Need help with an Aluminium boat

[Fidu666]

Hi guys

I've registered at this forum because me and my group (we're 4) have been dreaming about cruising for quite some time now, and have been looking at several boats all around Europe.

The latest one being a 16m Reinke in Italy which overall seemed to be in good condition but has issues with electrolysis on her hull apparently (along some of the weldings). We're currently in contact with a surveyor from Italy, which we have sent some pictures to, and he has raised concern. Also it seems that the boat has been on sale much longer than told to us by the seller and seems to be known since she has a blue hull, which he says is uncommon even for Aluminium boats, since not many people would paint an Alu vessel.

Can anyone tell me why he'd tell us that you would never paint an Aluminium boat in blue?

After reading a lot in the forum and gaining the impression that there's a lot of very capable folks around here, I'm gonna post a couple of pictures of her.

Every bit of help, thought or idea is appreciated. Thanks!

[Shrew]

I'm not clear whether he was saying:

1) It is uncommon to paint aluminum blue.

OR

2) That it was uncommon to paint a boat blue, and uncommon to paint an aluminum hull, making it doubly odd that an aluminum hull would be painted blue.

Either way, Blue hulled boats are very common in the North East part of the US. Maybe they are simply uncommon for that area. I would think a dark hulled boat could get warm in hot sunny climates.

Honestly, I've seen aluminum hulls painted as well. Who knows what he's getting at.

I'd be more concerned with the electrolysis.

[hpeer]

I agree with the above. I’ve no idea why it’s not wise to paint an aluminum boat hull blue.

It may have been painted because the welding was not well done and there is a lot of fairing on the hull. Conjecture.

Electrolysis is a major concern.

[rbk]

1) Its not electrolysis, if you're surveyor insists it is, get a new surveyor.
2) Hard to tell from the pictures but if there is bubbling/corrosion at the welds determine if it is just the paint or if in fact it is corrosion in the weld.
1)If it is corrosion, find out why (stray current, poor or improper weld)
3)The paint flaking/separation looks to be the bond of the paint failing, this can be a variety of reason original prep/paint job, age, physical damage, galvanic corrosion etc. If the paint bond is failing it should be repainted or it will continue to spread fast and further the longer it sits.

[Fidu666]

Originally Posted by rbk

1) Its not electrolysis, if you're surveyor insists it is, get a new surveyor.

The surveyor actually seems to know a lot about problematic spots of Reinke boats in general.

2nd picture shows the areas that worry him most, which are on the same place on both sides of the hull. The information that it actually is electrolysis came from the owner, not from the surveyor.

The surveyor said that he would like to sand off the paint on some spots to get clear vision, what do you think about that idea?

That the paint jobs on the blue have been improperly done is clear. Otherwise the paint would not peel off (I'm used to be a painter for quite some time). Upon purchase (if it happends) we'd remove the paint on the entire blue area.

[hpeer]

I had not picked up you were trying to show bubbling in the paint.

A few years ago I sandblasted and repainted the bottom of a steel boat. It blistered badly even before being launched. Factory insisted I must have had acids on the steel. Long story short I think I’ve chased the root problem to a nearby refinery emission. When I do the bottom near the refinery the paint blisters and fails. When I do it away from the refinery it is perfect.

[hpeer]

It’s above water line correct? What is the process for electroylisys above waterline?

Maybe there is a way it can occur above waterline, I don’t know it.

[Fidu666]

Originally Posted by hpeer

It’s above water line correct? What is the process for electroylisys above waterline?

Maybe there is a way it can occur above waterline, I don’t know it.

Its below the water line (in detail on the 2nd picture of my initial post), on both sides of the boat at more or less the same spot.

[rbk]

Originally Posted by Fidu666

The surveyor actually seems to know a lot about problematic spots of Reinke boats in general.

2nd picture shows the areas that worry him most, which are on the same place on both sides of the hull. The information that it actually is electrolysis came from the owner, not from the surveyor.

The surveyor said that he would like to sand off the paint on some spots to get clear vision, what do you think about that idea?

That the paint jobs on the blue have been improperly done is clear. Otherwise the paint would not peel off (I'm used to be a painter for quite some time). Upon purchase (if it happends) we'd remove the paint on the entire blue area.

Electrolysis - "electrolysis is a technique that uses a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction." like separating water into Oxygen and hydrogen. What he actually means is it is either stray current corrosion or galvanic corrosion.

[aquafacts]

Its likely were the lifting straps were (hence both side) on the hard chine. Paint was damaged on launch and left to corrode in sea water. With a open "sore" like that - any galvanic action is concentrated on the bare spot. Its - Aluminum so add some weld in the affected area and paint properly. **Use cardboard under the slings at the chines to prevent the problem from happening again !

[Uncle G]

The irregularity in the second image looks to me simply a slightly undercut butt weld and some thick bits of paint in places. As aquafacts says, use something to protect the chines from stretchy strops when launching.



It's hard to tell from the pictures, but I can't see anything I would worry about.

[rbk]

Originally Posted by aquafacts

Its likely were the lifting straps were (hence both side) on the hard chine. Paint was damaged on launch and left to corrode in sea water. With a open "sore" like that - any galvanic action is concentrated on the bare spot. Its - Aluminum so add some weld in the affected area and paint properly. **Use cardboard under the slings at the chines to prevent the problem from happening again !

This would just be oxidization.

[hpeer]

Originally Posted by aquafacts

Its likely were the lifting straps were (hence both side) on the hard chine. Paint was damaged on launch and left to corrode in sea water. With a open "sore" like that - any galvanic action is concentrated on the bare spot. Its - Aluminum so add some weld in the affected area and paint properly. **Use cardboard under the slings at the chines to prevent the problem from happening again !

These were my exact thoughts. Especially if the underlying barrier coat was compromised and the bottom paint had any copper.

BTW: you have a Goderich, I have a Murray 33, both Brewer designs.

[kazo]

here is a thread that is relevant - aluminum corrosion.
episode 19th plus thread on Sailnet;
https://www.sailnet.com/forums/cruis...end-dream.html

[rbk]

Originally Posted by hpeer

These were my exact thoughts. Especially if the underlying barrier coat was compromised and the bottom paint had any copper.

BTW: you have a Goderich, I have a Murray 33, both Brewer designs.

But they only painted above the water line.

I think (as mentioned above) that there was lack of material in the welds so they gooped on the paint. Painted aluminium eventually fails and has to be repainted, chances are they patched up some of the worse areas (most likely from strap wear) to make the sale go quicker/easier/more $$ and the current owner doesn’t want to deal with a complete paint and is letting it go before it gets out of control. Get someone to check those welds and reduce your offer to reflect the repaint, assuming the welds are fine and the surveydoesnt offer up any other major concerns. If you’re somewhat handy and can follow directions this is a job that can be done by yourself but would highly recommend paying someone to blast the old paint off.