Aluminium Yacht Hull Cleaning

[Wideocean7]

Hi All
I’m planning on giving the hull of my aluminium yacht an aesthetic freshen up. Much work has been done internally and so I think it’s time to give her some external TLC when I slip her in a couple of weeks.

Hopefully the photo shows the widespread staining. I’ve had various suggestions to clean the hull including using a scourer (which didn’t do a thing) and a mild polishing disc for an angle grinder (which I’m cautious about not ending up with polish circles). I am not after a perfect shiny superyacht mirror finish. I love the utilitarian grey look so just looking for the most efficient way to remove the stain marks and give the hull a consistent finish.

I am going to give some Septone Boatcare Aluminium Cleaner a go tomorrow. It’s an acid based etching cleaner.

Any other smart, time and cost saving ideas out there from those with knowledge of aluminium hulls?

Cheers

[Baby tug]

I have a 36 foot aluminum trawler the aluminum brightener cleaners are the only thing that works and they work quite well , sprays some on With a pump up chemical sprayer straight out of the bottle do not dilute, wait a couple of minutes and rinse off repeat until you get your desired look it will be a light gray silver look ,Napa has a brand about $17 a gallon another auto parts store sells a product called purple power aluminum brightener ,I bought 25 gallons , I have probably 6 gallons left but my boat was very heavily oxidized and took quite a few applications

[Baby tug]

You’ll also have to understand aluminum boat’s are just that way , they’ll be blotchy and the women don’t like them , I personally love them wash them twice a year and that’s it no paint no varnish , I can put up with the ugly

[Rumrace]

Alkaline cleans aluminum. In fact it can make it disappear. All kinds of expensive dangerous packaging of alkaline. Cheapest is drain cleaner. When stainless in stuck to aluminum drain cleaner not penetrating oil works.
Different alkaline as are used to polish aluminum pre anodizing or anodize.
Water down the drain cleaner to 1/4 and rinse immediately after cleaning.
Gloves glasses.

[fstbttms]

You understand that the effluent from that thru-hull is simply going to continue to stain the hull, yes?

[Rumrace]

Fstbttms nice Big Eye mask. NAUI instructor here in the waters of preserved shipwrecks.

[fstbttms]

Originally Posted by Rumrace

Fstbttms nice Big Eye mask.

OTS Spectrum

[JPA Cate]

Originally Posted by Wideocean7

Hi All
I’m planning on giving the hull of my aluminium yacht an aesthetic freshen up. Much work has been done internally and so I think it’s time to give her some external TLC when I slip her in a couple of weeks.

Hopefully the photo shows the widespread staining. I’ve had various suggestions to clean the hull including using a scourer (which didn’t do a thing) and a mild polishing disc for an angle grinder (which I’m cautious about not ending up with polish circles). I am not after a perfect shiny superyacht mirror finish. I love the utilitarian grey look so just looking for the most efficient way to remove the stain marks and give the hull a consistent finish.

I am going to give some Septone Boatcare Aluminium Cleaner a go tomorrow. It’s an acid based etching cleaner.

Any other smart, time and cost saving ideas out there from those with knowledge of aluminium hulls?

Cheers

You're between a rock and a hard place, mate. It is the oxides that protect the aluminum, so it is really best to let it stay "stained". Sanding and using acids will remove plate thickness. It is that you celebrate the vessel's integrity by letting nature take it's course.

We've some good friends with a painted hull on their three-off aluminium cutter. He's an engineer with a very hard-working wife, who diligently re-paints the boat every 5 yrs. or so. It is a huge job, and it looks lovely. Very "yachtie". There are lots of alloy boats around, though, with bubbles of oxides pushing up the paint, and THAT looks awful.

Another couple has an Allures that has been left "au naturel", and I think that I like the oxidized look, with the stripes where the fresh water from the rains drains off. There is something very honest about it. There are a whole lot of unpainted aluminium work boats in the world.

Just my thoughts, ymmv.

Ann

[Wideocean7]

Thanks all for the feedback. I take on board the comments that bare aluminium hulls do show stains. I am of the school that likes the grey look. It does concern me that the "cleaning" products seem to be heavily acid based. The Septone product I can get here (or a car shop variation) is a hydrofluoric and sulphuric acid based etching liquid. I haven't found places here in Oz where Purple Power is sold but a quick look shows it's also acid based - this time phosphoric and sulphuric, which I am assume is also etching. My question is do these etching products degrade the hull? I would not want to tart up my yacht at the expense of thinner plate.

And on one posters question about stains from the toilet thru-hull. I'm a Lancastrian from the UK and to anyone who know that part of the world, our sh$t smells and looks like roses!

[Baby tug]

I don’t know how old your boat is mines 30 years old it hasn’t melted away , the boat was originally painted , At some point the paint failed and was sandblasted it has a rough texture because of the sandblasting not exactly what i like but it is what it is , Built all with quarter inch deck ,house ,Hull , It continues to oxidize overtime so once in a while you’ll wanna brighten it up , as far as I can tell the acid Brighteners don’t cause any harm , There are other things in it besides acid , straight acid does not work I tried that, I don’t remember exactly what the other chemicals are but without them it won’t work well Or at all , You’ll be very happy with the brightener it makes a big difference

[Rumrace]

I bought ingots of aluminum for years sent it to the extrusion company then to paint or coating. It was for street light poles. Toronto water front I have anodized brushed aluminum. Anodyne or anodizing sure defeats aluminum degrading. On rare occasion we want a chrome like finish. They used an alkaline bath. All I can tell you is it’s truly dangerous and the marine brightener is drain cleaner in a new bottle.

[Wideocean7]

Originally Posted by Rumrace

I bought ingots of aluminum for years sent it to the extrusion company then to paint or coating. It was for street light poles. Toronto water front I have anodized brushed aluminum. Anodyne or anodizing sure defeats aluminum degrading. On rare occasion we want a chrome like finish. They used an alkaline bath. All I can tell you is it’s truly dangerous and the marine brightener is drain cleaner in a new bottle.

Sounds as if I should stay away from this!

[Wideocean7]

I have a slight development on the hull. The image shows where I have removed the existing name stickers (I will be renaming her) and the finish beneath is almost mirror. If I don't do something with this area, wouldn't the old name be visible when the new name is attached? Or would the natural oxidation revert those shiny parts to the oxidised grey around it?

I have now used the acid etching hull cleaner which I mentioned above. It was a good exercise but to me the results are not worth the effort, especially when I am not looking for perfect and shiny. If it were simpler to wipe on/spray off (as the instructions say) and the result removed the stain marks somewhat, I would have continued.

I'm now going to have a go with some aluminium polish and a random orbital sander.

Ideas and comments are much welcomed and appreciated.

[Baby tug]

Originally Posted by Wideocean7

I have a slight development on the hull. The image shows where I have removed the existing name stickers (I will be renaming her) and the finish beneath is almost mirror. If I don't do something with this area, wouldn't the old name be visible when the new name is attached? Or would the natural oxidation revert those shiny parts to the oxidised grey around it?

I have now used the acid etching hull cleaner which I mentioned above. It was a good exercise but to me the results are not worth the effort, especially when I am not looking for perfect and shiny. If it were simpler to wipe on/spray off (as the instructions say) and the result removed the stain marks somewhat, I would have continued.

I'm now going to have a go with some aluminium polish and a random orbital sander.

Ideas and comments are much welcomed and appreciated.

you have to apply multiple coats , spray it on what for 30 seconds to a minute rinse off with a hose , you may have to do it six or eight times eventually you’ll get the look that you want , otherwise buffing compound and a high-speed buffer it will shine like chrome

[Wideocean7]

Originally Posted by Baby tug

you have to apply multiple coats , spray it on what for 30 seconds to a minute rinse off with a hose , you may have to do it six or eight times eventually you’ll get the look that you want , otherwise buffing compound and a high-speed buffer it will shine like chrome

Thanks Baby tug. I'll try repeated washes as you suggested. What I want to avoid 'though is that the marks from the old name stickers are not removed. For me that would look rubbish. As I'm a fair distance from any suppliers, I have to think ahead about what tools I can buy before I slip her in a week. If I assume the worst case (in terms of work) that the marks aren't removed, it seems that I will have to buff as you also suggested. That might lead to whole of hull buffing which I will do if needed to make it look right. I'm aware that I'm contradicting my earlier posts about not seeking a shiny hull, but I consider that a necessary consequence because of the name marks. Also buffing only the immediate area with the name marks alone sounds a half-baked solution if it's still visible and unattractive. Does this make sense?

So planning ahead in case I need to buff:
1. Can I buff the existing surface or does it need to be washed with something first to remove the oxidation and if so with what? I have the acid etcher and my web search suggests white vinegar - there are probably others.
2. Do you have any suggestions of buffing discs and compounds to use?

I have allowed a 4 day window to do this when I slip her. So I have time to get it right.

Thanks again for your views which are very helpful.

Cheers