounted on a backstay, and my
boat (a Freedom 40/40 with a carbon fiber mast) doesn't have one. I've
designed an adapter for it, which I will machine out of 3" round Al stock.

It seems that there's primarily 2 types of Al stock available: T6511 and
6061. The part will be painted. Which of these (or some other varient)
should I use considering the salt water marine environment?

-- Thanks, Geoff

6061-T6 is about the commonest form of extrusion (such as pipe, channel,
T's, etc. - I guess 3" round bar is one of the extrusion forms
5086, 5052,5083 are the common forms of plate
5456 is pretty uncommon though it has higher "as welded" strength

Uhh, you're not planning to put this right on your mast are you Geoff?
Aluminum and carbon fiber get along like, well copper and aluminum.
Basically the potential for the aluminum to disappear is very high. If you
do this, make sure you insulate the two. One simple way is a couple light
layers of E-glass on the mast to isolate the CF.


--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)
You don't need to paint any of these alloys unless you want to.

"Evan Gatehouse" wrote in
:


"Geoff Schultz" wrote in message
7...
I recently purchased a Questus self-leveling radar mount off of Ebay.
Unfortuantely this unit was designed to be mounted on a backstay, and
my boat (a Freedom 40/40 with a carbon fiber mast) doesn't have one.
I've designed an adapter for it, which I will machine out of 3" round
Al stock.

It seems that there's primarily 2 types of Al stock available: T6511
and 6061. The part will be painted. Which of these (or some other
varient) should I use considering the salt water marine environment?

-- Thanks, Geoff

6061-T6 is about the commonest form of extrusion (such as pipe,
channel, T's, etc. - I guess 3" round bar is one of the extrusion
forms 5086, 5052,5083 are the common forms of plate
5456 is pretty uncommon though it has higher "as welded" strength

Uhh, you're not planning to put this right on your mast are you Geoff?
Aluminum and carbon fiber get along like, well copper and aluminum.
Basically the potential for the aluminum to disappear is very high.
If you do this, make sure you insulate the two. One simple way is a
couple light layers of E-glass on the mast to isolate the CF.

This will be mounted onto an aluminum radar mast on the stern of the boat.

-- Geoff

On Thu, 2 Dec 2004 23:58:31 -0800, "Evan Gatehouse"
wrote:

Uhh, you're not planning to put this right on your mast are you Geoff?
Aluminum and carbon fiber get along like, well copper and aluminum.
Basically the potential for the aluminum to disappear is very high. If you
do this, make sure you insulate the two. One simple way is a couple light
layers of E-glass on the mast to isolate the CF.

Hmm, I never considered this. Are you saying that carbon fibre is a
good conductor and that aluminum is "less noble" and therefore prone
to corrosion when directly affixed to carbon fibre in the presence of
current?

I mean, I learned the hard way about using fibre washers between my
aluminum spreaders and my SS deck light mounts, but in my mind I think
of carbon fibre as being in more or less the same class as fibreglass,
i.e. an insulator. I gather you are saying it's more like a conductive
metal...
R.

"rhys" wrote in message
...
On Thu, 2 Dec 2004 23:58:31 -0800, "Evan Gatehouse"
wrote:

Uhh, you're not planning to put this right on your mast are you Geoff?
Aluminum and carbon fiber get along like, well copper and aluminum.
Basically the potential for the aluminum to disappear is very high. If
you
do this, make sure you insulate the two. One simple way is a couple
light
layers of E-glass on the mast to isolate the CF.

Hmm, I never considered this. Are you saying that carbon fibre is a
good conductor and that aluminum is "less noble" and therefore prone
to corrosion when directly affixed to carbon fibre in the presence of
current?

I mean, I learned the hard way about using fibre washers between my
aluminum spreaders and my SS deck light mounts, but in my mind I think
of carbon fibre as being in more or less the same class as fibreglass,
i.e. an insulator. I gather you are saying it's more like a conductive
metal...
R.

Right - if you have it in contact with aluminum, the aluminum disappears
quickly.