Eisboch wrote:
"Tim" wrote in message
...



That's a very nice looking craft from what I can tell, but I wonder
what "Marine grade aluminum" is?

Some type of alloy? And I wonder how it would hold up to yearsa of
salt water and electrolysis?


Aluminum is made in many different alloys to achieve certain general
characteristics. I think the RockSalt boats are made of a series 5000 alloy
which has desirable attributes such as strength, weldability, and corrosion
resistance, particularly in marine applications.

Aluminum in general is a "self sealing" metal in terms of corrosion
resistance. If you scratch aluminum hard enough to get to the raw metal,
it quickly reacts with oxygen to form aluminum oxide on the surface of the
fresh metal. If I remember correctly, about 50 angstroms will form almost
immediately, then continue to build over time until the metal molecules are
no longer in contact with oxygen and the oxide barrier will stop growing.
BTW, aluminum oxide is non-conductive. That doesn't mean the boat won't
conduct electricity because the oxide layer is relatively thin (few microns)
and will break down at a high enough voltage. Often, though, low voltage
(like 12 volts) connections are difficult to properly make unless you
scrape off the oxide and make the connection before the oxide rebuilds.

Eisboch

I think that was kind of a problem with older Starcrafts, wasn't it?
I've seen many a Starcraft that was welded and patched upon. But at
least you could weld and patch them fairly easily.

"Tim" wrote in message
...


Eisboch wrote:
"Tim" wrote in message
...



That's a very nice looking craft from what I can tell, but I wonder
what "Marine grade aluminum" is?

Some type of alloy? And I wonder how it would hold up to yearsa of
salt water and electrolysis?


Aluminum is made in many different alloys to achieve certain general
characteristics. I think the RockSalt boats are made of a series 5000
alloy
which has desirable attributes such as strength, weldability, and
corrosion
resistance, particularly in marine applications.

Aluminum in general is a "self sealing" metal in terms of corrosion
resistance. If you scratch aluminum hard enough to get to the raw
metal,
it quickly reacts with oxygen to form aluminum oxide on the surface of
the
fresh metal. If I remember correctly, about 50 angstroms will form
almost
immediately, then continue to build over time until the metal molecules
are
no longer in contact with oxygen and the oxide barrier will stop growing.
BTW, aluminum oxide is non-conductive. That doesn't mean the boat won't
conduct electricity because the oxide layer is relatively thin (few
microns)
and will break down at a high enough voltage. Often, though, low voltage
(like 12 volts) connections are difficult to properly make unless you
scrape off the oxide and make the connection before the oxide rebuilds.

Eisboch

I think that was kind of a problem with older Starcrafts, wasn't it?
I've seen many a Starcraft that was welded and patched upon. But at
least you could weld and patch them fairly easily.

On Mon, 24 Mar 2008 15:05:55 -0400, "Eisboch" wrote:


"Tim" wrote in message
...



That's a very nice looking craft from what I can tell, but I wonder
what "Marine grade aluminum" is?

Some type of alloy? And I wonder how it would hold up to yearsa of
salt water and electrolysis?


Aluminum is made in many different alloys to achieve certain general
characteristics. I think the RockSalt boats are made of a series 5000 alloy
which has desirable attributes such as strength, weldability, and corrosion
resistance, particularly in marine applications.

Aluminum in general is a "self sealing" metal in terms of corrosion
resistance. If you scratch aluminum hard enough to get to the raw metal,
it quickly reacts with oxygen to form aluminum oxide on the surface of the
fresh metal. If I remember correctly, about 50 angstroms will form almost
immediately, then continue to build over time until the metal molecules are
no longer in contact with oxygen and the oxide barrier will stop growing.
BTW, aluminum oxide is non-conductive. That doesn't mean the boat won't
conduct electricity because the oxide layer is relatively thin (few microns)
and will break down at a high enough voltage. Often, though, low voltage
(like 12 volts) connections are difficult to properly make unless you
scrape off the oxide and make the connection before the oxide rebuilds.

Yeah- what he said.

"Tim" wrote in message
...


Short Wave Sportfishing wrote:
On Mon, 24 Mar 2008 11:03:09 -0700 (PDT), Tim
wrote:



Short Wave Sportfishing wrote:
On Sun, 23 Mar 2008 03:04:17 -0400, "Eisboch" wrote:

Have you seen these?

www.rocksaltboats.com

I haven't seen one as I don't think they've actually built one yet - I
think they are in process of building one, but I am aware of this
model.

From it's description, it's going to be quite the boat.

That's a very nice looking craft from what I can tell, but I wonder
what "Marine grade aluminum" is?

Some type of alloy? And I wonder how it would hold up to yearsa of
salt water and electrolysis?

When they say alloy, it's generally a percentage of magnesium and a
couple of other trace elements. Most aluminum boats are made from
5000 series aluminum/magnesium alloy - the differences are in the
amount of mgnesium per use specifications.

As to strength - almost forever. There was an experiment done by
ALCOA (which is referenced by almost all aluminum boat manufacturers)
WAY back when with long term exposure and they stopped the experiment
with the 5000 series aluminum because nothing happened - zero, zip,
nada.

The main problem with aluminum has been fabrication - for years (much
like steel as well), the only true way to built an aluminum boat was
rivets, but as welding techniques improved, it became viable to start
producing welded hulls with plate aluminum instead of sheet.

With modern etching, paint and powder coating techniques, aluminum
will last a long time with little or no corrosion.

Sounds good to me. I have a little dingy kind fo thing that was made
back in the 50's that was all rivet None of the strategic ones are
loose but some on the top side are. like the oar mounts and back where
the engine mount was.

I received the 2008 Princecraft 'Aluminum Fishing Boats' brocure a couple
weeks ago.
They claim to use 5052-H36 marine grade aluminum which is 25% harder than
competitors aluminum.
http://www.princecraft.com/Content/e...dvantages.aspx

Don White wrote:
"Tim" wrote in message
...

Short Wave Sportfishing wrote:
On Mon, 24 Mar 2008 11:03:09 -0700 (PDT), Tim
wrote:


Short Wave Sportfishing wrote:
On Sun, 23 Mar 2008 03:04:17 -0400, "Eisboch" wrote:

Have you seen these?

www.rocksaltboats.com
I haven't seen one as I don't think they've actually built one yet - I
think they are in process of building one, but I am aware of this
model.

From it's description, it's going to be quite the boat.
That's a very nice looking craft from what I can tell, but I wonder
what "Marine grade aluminum" is?

Some type of alloy? And I wonder how it would hold up to yearsa of
salt water and electrolysis?
When they say alloy, it's generally a percentage of magnesium and a
couple of other trace elements. Most aluminum boats are made from
5000 series aluminum/magnesium alloy - the differences are in the
amount of mgnesium per use specifications.

As to strength - almost forever. There was an experiment done by
ALCOA (which is referenced by almost all aluminum boat manufacturers)
WAY back when with long term exposure and they stopped the experiment
with the 5000 series aluminum because nothing happened - zero, zip,
nada.

The main problem with aluminum has been fabrication - for years (much
like steel as well), the only true way to built an aluminum boat was
rivets, but as welding techniques improved, it became viable to start
producing welded hulls with plate aluminum instead of sheet.

With modern etching, paint and powder coating techniques, aluminum
will last a long time with little or no corrosion.
Sounds good to me. I have a little dingy kind fo thing that was made
back in the 50's that was all rivet None of the strategic ones are
loose but some on the top side are. like the oar mounts and back where
the engine mount was.

I received the 2008 Princecraft 'Aluminum Fishing Boats' brocure a couple
weeks ago.
They claim to use 5052-H36 marine grade aluminum which is 25% harder than
competitors aluminum.
http://www.princecraft.com/Content/e...dvantages.aspx




It's all that Viagra they use to treat the aluminum.

"Short Wave Sportfishing" wrote in message
...
On Mon, 24 Mar 2008 11:03:09 -0700 (PDT), Tim
wrote:



Short Wave Sportfishing wrote:
On Sun, 23 Mar 2008 03:04:17 -0400, "Eisboch" wrote:

Have you seen these?

www.rocksaltboats.com

I haven't seen one as I don't think they've actually built one yet - I
think they are in process of building one, but I am aware of this
model.

From it's description, it's going to be quite the boat.

That's a very nice looking craft from what I can tell, but I wonder
what "Marine grade aluminum" is?

Some type of alloy? And I wonder how it would hold up to yearsa of
salt water and electrolysis?

When they say alloy, it's generally a percentage of magnesium and a
couple of other trace elements. Most aluminum boats are made from
5000 series aluminum/magnesium alloy - the differences are in the
amount of mgnesium per use specifications.

As to strength - almost forever. There was an experiment done by
ALCOA (which is referenced by almost all aluminum boat manufacturers)
WAY back when with long term exposure and they stopped the experiment
with the 5000 series aluminum because nothing happened - zero, zip,
nada.

The main problem with aluminum has been fabrication - for years (much
like steel as well), the only true way to built an aluminum boat was
rivets, but as welding techniques improved, it became viable to start
producing welded hulls with plate aluminum instead of sheet.

With modern etching, paint and powder coating techniques, aluminum
will last a long time with little or no corrosion.

Marine Grade is 5000 and sometimes 6000 but the important point is there is
negligible copper in the alloy. Not the amount of Magnesium.