Aluminum Hull Corrosion
AL
through, on their aluminum boat?
I have a 4 yr old "SMOKERCRAFT" (Stiletto) that I have used in salt
water for the last 3 yrs, which I have carefully washed down
immediately following each & every use, at home, with soap & water.
The boat lives a pampered life in my heated garage on a trailer while
not on the water.
The aluminum is pitting/corroding/rotting through causing leaks.
It is only a matter of time that the boat will be scrap.
I have no problem with rivets: the aluminum itself is rotting.
I have spoken to a Dealer who has dropped the 'Smokercraft' line, due
to these same problems.
He feels that there was/is a problem with the aluminum used &
"Smokercraft" denies responsibility.
Is anyone else having the same problems with their aluminum boat;
"Smokercraft" or otherwise?
Please contact me privately if you have any feelings on this subject.
Al Palombo
eye...@att.net
Craig Maxie
corrosion. Without knowing more, my guess in your case might be the
former (galvanic)... caused by combining metals that are far apart on
the galvanic scale. That's why sacrificial anodes are so important -
THEY corrode instead of the boat. As you hinted, there is a chance they
used the 'wrong' grade of aluminium for the hull - 5000 series is the one
for marine use; 6061 can be used where it is not usually submersed in
salt water. Each series has different compositions/properties. Try to
determine what was used, and if it's a riveted hull, find out what they
are made of (and any other fittings). Good luck!
Bray Haven
>> water for the last 3 yrs, which I have carefully washed down
>> immediately following each & every use, at home, with soap & water.
>> The boat lives a pampered life in my heated garage on a trailer while
>> not on the water.
>>
>> The aluminum is pitting/corroding/rotting through causing leaks.
>> It is only a matter of time that the boat will be scrap.
>> I have no problem with rivets: the aluminum itself is rotting.
>>
the boat. Aluminum forms a coating of oxide that is pretty inert and helps
protect it. Depending on the type soap you used, you may be removing this
oxide coating. I've seen premature corrosion of aluminum where people used
acid based cleaners on it regularly which removes the al oxide film. Probably
not your problem, but a thought.
Greg Sefton
P.C.
Also check if you use copper based bottom paint, as that _do not_ go well with
aluminium hulls.
You can find very old Alu boats that done well and hardly have a spot corosion,
but it's like if it go wrong, --- then it go wrong real bad.
Test the rivets to se if they could caurse the trouble, as what you say they
don't suffer, they maby could be wrong cast.
I know that Hempel have a special line of paints esp. for Alu crafts, and they
made into a science using only the right paints and treadments, ---- othervise
you shuld test if any other of what the boat are made of can produce acids.
Leaking accumulators or heavyli charged accumulators making acid fumes maby.
Also you can get chemicals like the "silica gel" packets that dry the air inside
the boat. Done proberly placed with a bucket underneath, this can remove any
water that could transport electricity inside hull surface, while the boat is
stored a maby damp place.
Look out for bronce propellors and replace any bronce or brass fittings with Alu
or first class Stainless.
------- Anyway get Hempels papers on Alu boat maintain .
Best regards
P.C.
Bray Haven skrev i meddelelsen <20010218083027...@ng-fl1.aol.com>...
Bray Haven
the hull.
Greg Sefton
P.C.
Can't emagine ; what's the reson grounding an electruc system in a boat, ----
that's just asking for trouble.
I know cars work with that , and unfurtanally it is cheaper with car parts, but
then ; what side cortod, the plus or the minus side ---- That work in any
application that the material as far as I remember, travel from minus to plus so
_if_ ground is minus then no wonder.
-------- On the other hand when current are build up from some time, and the
source are suddenly not there , will any current then go the other way ???
Or if ions art packed close to a surface and the building up current suddenly
are gone, will the surface then svitch polarity ??
--------- It _must_ be bad to ground the el-system in a boat, and for what
reson.
Best regards
P.C.
Bray Haven skrev i meddelelsen <20010218194917...@ng-ff1.aol.com>...
DRP
Hi Al,
You might want to consider 'painting'
the hull with epoxy to seal it and the
applying a few coats of good paint. If
the wrong type of aluminum was used,
this might be the only hope to stop the
corrosion and add a few more years to
your boat.
Best of luck,
Donald
--
I'm building a Steel Robert's 434. You
can sneak a peek if you wish by clicking
on me link below.
http://personal.lig.bellsouth.net/lig/d/_/d_r_p/homepage.htm
'USA, Home of the best
politicians money can buy'
Bray Haven
>Can't emagine ; what's the reson grounding an electruc system in a boat, ----
I used to have a marina, and you'd be amazed at the people who wired their
Aluminum boats that way. Just took a common ground for the small electrical
stuff like bow lights and depth sounders, bilge pumps etc, rather than taking
the trouble to run everything to a terminal block. Some of those showed
serious corrosion problems; esp if they were kept in the water (electrolyte)
:o).
Greg Sefton
Cheryle Thompson
Craig Maxie <0107...@3web.net> wrote in message
news:3A8E9918...@3web.net...
> The two big killers of an aluminium hull are galvanic and electrolytic
> corrosion.
If there is not a lot of "meat" to the plating there is no margin for error.
Be vigilant
Is the hull bonded to an engine block that is acting as the earth for the
electrical system? Stray electrical current from an incorrect electrical
hookup could be your culprit. You should always run an insulated circuit
(+) and (-) to all electrical and electronic components. ***do not*** use
the hull and engine block for the return path. A battery - or a battery
charger wrongly hooked up to your boat can supply all the energy required to
leave you the proud owner of a collander.
> Without knowing more, my guess in your case might be the
> former (galvanic)... caused by combining metals that are far apart on
> the galvanic scale.
For such rapid corrosion on a "dry" boat I'd first check for direct contact
between dissimilar metals. In the case of aluminium direct contact with
virtually everything except your zinc annodes will cause rapid corrosion.
The further apart on the scale the more aggressive the corrosion. Ensure a
non-conductive gasket isolates every item. This includes fastners
**wherever** possible.
Is the hull in contact with a steel trailer? Does the antifouling contain
copper? Is the (iron) engine block electrically bonded to the hull? Is
there a bronze propeller or through-hull? Even stainless fittings will
corrode ali.
Check. Then check if connectivity is likely under damp conditions.
(indirect contact through a conducting layer of seawater) Check the
bilges. I have seen major damage from spilt mercury and the copper in a 2
cent piece.
>That's why sacrificial anodes are so important -
> THEY corrode instead of the boat.
Make sure your zincs are bonded to the hull. If your zincs aren't corroding
they are not protecting your hull.
Cheap insurance.
As you hinted, there is a chance they
> used the 'wrong' grade of aluminium for the hull - 5000 series is the one
> for marine use; 6061 can be used where it is not usually submersed in
> salt water. Each series has different compositions/properties. Try to
> determine what was used,
In a marine environment 5000 and 6000 series alloys are o.k. They are
corrosion resistant. Avoid 2000 and 3000 series alloys.
>and if it's a riveted hull, find out what they
> are made of (and any other fittings). Good luck!
The good news - at least you are not berthed in "hot" marina.
G.
David Flew
Many years ago my father had an aluminium boat ( a tinnie down here). Not
painted, used in salt water, and sometimes washed out - but that's the norm.
Pitting corrosion and a few small holes after a couple of years.
The manufacturer asked if the boat had been stored under trees - apparently
some trees give off corrosive sap/leaves/berries. Not so. When they looked
at the boat, they identified the problem as being incorrect grade of rubber
used between hull and stiffeners - conductive, hence source of electrolysis.
They drilled out all the rivets, removed the rubber, replaced it and
re-rivetted the ribs, welded up the holes, and charged the sum of .....
nothing for the repair.
I'd forget the soap, just wash off the salt, pick out all sinkers, hooks,
bottle tops, and any other metalic junk.
Have YOU been in contact with the manufacturer - I'd give him the benefit of
the doubt until he rejects your request for assistance. Even if he won't
help fixingh it, at least he might help in definitive analysi of the
problem.
David
Craig Maxie <0107...@3web.net> wrote in message
news:3A8E9918...@3web.net...