Hi,

I was told that aluminum hulls will deteriorate due to the
interaction between the hull and the water, caused by
electrical activity. That some of the electricity used by
the boat will get to the hull, and then react with the water
causing the hull to break down and become thin in places.
Can anyone tell me more about that, and how it actually
takes place if it's true? Also how to reduce the process?
I was also told something about a sacrificial anode...what
is that about?

Thanks for any help!
David

Hi

skrev i en meddelelse
...
Hi,

I was told that aluminum hulls will deteriorate due to the
interaction between the hull and the water, caused by
electrical activity. That some of the electricity used by
the boat will get to the hull, and then react with the water
causing the hull to break down and become thin in places.
Can anyone tell me more about that, and how it actually
takes place if it's true? Also how to reduce the process?
I was also told something about a sacrificial anode...what
is that about?

Thanks for any help!
David

It is true that some of the first Alu ships was coroded away due to steel
wire used as rope attached to another warship in steel --- think the tale
say two mine sweepers was simply coroded away underwater this way , but this
is many years ago and many alu boats been build since then. The Alu used
for boatbuilding today is made for that, and all you need to know, is that
there are special paint systems and special clean Zink to be used with Alu
hulls.
P.C.

You also have to know how to implement the electrical system. Basically,
ground nothing to the hull.

If an Al vessel is built correctly and maintained properly, there is not
much that will outlast it - and the maintenance is minimum.

Bill

"P.C." wrote in message
. ..
Hi

skrev i en meddelelse
...
Hi,

I was told that aluminum hulls will deteriorate due to the
interaction between the hull and the water, caused by
electrical activity. That some of the electricity used by
the boat will get to the hull, and then react with the water
causing the hull to break down and become thin in places.
Can anyone tell me more about that, and how it actually
takes place if it's true? Also how to reduce the process?
I was also told something about a sacrificial anode...what
is that about?

Thanks for any help!
David

It is true that some of the first Alu ships was coroded away due to steel
wire used as rope attached to another warship in steel --- think the tale
say two mine sweepers was simply coroded away underwater this way , but
this
is many years ago and many alu boats been build since then. The Alu used
for boatbuilding today is made for that, and all you need to know, is that
there are special paint systems and special clean Zink to be used with Alu
hulls.
P.C.

wrote in message
...
Hi,

I was told that aluminum hulls will deteriorate due to the
interaction between the hull and the water, caused by
electrical activity.

This is the result of "electrolysis", which will happen on any boat. It
just happens on an aluminum hull a bit faster and over a bit more area.

There is no maintenance free hull material. Steel rusts. Wood rots.
Fiberglass develops blisters. Aluminum is prone to electrolysis. No matter
what you hull is you need to take steps to protect it. If the boat is used
only in fresh water and sits on a trailer most of the time then you
generally don't have to do anything. If the boat resides in salt water all
the time then you need to stay on top of it or your boat will disintegrate
in short order.

There are two basic approaches to combating electrolysis. The first, and
most common, is to provide a sacrificial anode, commonly referred to as
"zincs". They are called zincs because that is what they are made of. You
bolt these to exposed metal items on your boat and let the current flow
through them, which causes the anodes to be eaten away instead of the more
critical parts of your boat. This approach works great to protect stainless
steel, brass or bronze, as the zinc is significantly less "noble" than these
metals. They are not as effective protecting aluminum as the zinc is only
slightly less noble.

The other approach is to break, or at least minimize the electrical circuit.
A larger boat that is kept at a dock has a significantly greater risk as it
is in proximity to other boats, steel from the dock, or even connected to
Earth via a power cord. These paths will complete an electrical circuit
that the electrolysis can follow. Common approaches to the power cord issue
it to use an isolation transformer and a "galvanic isolator" on the safety
ground.

If you have a small aluminum fishing boat that is used in fresh water I
would think that the zincs on your outboard would be sufficient. If the
boat is kept in the water all the time you should consider bolting a large
zinc to the transom (it must be below the water line).

The effectiveness of the zinc degrades with distance, so if your boat is
long you may want to consider getting additional zincs up towards the bow.
Note that the zincs must make good electrical contact with the hull and
should not be painted. Plan on replacing the zincs every two years in fresh
water and every year in salt water.

Rod