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Old 22-03-2019, 12:01   #16
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Re: Need help with an Aluminium boat

Most standard production aluminum hulls leave topsides unpainted. There is a peculiar attraction to those builders and buyers to that freshly burnished aluminum contrasted with the boot stripe and a rub rail or sheer stripe.

Also, it's fairly easy to determine if the small bubbling paint is galvanic corrosion...chip it away a bit. Corrosion looks like corrosion vs. a inadequately prepared painted surface. Even if it's corrosion (less likely that far above the waterline), scrape and grind and sand those small sections, prep and paint it...blue? that's up to you.
Here's a paragraph easily researched on the net regarding prep:

Alodine is a chromate conversion process, and it's use requires that the metal be acid etched beforehand. It in itself acts as the primer.
ZnCr and acid etching primer basically etch and prime all in one step. They are also a chromate process, thus they provide the chemical thingy as well. Alumiprep or vinegar are not really required then, but if you did use one or the other you likely will have a better prepped surface.

As for the unpainted topsides here's a photo of one; and a photo of my topsides (painted because the hull is not up to production level fairness).

An aluminum hull and shaft can be determined to have a proper amount of sacrificial zinc easily.
Here's a link:
https://www.boatingmag.com/how-to/zinc-anode-failure

You can install a corrosion meter (see photo below, I always have trouble getting these photos to stay upright).
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Old 22-03-2019, 13:35   #17
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Re: Need help with an Aluminium boat

The general problem with the German Reinke yachts is that there are a lot of private builders; the quality of these private builders could is different and is hard to check. Especially aluminium needs the right skills to get good quality and a minimum risk of corosion!
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Old 22-03-2019, 14:45   #18
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Re: Need help with an Aluminium boat

Welding in aluminium, particularly plates of over 5 mm diameter, require the plates to be pre-heated before welding. If this is not done the welds are not strong enough, although they appear normal.

Aluminium when painted is cut off from the oxygen that gives it a protective coat of aluminium oxide..That is OK if the paint is good enough to keep the water away from the aluminium, as well as any other chemistry especially the products of organic as well as inorganic alkaline or acidic reactions, but if it is not--then it is far worse than having no paint at all.

Also--copper based anti fouling is not used on alloy hulls--it is only suitable for steel or fibreglass, as someone already pointed out.

I think there is a big CAUTION sign on this vessel. It needs an expert--and the Navy uses alloy hulls quite a lot--they would have such people. Maybe one could ask around--
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Old 23-03-2019, 05:25   #19
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Re: Need help with an Aluminium boat

I would suggest that dark paints are not used often on Al because any, inevitable, oxidation would show up more and be unsightly. That and two other issues: heat inside in the tropics and poor visibility particularly at anchor. White hulls stand out in the lowest light levels, dark hulls disappear and commercial fisherman in the third world mistake our mast head anchor lights for stars,

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Old 23-03-2019, 07:01   #20
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Re: Need help with an Aluminium boat

Quote:
Originally Posted by rbk View Post
1) Its not electrolysis, if you're surveyor insists it is, get a new surveyor.
Absolutely correct .... Not electrolysis .... Do not hire anyone who uses this term as it has nothing to do with corrosion on boats. No one trained in corrosion analysis would use that word in relation to corrosion on a boat. No way to tell from the photos, I suggest you hire a qualified corrosion analyst to inspect any aluminum vessel as they can be quickly destroyed by amateur electricians.

I also think Aquafacts hit the nail on the head with his comment about the the lifting straps.
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Old 23-03-2019, 09:58   #21
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Re: Need help with an Aluminium boat

Blue has nothing special in itself. What he meant IMHO that it is unusual to paint an aluminium boat.
Saying that, some are painted. Needs etching primer as a base to ensure that paint coats adhere to the hull without flaking.
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Old 23-03-2019, 13:34   #22
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Re: Need help with an Aluminium boat

Thanks so much for all your input guys.

It took away a bit of my concern as I have read nowhere 'walk away and leave the boat'.
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Old 23-03-2019, 13:35   #23
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Re: Need help with an Aluminium boat

Quote:
Originally Posted by boatpoker View Post
Absolutely correct .... Not electrolysis .... Do not hire anyone who uses this term as it has nothing to do with corrosion on boats. No one trained in corrosion analysis would use that word in relation to corrosion on a boat. No way to tell from the photos, I suggest you hire a qualified corrosion analyst to inspect any aluminum vessel as they can be quickly destroyed by amateur electricians.

I also think Aquafacts hit the nail on the head with his comment about the the lifting straps.
Sorry my bad, what the surveyor was actually talking about was corrosion and not electrolysis.
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Old 23-03-2019, 14:20   #24
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Re: Need help with an Aluminium boat

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Originally Posted by kmcshane View Post
Also, it's fairly easy to determine if the small bubbling paint is galvanic corrosion...chip it away a bit. Corrosion looks like corrosion vs. a inadequately prepared painted surface. Even if it's corrosion (less likely that far above the waterline), scrape and grind and sand those small sections, prep and paint it...blue? that's up to you.
We don't want to paint the boat upon purchase (ifi t happends), but just remove the existing paint.
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Old 23-03-2019, 18:10   #25
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Re: Need help with an Aluminium boat

get a surveyor on site. I was told, live in Maine USA, that blue paint is bad luck because the sea doesn't know the difference between the sea and the boat but that is just superstition. BTW I like twin keels. when it comes to bottom paint my cousin added five oz. of HOT chilli powder and five oz. of round up weed killer and after two years he only had to wipe it down.
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Old 26-03-2019, 12:37   #26
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Re: Need help with an Aluminium boat

We're in contact with Paul Fay of faymarine.com at the moment. Does anyone know (about) him?
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Old 26-03-2019, 14:59   #27
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Re: Need help with an Aluminium boat

You may have heard of this place called Greece? Full of people calling themselves Greek and claiming to have been master mariners and founders of Western Civilization?

Well, before they got deluded in following the carpenter god, the Greeks knew an awful lot about the Gods, including a sea god named Poseidon. Boats, all boats, are Poseidon's daughters and they are under HIS CARE. This is why a captain asks Poseidon's blessing to marry and care for one of his daughters, and to this day a wise caption will place a gold coin, his boat's bridal dowry, under the mast when it is stepped. (No, you don't CHRISTEN a boat, you have a proper pagan priest BETROTH you to it.)

Poseidon's color happens to be BLUE. And as any Greek can still tell you, NEVER GO TO SEA IN A BLUE BOAT. It is Poseidon's color, and he might get jealous and TAKE THE BOAT.

Very very bad juju to paint a boat blue. Perhaps in Italy they no longer have the story straight, aluminum doesn't matter. The only way that you could have worse luck would be by having another female about the boat. Poseidon might not like that either.

As to leaving ports on Friday...That's a Moslem Holy Day. *Poseidon* doesn't give a damn about Fridays. But unless you've got a mosque on your boat...that's another whole set of rules you might be breaking.
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Old 26-03-2019, 15:06   #28
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Re: Need help with an Aluminium boat

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Originally Posted by Fidu666 View Post
We don't want to paint the boat upon purchase (ifi t happends), but just remove the existing paint.
I can understand that intention, but do consider that one reason for painting alloy boats is to cover up the extensive fairing that was applied to cover up unfair plating. Perhaps there is a means of measuring this... surveyor should know.

Good luck.

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Old 26-03-2019, 21:27   #29
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Re: Need help with an Aluminium boat

https://www.amazon.com/dp/B008S0NMA4...detail_1?psc=1
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Old 27-03-2019, 00:04   #30
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Re: Need help with an Aluminium boat

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Been there, done that. But thanks.
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