Painting/cleaning an alloy boat
Printed From: The Fishing Website
Category: General Forums
Forum Name: The Boat Shed
Forum Description: Discuss all things boating.
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=132398
Printed Date: 29 Mar 2024 at 8:19pm
Topic: Painting/cleaning an alloy boat
Posted By: bricker
Subject: Painting/cleaning an alloy boat
Date Posted: 29 Nov 2019 at 6:04pm
I'm sure it's been asked before........but following the adage of "The only dumb question...."
Can you paint an alloy hull effectively to look presentable and not like a dog's breakfast, or can you clean it well enough to bring back the shine? I have had an alloy 5 metre boat for a couple of years - it's about 14 years old - and it's stained/discoloured. what's a the best way to rejuvenate it. Looking at possibly gloss black or dark blue on hull from waterline to rail, so to speak and white for cuddy.
I did get persuaded to buy a bottle of alloy cleaner/acid wash at the boat show and have had mixed results with a test run on the transom, to be fair. Probably my technique but the result, albeit cleaner and brighter, is a little streaky and not quite as good as I was looking for.
Just after a little advice and other folks experiences/dos and don'ts :)
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Replies:
Posted By: MATTOO
Date Posted: 29 Nov 2019 at 6:15pm
What's the boat. Year and storage conditions past and present. Put up pics.
And why do you want too?
------------- Just cruising in my now sweetas pimped out Southern 755 HT0!
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Posted By: ofthesea
Date Posted: 29 Nov 2019 at 11:09pm
My Bluefin was painted when new, they used to send them to a vehicle spray painter nearby. Upper hull and cabin painted in 1995 still looks pretty good.
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Posted By: bricker
Date Posted: 29 Nov 2019 at 11:43pm
Marco GR490 - pictures as above. Intriguingly it looks a heap better in a photo than real life!!
Staining is quite bad on rear half of both sides and on cuddy where someone has removed old lettering. I purchased boat 18 months ago from previous owner who had got it from new, it had sat in an East Cape bach garage for 10 years without going in the water. 60hp ETEC had only done 60 hours......now at 110 hours after last 2 summers. Kept outside but full cover during winter.
I have brought it right up to spec with full service, new bimini, clears and road cover. Repaired ply floor but looking to put alloy checkplate in. Furuno 688 sounder + iPad Navionics plotter; bilge pump.
I live in West Waikato and whilst it's a lovely craft for the single-handed or elderly person and also the Coromandel mussel farms and other inshore waters, it is not one for crossing the Kawhia or Raglan bars on any but the best days. Looking to up grade to something to suit the West Coast and therefore wanting to smarten up the overall package for a sale.
I'd also be intrigued to get feedback on what people think is it's value??
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Posted By: pjc
Date Posted: 30 Nov 2019 at 4:54am
could try a water/vinegar solution,wipe using rags as not to scratch alloy
Do not think painting will add value.
------------- Sex at 58.Lucky I live at 56
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Posted By: Steps
Date Posted: 30 Nov 2019 at 8:45am
The biggest thing that causes issues, espec patches including patches under paint etc is when stainless fittings are added (transducers lights etc) and are not insulated causing electrolysis.
After that is understanding that alloy corrodes/ oxidises (equivalent of steel rusting) very easy.. As it does so it, it forms an oxide. this oxide (unlike steel rust) has a very hard and attaches to the alloy very tight, with a molecule slightly larger than the alloy, creating a inprenatable barrier.. What we see as a grey dulling. If the surface is highly polished, this also creates a surface that is resistant, but not permanent unless sealed (say a clear plastic or paint) It is also very prone to staining from glues, crc and silicone lubes
or can you clean it well enough to bring back the shine?
Deal with that 1st.
Yes.. remove excess oxidation with a weak acid. citric out of the missus spice rack. a spoon per 1/2L water , keep wet for and afternoon. acetic acid or a very weak soln of phosphoric (rust kill).. the latter far faster and use with caution... test.
You may find using acid can be by past depending on how bad the surface is
Then wet sand with about 380 grit till about 3/4 back to nice looking alloy..then with 800. Depending on finish or going to cut with polishing rouge then with 1200.
Now machine buff with a rouge ( I prefer stainless) and use kero as the medium and a cloth polishing on the polishing machine.. big angle grinder size.
Can you paint an alloy hull effectively
yes.. important to degrease the surfaces BEFORE doing any sanding or polishing. Not doing so will 'grind any silcones/ waxes / oils into the alloy causing issues when painted.
Then as above sand back and finish around a 400 grit.. then send to a painter who will use a paint system (from etch to finish coat) .. or can pay them to pre/ sand. They use specialist high tech 2 pot car paint systems that require correct temps humidities to produce very hard and durable results
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Posted By: bricker
Date Posted: 03 Dec 2019 at 11:28am
Thanks Steps........what is a rouge? I asked at the local engineering supplies store and drew a blank!! Also, could you elaborate on the technique of 'wet sanding'........is that with just water or is that too obvious.
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Posted By: Steps
Date Posted: 03 Dec 2019 at 2:44pm
what is a rouge? I asked at the local engineering supplies store and drew a blank!!
Really??? They will have it on the shelf. Rough is abrasive polishing compound made into a block like a hard block of soap. Comes in many grades suitable for different metals and grades.. usually colour coded.. white being for stainless. Will be next to their cloth buffing wheels that go on bench grinders and drills.
Wet sanding is using a wet and dry sand paper with a lubricant like water or kero... it stops the sand paper from clogging up...use a quality paper.. ends up being far cheaper in the long run. When driling or cutting .. even wet sanding kero is the go.. but wet sanding you can go thru a lot..and generous water is near as good.
When using rouge, kero is a more a luber/ spreader. Now hi polishing alloy is different to stainless, iron, steel , paint etc.. Those you are basically wearing the top surface off to get the final finish. Alloy you 'work it so you keep the area polishing quite hot .. not warm hot.. to the touch. Since alloy has a lower melting temp and is malable, what you are doing is getting big heat into the top few layers of molecules, these semi melt and fill in the deeper fine scratches. Wear old clothes , polishing is a bloody messy job.
I have done many a V8 valley cover, holly and impco carbs, old Jowett bradford inlet manifolds that have laid in paddocks for 1/2 century+, mag wheels , and stainless flashings bumpers for 69 camaro ready to fit after a body rebuild and paint. And the fiberglass boat.. oh and the glass on the shower door... Over the last 50 odd yrs
Then wet sand with about 380 grit till about 3/4 back to nice looking alloy..then with 800. Will elaborate a little on that
When sanding most ppl will sands till every mark is sanded out then proceed to the next, finer grit. You do not have to... Get 80% the finer marks/ scatches out....which take say 3/4 of the deeper ones out. Then you go to the next finer to to get the scratches caused by the previous grit out.. this also makes the deeper ones even more shallow. And again next grit.. by this time the deeper scratches are so shallow they are starting to disappear. Then you cut with rouge and wheel... which as I describes above, sort of melts and fills these in.
Have i explained that ok?
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Posted By: Haularse
Date Posted: 04 Dec 2019 at 9:11pm
Thought you did really well Step's
I have stripped the paint off my boat, used a paint stripper. Worked well and gave a better finish than using a grinder. I bought all the bits to polish it to hopefully a nice shine.
It's an older hull so don't plan on getting it like glass but a nice shine I will be more than happy with.
I do understand it will be a messy and possibly longish job, but I am up for it.
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Posted By: bricker
Date Posted: 04 Dec 2019 at 10:22pm
Thanks for the explanations........is the abrasive polishing compound called "Rough" or "Rouge".......sorry, I'm a bit confused from the earlier posts!!
You've clarified things perfectly - just have to put it into practice!! When using water as the liquid medium in the process, do you use a constant trickle of running wateror merely wet the area at regular intervals??
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Posted By: viscount
Date Posted: 05 Dec 2019 at 5:14am
try alumiprep, if you can find it before you start but read directions properly.
------------- Calling fishing a hobby is like calling brain surgery a job - Paul Schullery
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Posted By: Steps
Date Posted: 05 Dec 2019 at 8:57am
do you use a constant trickle of running water or merely wet the area at regular intervals?? Constant trickle if on a concrete surface under foot...which dont mind getting messed up and stained. If on grass, just dip and rinse/ shake in the water and sanding build up off the paper. And when lifting out carry generous amount of water to keep the surface wet enough to flow off excess sanding build up. Will not hurt to occasionally give surface a light rinse with the hose and rag. Once you get started you will very quickly get the feel for it nps
alumiprep
this is a soln of phosphoric acid .. rust kill... fiber glass boat cleaner.. and a heap of other 'specialised' brand names... usually charging excessive prices
Very important when using any phosphoric acid product...rust kill whatever.. Pour out what you need and use from that container. Do not use from the original container... Any contaminates will react with the acid in the original container and neutralise it. Also its not going to burn your hands off... I can dampen a rag and wipe down the bottom of my 5.5 F/ glass hull and skin gets a little dry for a while.. others maybe far more sensitive thu DO NOT spill or drip it on you galvanised trailer.. it will instantly turn white and eat the galv away.. not good.
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Posted By: bricker
Date Posted: 06 Dec 2019 at 7:13am
Thanks Steps.......sage advice as always.
I can see what I'll be doing this weekend!! Just have to add the correct measure of elbow grease methinks!!
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Posted By: Steps
Date Posted: 06 Dec 2019 at 9:05am
The instructions above will take you to the piont of a mirror, and I mean mirror as in bathroom mirror finish.
You take it to which ever stage you wish...you may find a wet sand to 800 or 1200 will be what you are looking for... And on a small spot do a etch with phosphoric to give a clean grey look.
Its more a time thing than hard work... unless out in the sun.
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Posted By: bricker
Date Posted: 07 Dec 2019 at 10:15pm
So........armed with a varying assortment of wet and dry, I've worked on the hatch as I can remove it and work out the best grit and technique. Results good so far but I'm struggling to remove marks that appear to almost be etched onto the surface. They are only on the uppermost surfaces (or worst there IMHO). Would you recommend a coarser grit (I'm currently at 220) or a different course of action?
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Posted By: Steps
Date Posted: 08 Dec 2019 at 9:29am
...to remove marks that appear to almost be etched onto the surface...
These more 'deep' stains rather than scratches?
Try a small spot with 150 and sand up... Thu chances are they will be stains that have been etched into the alloy rather deep.
When getting into a resto project.. be it a muscle car, classic or even a boat...it is very easy to forgot you are working on a 2nd hand well used project, plus loose site of the end use.
My 1st realization was on a muscle car that was intended to keep long term.. turned out 40 decades..totally dismantled in the shed..chassis all sand blasted back, and I was about to start grinding off and smooth out the factory welds. M78 pointed this out at the time... do I want a trailer queen show car or something to put miles up on, drive in the rain, presents very well at a show and shine....
Rather than concentrate a lot of time on areas like this.. give a LITTLE extra elbow grease on each level of sand...and decide what you want to do towards the end of the build... You may very well find everything gets knotched back a little and all good.
You dont need to turn out a show stopper, chrome plated see your reflection , finish..
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Posted By: MacSkipper
Date Posted: 08 Dec 2019 at 11:17am
Steps wrote:
...to remove marks that appear to almost be etched onto the surface...
These more 'deep' stains rather than scratches?
Try a small spot with 150 and sand up... Thu chances are they will be stains that have been etched into the alloy rather deep.
When getting into a resto project.. be it a muscle car, classic or even a boat...it is very easy to forgot you are working on a 2nd hand well used project, plus loose site of the end use.
My 1st realization was on a muscle car that was intended to keep long term.. turned out 40 decades..totally dismantled in the shed..chassis all sand blasted back, and I was about to start grinding off and smooth out the factory welds. M78 pointed this out at the time... do I want a trailer queen show car or something to put miles up on, drive in the rain, presents very well at a show and shine....
Rather than concentrate a lot of time on areas like this.. give a LITTLE extra elbow grease on each level of sand...and decide what you want to do towards the end of the build... You may very well find everything gets knotched back a little and all good.
You dont need to turn out a show stopper, chrome plated see your reflection , finish..
| x2 - good points I actually thought about polishing my boat but after fishing yesterday and it looking like a slaughterhouse contented myself with a clean with carwash solution and clean the windscreen for first time. I may do but it is pretty good now may leave till winter in a few years as it is under a carport.
------------- Good fishing trip nothing breaks, great trip catch fish.
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Posted By: Steps
Date Posted: 09 Dec 2019 at 8:46am
Wind screen.. Meguires Quick detail..use as little as possble After a few 30 sec cleans on a screen that size, it builds up a protection.. wash the boat, stuff doesnt stick to the screen, dry screen with a towel to remove water mineral spots... Good on the clear shower screens to maintain as well.
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Posted By: Brad76
Date Posted: 03 Jan 2020 at 8:30pm
Painting can change the look of a boat.
It needs to be done right and even doing it right is not as good as leaving it unpainted.
Corossion seems to be a major problem on all alloy boats.
As Steps said, you need an etch a prkmer and a top coat applied.
The surtees cost the owner 7k to do and that was with it soda blasted first to remove the paint that was corroding the alloy
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Posted By: MacSkipper
Date Posted: 04 Jan 2020 at 6:27am
Looks nice but a lot of coin....I like to think the natural alloy corroded look is cosmetic and thats all why paint it then you have to maintain?
------------- Good fishing trip nothing breaks, great trip catch fish.
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