Fixing severe pitting and holes on alu boat

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rasmuss
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Fixing severe pitting and holes on alu boat

#1

Post by rasmuss » Mon Jun 03, 2019 2:14 pm

So I got my first boat, a aluminium one, and now after one season, its leaking. I tore up the floor to have a look and there is deep pitting and one smal hole in the “grooves” at the bottom of the hull. The brown hole in the middle left of the picture is about 2 mm.
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Alot of posts I read says to weld it but I dont have a welder and it seems to be a big risk of creating a bigger whole. I was first thinking of filling more of less the entire groove withe epoxy but then I stumbled on to soldering that seems to be a more gentle option than welding. So Im leaning towards soldering.

What do you think, epoxy, aluminium epoxy stick or soldering?

There will be a different thread on why it's corroding.

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gandrfab
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Re: Fixing severe pitting and holes on alu boat

#2

Post by gandrfab » Tue Jun 04, 2019 5:12 am

I have seen this a lot in pontoon boat hulls, thin aluminum tubes. By the time they are brought to me it's not worth the effort to repair.
I'm looking forward to a correct fix on this issue.

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Re: Fixing severe pitting and holes on alu boat

#3

Post by kmorin » Tue Jun 04, 2019 4:55 pm

rasmuss,
not sure exactly on the "zoom" level of the image posted- lots of posters will include a coin or ruler or something for scale- so I can't really remark about this corrosion repair except in general terms.

First, I would not recommend you try to weld this material - AT ALL! what is shown is a corroded area of some alloy of aluminum, that now includes a host of different degraded compounds- none of which are metal- and therefore "it won't weld".

It is difficult enough to weld pure metal in its many forms; so this image is an example of what NOT to try to WELD!

TO help with repair/recovery/remodel ideas or suggestions it is necessary to
#1 see the image in context
#2 to understand the boat's construction and scantlings
#3 to know more about the contributions to the bilge and floors of the boat (construction details as in #2)

Lots of archives here to research too- however, this post is like the parlor game "Battleship" where you can't see an overview of the problem- no scale, no context, no location, no alloy; not much to go on!

Cheers,
Kevin Morin
Kenai, AK
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Re: Fixing severe pitting and holes on alu boat

#4

Post by Chaps » Tue Jun 04, 2019 11:22 pm

give it a light sandblast and fill with epoxy paste, about all you can do
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Krisinak
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Re: Fixing severe pitting and holes on alu boat

#5

Post by Krisinak » Wed Jun 05, 2019 8:30 am

how thick is the affected plate? i would think that is a factor in what process could be used to restore the boat.

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Re: Fixing severe pitting and holes on alu boat

#6

Post by abec » Sun Jun 09, 2019 8:06 pm

I’ve been there before wire wheel and die grinder and for bigger ares I just hole saw it out and patch it up

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Re: Fixing severe pitting and holes on alu boat

#7

Post by goatram » Tue Jun 11, 2019 12:38 am

You cant weld Corroded Aluminum. You need to Clean it with a Burr Bit mad to cut Aluminum. Amazon has them. EVERY SPOT OF BROWN HAS TO BE REMOVED. Then Acid wash it. Then Depending on Construction; Plate or Thin Riveted metal.

There are WAYS to repair. Chaps Said Light Sandblast but that will put sand everywhere. 5 YEARS AFTER he did my deck I had to pull and replace my fuel tanks. Found 10lbs of sand down there.

Again Prior to repairing it all of the Corrosion HAS TO BE REMOVED.

Also nice to know your location and make of boat.
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Re: Fixing severe pitting and holes on alu boat

#8

Post by Krisinak » Wed Jun 12, 2019 8:59 am

the OP has not returned to the thread to provide further info. maybe he has lost interest?

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Re: Fixing severe pitting and holes on alu boat

#9

Post by gandrfab » Wed Jun 12, 2019 9:26 am

Or the forum
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Re: Fixing severe pitting and holes on alu boat

#10

Post by Chaps » Wed Jun 12, 2019 8:50 pm

John
All that sand in your bilge came from my futile attempt to sandblast your decks! Needless to say I have not ever done that again in spite of several clients insisting they would pay any price . . .
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Re: Fixing severe pitting and holes on alu boat

#11

Post by kmorin » Thu Jun 13, 2019 11:50 am

This post is a speculation about the photo of the interior bilge corrosion shown in the OP. IT is speculation, not supported by anything more than my experiences and my take on the photos' implications.

If aluminum is bent at too tight a radius on the press brake die it will strain harden to a level that will actually crack or tear. So this post is about a speculation about pressing OR ROLLING creases, V's, stiffeners into various alloys sheets.

IF the boat in question has pressed or rolled pre-formed V's in the bottom panel as do many hulls of various builders' practices; what if the alloy and die radius combination left the metal at a 'pre-fracture' strain level? If this speculation is true (? and this is a big IF) then like Jetty Wolf's bent tank bottom radius corrosion failures (that too remains speculation on my part) ..... then the implication is that aluminum alloys that are subjected to bending in too tight a radius, while they may not fracture, may created a zone of alloy that has shifted its molecular level bonds so the parent metal is not as resistant to corrosion as the original sheet?

If the OP were to observe, report, share the locations of the corrosion in his hull in a wider angle image (?) and it became evident the corrosion was more commonly located along pressed in panel stiffeners (?) the possibility exists the forming of that alloy and thickness lead to 5000 (assumed) series alloy becoming more susceptible to corrosion due to the actual alloy changes in the deformation zone?

It is known and accepted that a 4 X Plate Thickness radius in the neutral axis of the bend of 5086 H-116 will not only change the tensile strength (radically increasing) but that a 1 or 2 Thickness bend radius will almost always result in metal strain hardening failure and cracking.

so, I'm speculating that if an alloy can changes its properties like desirable increases in tensile and hardness- AND that same alloy can have other alloy/molecular changes by being incorrectly formed. Can a marginally incorrect mechanical cold forming process cause marine alloy to shift its original molecular bonds in a way to allow an increase in corrosion susceptibility?

Just speculating from the photo in the OP and some of the other experiences we've had here, and read about online.

Cheers,
Kevin Morin
Kenai, AK
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Re: Fixing severe pitting and holes on alu boat

#12

Post by rasmuss » Sun Jun 16, 2019 3:22 pm

Hi Im so sorry I have not responded. I forgot to turn on subscription on the topic and did not get any notifications. I have a bunsh of new topics and I will try to answer any questions. This is my first boat so bear with me I seem to know nothing. I dont, in this context =)

Images of context attached. I hope the images show enough constrution detail. Otherwise let me know I’ll get more.
Images show the bilge. The floors where wood, probably pressure treated. There is also a picture of some old repairs previous owners have made.
I tried to measure the thickness, the only decent place to measure was above the waterline, but I think it the same. Thickness i 3mm.
I do not know what the alloy is, but I will post and ask in a swedish forum where the boat was manufactured. Manufacturing has stopped a while back.
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Old repairs
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kmorin
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Re: Fixing severe pitting and holes on alu boat

#13

Post by kmorin » Sun Jun 16, 2019 3:45 pm

rasmuss,

first reply is the corrosion is widespread and not confined to the rolled in V shapes in the bottom panel: that implies the entire bilge was flooded with an acid sufficient in ph to initiate many uniformly spaced sites of corrosion pitting OR a bilge that contained metal salts- like copper. The latter case means the corrosion came from galvanic corrosion not necessarily acidic corrosion.

The worst examples appear in the V's where bilge water was not drained and was allowed to concentrate the ph (lower) or galvanic solution? and do the most damage. At this stage welding has a very mixed chance of helping your corrosion repair. IF you can get a location with clean metal on all sides of a corrosion site (?) THEN the weld might span from good metal to good metal after you'd cleaned the corrosion site with a carbide burr (as Goatram recommends).

On the other hand - if you had treated wood or COPPER Impregnated Plywood... as decking the even rain water would leach the copper salts that are in that wood into the bilge and your corrosion is from a galvanically different solution not necessarily acidic solution.

In short if you did in fact have copper impregnated plywood for decking- and it rinsed into the bilge then the corrosion is not necessarily acidic as much as galvanic differential. I realize this is splitting hairs as the corrosion exists. But if you get rid of hte copper source, and rinse the bilge with soap and water- THEN ACID ETCH- you could at least arrest the progress of more galvanic corrosion.

A suggestion, above, is to sand blast/soda blast and then use an epoxy coating.... at this stage that is about the only realistic approach- as welding would involved too much area to be realistic.

Sorry you got involved with a boat that was so poorly maintained.

Cheers,
Kevin Morin
Kenai, AK
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Re: Fixing severe pitting and holes on alu boat

#14

Post by rasmuss » Tue Jun 18, 2019 5:11 pm

Ok, so summing up
Clean out with brush, sand blast, then also soda blast? and then a epoxy coating. You mention acid etching, should that be done after blasting and before coating?

About the existing holes, what would be the suggestion for plugging these? expoxy? durafix soldering?

About the reason for corrosion. It would be interesting to dig a bit deeper in this to ensure that i does not continue.
The floors where not plywood but planks.
If not the floor could it be from a broken battery?
No chance of electrolysis?
I have found some bits of stainsless steel in the bilge, could that have caused it?

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Re: Fixing severe pitting and holes on alu boat

#15

Post by kmorin » Wed Jun 19, 2019 1:06 am

rasmuss,
I'll try to correlate your summary to the posts in the thread somewhat?
rasmuss wrote:
Tue Jun 18, 2019 5:11 pm
Clean out with brush, sand blast, then also soda blast?
all these methods are used to achieve the same result, eventually. Brushing with SS brushes, sand blasting or soda blasting are all related to one piece of advice: CLEAN the existing corroded aluminum very thoroughly.

Sand blasting is a much more thorough way of power brushing aluminum. However, many abrasives (sand types) can be very aggressive and your bottom is degraded at this point.... SO soda blasting is the least aggressive of sand blasting media(s). Soda is extremely fine, soft and still has some abrasive qualities.

If an experienced sand blaster was doing the work (?) they would use lowered pressures (compared to new aluminum or other alloys) AND move the nozzle appropriately. I suggested soda blasting because without an extremely knowledgeable blaster - you'll blow through many (MANY!!!!) places in this highly damaged bottom.

SUMMARY: brushing, sanding, blasting and otherwise cleaning this hull is the first and critical step to any recovery. Blast media are available in wide range of hardness and that correlates to the medias' excavation of the material- corroded spots are softer, weaker and thinner. The least abrasive blast is "soda" blasting - like powder really.
rasmuss wrote:
Tue Jun 18, 2019 5:11 pm
You mention acid etching, should that be done after blasting and before coating?
Acid etching (usually a mixture of hydrofluoric, sulfuric, and hydrochloric acids [https://www.zep.com/product/zepcorporate/zep-a-lume] will excavate the corrosion sites and clean all the craters, pits and buried sites by reacting with the aluminum that remains in each location UNDER the corrosive cell's hydrates left from whatever was the corrosive agent.

The acid will lift the corrosive agent, the degraded hydroxide of aluminum resulting from corrosion left in the corrosion site pits and will also clean any surrounding aluminum of oxide - in preparation to a coating.

After etching, (before sand blasting) you rinse to dilute the acid and wash off that diluted residue. And you rinse and you rinse until you could flood the entire town rinsing. Once etched and rinsed- that is when you'd clean the bottom of each pit or site with and anchor pattern using a blasting media.

If you go to the expense of blasting you could skip the acid etch. I you don't do a soda/sand/grit blast (?) then use the acid to scour the metal including deep in the pits that are formed.

SUMMARY; etching could be a viable alternative to sand blasting. Sand blasting (particulate media blasting) can be an alternative to acid etching. What acid achieves is to wet down into the tiniest crevice where blast media may not go- to lift and float out the corrosive cell's active agents and resulting hydroxide salts of aluminum.
rasmuss wrote:
Tue Jun 18, 2019 5:11 pm
About the reason for corrosion. It would be interesting to dig a bit deeper in this to ensure that i does not continue.
In a previous post I thought you'd mentioned the wood might be treated and that i not an acceptable material for aluminum boats. The bilge may have been flooded with any number of contaminants?

Yes a broken battery could have made the entire bilge acidic enough to do what we see, but until you're able to do more exact research- the contaminant remains speculation?
rasmuss wrote:
Tue Jun 18, 2019 5:11 pm
No chance of electrolysis?
If by this term you mean "stray current" corrosion? then; yes if the boat was wired with a battery and didn't have that wiring connected correctly and the bilge was flooded- the battery could create wide spread corrosion sites in the bilge. However, stray current usually - not always- as a somewhat distinct wider open and conic crater appearance. This is just from experience and is not a Rule of Thumb... however the images show a bilge contamination that was A) wide spread in the bilge water & B) seemed to be a ph related corrosion? (however it could be galvanic - metal salts like copper in the bilge water too?)
rasmuss wrote:
Tue Jun 18, 2019 5:11 pm
I have found some bits of stainsless steel in the bilge, could that have caused it?
not sure the alloy of the SS you found, but SS would usually create a point galvanic- not dissolve in the bilge water and create and area wide problem? Copper washing out of treated wood would create a bilge solution to attack the aluminum, but metallic copper, by itself, or other galvanically different metals would more often create a reaction at a single point- not wide spread as your photos show?

Hope this helps clarify the discussion?

Cheers,
Kevin Morin
Kenai, AK
kmorin

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Re: Fixing severe pitting and holes on alu boat

#16

Post by kmorin » Wed Jun 19, 2019 11:59 am

rasmuss wrote:
Tue Jun 18, 2019 5:11 pm
About the existing holes, what would be the suggestion for plugging these? expoxy? durafix soldering?
The holes shown in the bottom of the V, rolled into the bottom panel/hull sheet of the boat could be fixed/repaired in a couple of ways.

First; If you can clean the metal around the holes so there is no corrosion on them, and drill out the actual corroded holes' wall or bore- then you might be able to weld using TIG (only)? I would recommend that someone with good experience do the welding as this is a 'non-trivial' exercise. The trick will be to achieve a short duration, small size weld involving the bored hole and tying to the surrounding metal- and that metal has to be sound enough, that is free of corrosion enough, to sustain a weld.

This method can work if there is good access to the boat's bottom- as that is where the weld will need to take place. If the boat can be inverted it will make the welds 100 X easier to accomplish in a short duration. If the welds are attempted from the inside of the boat- welding using AC TIG down inside those rolled V shapes will be much less successful as the arc will 'stray' to the sides of the V and make the work tedious as well as much less likely to seal a clean weld.

Welding from outside the hull, with her keel up, the puddle will 'sag' or penetrate into the hull and that will work to fill the void of the bored corrosion site AS WELL AS.... allowing inside reinforcement of the weld site.

Second; Epoxy/filler/chemical sealers could be used if the holes are 3/16" dia. or less- above that and there's a fair risk of the filler and surrounding metal not expanding and contracting at the same rates and therefore the seal being lost.

To fill with some form of liquid-to-solid sealer- the surface preparation is similar to welding or painting - cleanliness is the key. So the work of either acid etching or blasting or a combination of these methods is required to get much of any bond to the remaining aluminum.

To seal the openings or actual holes I'd prefer to go with something like 3M (tm) 5200 Marine Sealant in the hole and supported with a coal tar type of paint inside, once the holes were individually drilled and sealed with 5200. I don't think the 5200 will have a problem sealing if it is BACKED up or Supported inside by a film of a mm or two thick. After filling the hole, allowing the initial fill to cure, or just get firm- I'd add 5200 inside the rolled V so that it could adhere to the sides of the V to increase the sealed area.

If this sealing were done with boat's keel down? I'd use tape under the hull to form a dam to retain the sealant and then add an 1" or 2" inside the V to 'back up' the hole. Even cured 5200 is somewhat flexible and could therefore remain bonded to the metal in flexure from both heat and motion.

Using a bilge coating epoxy type of paint, will likely puddle/collect/thicken/pool down into the V's rolled in the bottom - which is where the holes appear to be located? If the surface was cleaned, the holes drilled to the smallest bit size that will clean the walls of each hole and that area was sealed with 5200- THEN the entire inside was epoxy coated; that's how I'd approach chemicals and paint method of filling these holes.

Others might have a better idea of methods?

As a note: the weld shown as a previous repair seems to show a weld that was done from inside the boat and the entire rolled/pressed V shape was filled as near as I can see? This method could work, but I'd caution about the two shoulders of the area to be filled would have to be 'sound' or clean metal. If there were corrosion pockets present- when the weld heated those areas remaining water or corrosion byproducts would turn to steam instantly and the parent metal would literally explode in a tiny volcano of molten aluminum!

So while that method may be a functional welding method- the conditions to make it possible depend on the state of the surrounding metal.

Hope to have summarized some of the previous posts and remarks into useful information.

Cheers,
Kevin Morin
Kenai, AK
kmorin

rasmuss
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Re: Fixing severe pitting and holes on alu boat

#17

Post by rasmuss » Wed Jun 19, 2019 5:21 pm

You are a god sent =)
Ok I’’l think I do like this please tell me if I’m making a misstake.

Im planing on doing in it two separate parts. First to get something out of this season I’ll fix the holes, then in autumn do the full epoxy coating.

So for fixing the holes.
1. Clean the entire bilge with a preasure washer to wash away any contaminents?
2. Drill out the holes
3. brush and acid etch the area around the holes
4. preasure wash again to rinse. Yay or god no!?
5. tape below the hole and fill with sealant
6. fill a long area of the V with sealant on top

Then in autumn
1. Presure washer
2. brush and acid etch the entire corroded area
3. Presure washer again to rinse
4. dry out
5. coat with epoxy

Some mixed questions.
You mention SS brush. Can I use that on aluminium? I read somewhere that SS particles will stick to aluminium and create more corrosion. Otherwise what brushwould you prefer?

As I say in my list I plan to do acid etch on the entire bilge after already sealed the holes. could that be a problem? dissolving the sealant?

There are many old repairs, including the big round blob of sealant in the middle. Just leave it as is?

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Re: Fixing severe pitting and holes on alu boat

#18

Post by gandrfab » Thu Jun 20, 2019 6:02 am

I wouldn't use 5200 to fill voids that are not fully covered. ie. plates, flanges, fittings.
5200 is an exceptional adhesive with proper prep work.
I have seen it wash out around through bolts and in my case I used it as fill and seal on my bow eye, trip after trip I checked and little by little the 5200 was washing away until it got to where it was doing its job as a sealer/adhesive.
I'm told paint doesn't stick to 5200, all though I know 5200 will stick to fully dried paint.

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Re: Fixing severe pitting and holes on alu boat

#19

Post by kmorin » Thu Jun 20, 2019 12:54 pm

G&R, I do understand that 5200 might not hold well in the bow stem area where there's some possible pressure or wash but.... I'd say it was the 'stickiest' and most flexible for small holes aft on the running surface? There, is no pressure there- at least not impact or bow wash. So small holes should hold as well as any rigid setting compound?

G&R were you thinking if using a rigid sealer like JB weld or Marine-Tex ? I've seen those series of compound have their own problems sealing- and 5200 at least remains flexible to some degree.

Rasmuss, once the sealant glue (5200?) is applied I would not re-etch the bottom or pressure wash again until you plan to remove the sealant.

To make the sealant work- drill out the holes as small as possible, etch/rinse/dry the boat if possible (assuming you're not blasting) and then wire brush (SS thin bristles 0.015" or thinner if possible) the area. SS is fine on aluminum- and I don't think there are any 'particles' of SS to leave behind? Steel brushes on the other hand do leave dust and it is reactive with aluminum. SS brushes power and hand both of alloy 304 with find bristles work well to clean the oxide film or disturb this film and will not contaminate the parent metal.

Some people would use a fine grit sand paper and that works to scarify and rough the surface too. 120-150 grit paper will clean the surface too- just make sure you blow off using shop air- any remaining dust and then acetone the area before adding calk.

Entirely wire brush to create an anchor pattern for the backing sealant to hold to the V groove of the bottom. Tape the outside and fill in the goop. Let it cure and then try to pull it out of the V groove? That is a test to see if the bond is adequate to give you a season's boating? If you test the adhesion by pulling on the sealant with pliers or vise grip pliers- then you can develop some 'feel' for the level of trust you can place in the temporary repairs.

IF: The holes are small and backed with a filled V groove and the sealant bonds to scarified,
cleaned, (I do suggest you pour or wipe Acetone over the area to be sealed JUST before applying the sealant)
warmed- (might use a small torch unless the weather is warm)
dry of any moisture;
THEN small holes like you show will fill and seal for at least a short time.

so the only question I raise is #4 in the first series- don't work to disturb the sealant bond after its applied.- except to test ONE site before doing the others. If you can pull the sealant free - the material to sealant bond is obviously not strong enough to seal the hull!

rasmuss, the boat is in dire need of real repair- not just some band-aide work to get in the water. I'd suggest you have a good bilge pump, handy bucket! and if possible a hull drain so you can keep any incoming bilge water - to the lowest limit possible!!

Cheers,
Kevin Morin
Kenai, AK
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Re: Fixing severe pitting and holes on alu boat

#20

Post by rasmuss » Sun Jun 23, 2019 3:37 pm

Ok so no I should not re etch once I fixed the holes, kinda make sense.I there any good way of doing the repairs in two steps? My plan was to first fill the holes to get some boating this season and then do the epoxy coating of the bilge in the autumn. Should I just try to clean it out with brushed before epoxy?

One more question. I have trouble getting zep a lume in my part of the world. What I can find of aluminium cleaner is wheel rim cleaner. Do you thing that will do it?

I read the discussion above about the 5200 hole fixing. Could there be an idea to use a some thing like epoxy or soldering to make a more "permanent" fix or will it just break apart?

And one last one =) You say the boat is in need of real repair. I that covering the bilge with epoxy or is it cut out the coroded and basically weld on a entire new back bilge? =(

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Re: Fixing severe pitting and holes on alu boat

#21

Post by kmorin » Tue Jun 25, 2019 9:42 pm

rasmuss,
rasmuss wrote:
Sun Jun 23, 2019 3:37 pm
I there any good way of doing the repairs in two steps?
Hard to say what's "good". I weld and have built boats for a few years, so good to me and good for you might be different answers.
rasmuss wrote:
Sun Jun 23, 2019 3:37 pm
Should I just try to clean it out with brushed before epoxy?
I'm not positive I'm following your question 100%? I think any repair- including welding or blasting then welding will include a bit of brushing just before the welds are applied?? I'm missing something in the question? if you put a single point of sealant, or wider area of epoxy to create a protective film of the damaged areas- all of those imply (TO ME) either blasting, sanding or brushing to get the metal rough - to create an anchor pattern (search online for this term) and to remove or abrade oxide film before attempting any bond to the metal- including welding, flexible or rigid sealants.
rasmuss wrote:
Sun Jun 23, 2019 3:37 pm
What I can find of aluminium cleaner is wheel rim cleaner. Do you thing that will do it?
rasmuss, I'm not sure of the cleaning agents in this wheel cleaner so I can't respond intelligently. I might ask if it will clean aluminum wheels- then it is implied it will clean an aluminum boat- the degree of cleaning is not something I can reply about.
rasmuss wrote:
Sun Jun 23, 2019 3:37 pm
Could there be an idea to use a some thing like epoxy or soldering to make a more "permanent" fix or will it just break apart?
I have not seen any repair except welding that was truly a permanent solution and as we've discussed that will be a very large undertaking for the boat in the condition shown. I am not familiar with soldering aluminum.
rasmuss wrote:
Sun Jun 23, 2019 3:37 pm
You say the boat is in need of real repair. I that covering the bilge with epoxy or is it cut out the coroded and basically weld on a entire new back bilge? =(
Airplane mechanics seem to repair airplanes with rivets- as they're originally built- they rely on what they know. Wooden boat builders tend to rely on more wood to do their repairs. Plastic boat builders seem to rely on more plastics and goops.... I am a welded aluminum boat builder so I tend to argue that method is the only permanent repair.

Cheers,
Kevin Morin
Kenai, AK
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Re: Fixing severe pitting and holes on alu boat

#22

Post by rasmuss » Sat Aug 03, 2019 3:47 am

Hi! some follow up here. I have now washed, brushed, drilled out, etched and filed the holes with marine glue goop =)

I just have a question regaring the acid etching. I have done acid etching on the area around the holes where I used the glue, to get a good surface gripp. Now it dawns on me, should I do acid etching on the rest of the corrosion damage even though Im not applying any epoxy or glue there? Could the acid etching stop any corrosion in progress? For example if the corrosion is due to copper in the previous wooden floor?
Last edited by rasmuss on Sun Aug 11, 2019 3:19 pm, edited 1 time in total.

alumioforte
Posts: 102
Joined: Sun Nov 27, 2016 8:08 pm

Re: Fixing severe pitting and holes on alu boat

#23

Post by alumioforte » Mon Aug 05, 2019 7:04 pm

Why not weld instead of glue?

rasmuss
Posts: 13
Joined: Mon Jun 03, 2019 1:51 pm

Re: Fixing severe pitting and holes on alu boat

#24

Post by rasmuss » Sun Aug 11, 2019 3:18 pm

In the discussions above I got the impression that trying to weld on the corroded areas would be unwise and the corroded area is too large to cut out. Any idea about the etching?

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gandrfab
Posts: 447
Joined: Fri Mar 28, 2008 12:33 pm
Location: Edgewater Fl

Re: Fixing severe pitting and holes on alu boat

#25

Post by gandrfab » Mon Aug 12, 2019 5:00 am

Cut out, replace is the answer when it is too corroded to weld.
Clean and patch is the 2nd choice.

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