Corrosion under flooring on Alumaweld Intruder?

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kmorin
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Re: Corrosion under flooring on Alumaweld Intruder?

#26

Post by kmorin »

giddy , if it were mine I'd strip her down, turn her up and TIG overhead but then I have the facilities to get that done so its very easy to say and very hard to get done.

The pits and MIG welds you show are going to be a problem the scale of the welds is way out side the needed weld, but all that can be done with MIG- which all welders of aluminum boats will confirm are too big.

The entire keel area of the bottom will become softened and I can't predict the outcome of more huge MIG welds for your skiff.

My opinion is to find a TIG welder to move ahead. The welds should be in proportion to the pit not to the weld wire size and minimum puddle for 0.045" wire burning out the pits' bottoms.

just my take, and I do know that the implications are not pleasant, but having been there, done that , (AND) written articles about just such issues on the wwweb.... I can only say marine surveyors are there; between the buyer and the seller (and the bank) for a reason.

[And I mean knowledgeable, experienced in welded boats, and reputable surveyors; not the plastic yacht guys who don't know metal or skiffs. I only know a few, personally, and they're worth their weight in heavy, rare, and precious metals. ]

Your "bilge rot" is the result of a poorly executed build, and poor maintenance on top of that, then the 'cure' is left to the guy who ends up with all the foregoing problems. Not the best situation but that's where your pictures lead me to believe we are in this sad story.

I see the foam you're describing as the tank bedding and my opinion of the builder has dropped to a new, all time low.

Cheers, (and you may well feel like "splicing the main brace")
Kevin Morin
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Re: Corrosion under flooring on Alumaweld Intruder?

#27

Post by giddy »

Thanks Kevin, the machine that they had hooked up when I got there was a tig but he was adding a lot to it he said because of the corrosion? I was never good at tig so I don't know what to look for. As for turning it upside down that is not going to be a possibility specially since it is a hardtop, I don't think anyone could do that here reasonably :hammer: . I purchased this wonderful project (not realizing it was a project) a 1.5 years ago from a dealer in the Puget Sound area who claimed no electrolysis or corrosion. What a lucky surprise I got when I took the flooring off this year! I have never left it in the ocean and washed it down with freshwater and salt a way after every outing.

My plan as you stated is to clean all the large pits with a carbide burr bit and then acid wash then have them TIG weld it and I will confirm they will be tig welding the bottom and I will let them know the welds should be much smaller closer to the pit size. I think this is all they are capable of around here.

Also by saying, (and you may well feel like "splicing the main brace") are you suggesting I give up? I can't do that!

Thanks for all the help and if I missed anything let me know!
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Re: Corrosion under flooring on Alumaweld Intruder?

#28

Post by aitkenkingfish »

i would also dubble check all your wiring & make sure they havnt grounded anything to the hull. the lund alaskan I just purchased had a bad spot of swiss cheese I just got finished welding. when I rewired the boat I found out they had grounded all the electronics to the center console. which caused the ground to run thru the hull causing pitting issues which turned into holes.
kmorin
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Re: Corrosion under flooring on Alumaweld Intruder?

#29

Post by kmorin »

giddy if you put a cutting burr in the pits, there is no need to acid wash, until after all cutting welding sanding is done the last, very last step before leaving the boat bare, or painting is etching.

The welds look huge for TIG but they may not understand the most effective technique for repairing pit sites but that large of a weld repeated over a big area will soften the entire area, so if possible get them a 'cleaner' pit to weld- use the drill bit or carbine burr to gouge to clean metal if possible.

The technique for welding pits is to light next to the pit not on it. Then when the clean puddle is formed; allow the puddle edge, NEVER the arc, to flood the pit and that will float up any debris left, and then add filler into the lead edge and flood the pit up, don't put the arc on the pit or the puddle will gas up heavily and therefore require 'tonnes' filler.

They may be using more and more filler to get the bubbles an 'pepper' out. (under the hood the burned 'junk' floats up and look as black spots so the term pepper)

If the welder aims the tungsten near the pit with the high frequency (assuming it can be adjusted and they're using an inverter not a transformer??) up very high; the arc cone (footprint of the amperage transfer) will be narrowed and deeper than if the welder holds a long arc using a wider arc cone. IF the high frequency is fixed at 60Hz as in a transformer instead of an inverter, the arc will 'wander' or 'run to' the edges of the pit instead of staying where the weld needs to be; next to the pit but not in it.

A short arc length, combined with the higher frequencies (200Hz or more if possible) should be combined with an indirect burning/flooding/cleaning/fillilng of the pit. By melting clean metal and adding filler to the lead edge, the overall heat of the weld will lift the pit's impurities to the top but.... if the arc is directly heating an uncleaned pit the water and other contaminant will vaporize like a tiny volcano and even the argon/helium/cover gas will not always clean the puddle. The key is to do this weld along the edges of a puddle, the filler being fed low into the puddle and the arc staying back, and not put the arc over the pit UNTIL its bottom floats up.

The correctly done weld is pretty distinctive, start the weld, add some filler and let the puddle EDGE carry over the pit and the 'junk' should come up, then maybe a bubble opens and closes then, (and only then) the torch can be over the pit and only a few dips of filler are used.

Once the pit floods with clean filler, the entire debris clump (pepper spots) will bubble up and flood onto the puddle top to washed off by gas. The welder can then immediately lower the amperage to allow the puddle bottom to chill and add just one or two last drops of filler. Let the puddle chill by backing down the slider/foot pedal/roller heat control in a four to six count, if the puddle sags in the middle too much? then bump up the heat just enough to put a last dime on top, the welds you show used (way) too much filler and too much heat and were too large- overall.

At least that's my take. I did 1700+ (lost count) electrolysis pits overhead on a 30' landing craft and many of the pits were much larger than any you show. My method keeps the repairs in scale with the pit, as much as possible.

Last welding advice, if the pit prep cleans the area but the weld (still) 'blows up' its better to stop welding and add some more mechanical clean-up than to keep welding until a huge welds you show are left.

Any way you look at this welding; its a pain in the stern.

just my few cents.

Cheers,
Kevin Morin
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Re: Corrosion under flooring on Alumaweld Intruder?

#30

Post by giddy »

Thanks guys, at one point there was something grounded near the transom there is an old rivet and ground wire there. I will spend tomorrow with a dremel and burr bit going through the pits and bring it back to the welders. I am going to print out your post Kevin and suggest they weld it per your instructions. I hope they don't take offense to the recommendations!
kmorin
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Re: Corrosion under flooring on Alumaweld Intruder?

#31

Post by kmorin »

giddy,
I'd say that printing my ideas and showing it to the welder is maybe 'counterproductive'? I think they'll find the idea of someone telling them how to weld "less than appealing"?

You could just review the concept and hope for the best but I'm concerned that you may offend your shop people and that isn't the best way to start the day!!

If you do it, bring a case of decent brew, and pint if it's on a Friday (but only if they're old enough to understand the gesture)? Maybe not? (and today the shop owner may get bent over your input too?) I don't want you to ignore shop protocol. If I were there, I'd come by and offer to show the welder 'something someone else showed me' and then let them try it. Discuss the concept as another welder, but the problem is since you're the one asking for the work, you kind of fall into the "not a welder category" So... if you show up with some written ideas, regardless if they may work, the welder may be less than receptive?

But I'd be a tad shy of handing a welder someones (written) ideas about their work!

Cheers,
Kevin Morin
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Re: Corrosion under flooring on Alumaweld Intruder?

#32

Post by giddy »

No I totally understand, I had decided to do the printing more for my reference before going to the shop and suggest how I would like it welded up per other boat welders input. However I do understand it could be taken the wrong way I definitely wont be demanding anything. I just don't want it welded up really poorly, I would like it done for good! They seem open to ideas, both welders Senior and Junior at different times that looked at it suggested just welding a plate over the top and I explained why I did not want to do that. They definitely thought my reasoning made sense and said they could and would tig weld it. The junior welder who just started on it Friday was hoping I could clean it up a little more so his welds would be much smaller I figured I could do that.

I know I hate falling into the non welder category. I have done a fair amount of MIG welding through college and on the dairy, but I am in no way a professional welder and my tig welding was never good.

Oh yeah my wife told me it would be a bad idea to bring in written suggestions :beer: sometimes she is even right!

Or maybe I won't suggest anything it will all depend on the situation when I bring it, either way thanks a lot for your help!

I wish you were closer too maybe I could have hired you! Lol
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Re: Corrosion under flooring on Alumaweld Intruder?

#33

Post by giddy »

Well to add insult to injury I figured I better crawl under the boat and check a couple of corrosion spots. Two were at the very back of the boat and not bad but I figured I should have them welded anyway. Then I went to the one about two feet from the back dead center in there was a spot of corrosion. I used the carbide bit and it went all the way threw! Yeah a hole in the bottom of the boat and then it started raining, what a day! :deadhorse:
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Re: Corrosion under flooring on Alumaweld Intruder?

#34

Post by kmorin »

giddy, I'm sorry to hear the hull had such deep corrosion that your tool pierced the hull- but on the 'glass is half full side' - it happened on the trailer; not afloat. That's where a hole in the hull can happen and just be frustrating and not 'overly exciting' like wondering if the bilge pump will keep up?

Rain is good; it rinses the bilges and with a 'drain' then it will just run out on the driveway so the hull is cleaner than before.

I realize it seems like there's no end in sight but at least you're not offshore in a blow with a rotten bilge panel.

Give thanks.

Cheers,
Kevin Morin
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Re: Corrosion under flooring on Alumaweld Intruder?

#35

Post by giddy »

I agree completely, I am glad I am dealing with it now. When I came in I told my wife I had good news and that I had a hole threw the hull. She just looked at me and said how is that good news. I replied I could have been out at sea when I found it.

Its funny how the outside doesn't really show much corrosion but that spot was all the way threw. I bet something copper sat in the bilge water there. Oh well just more fun.

Not sure if you have used any #12 x2" SS screws but that appears to be what is used to hold down my armor-tech flooring. I was going to use these
http://www.alliance-express.com/mss/mss ... em=WS0650A
but am not sure if the "A .156"" measurement would be correct for the #12 screws? I know for wood it should work, I am just not sure if the screws would cut through the nylon as well? Anyway I ordered a couple samples to try.

Thanks again if I am ever in your area, or your in mine, I will buy you a beer or case!
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Re: Corrosion under flooring on Alumaweld Intruder?

#36

Post by giddy »

So I was thinking about the fuel tank and there are three cross members welded across the top. There is flexible plastic between between the tank and crossmember. I thought if I used 5200 on the flexible plastic to the crossmember then to the fuel tank it should hold it in well? The crossmembers are welded to the long runners of the hull after I put the fuel tank back in. This picture shows the crossmembers resting on the tank with one upside showing the flexible plastic. http://i683.photobucket.com/albums/vv19 ... 3F1D93.jpg

This way it should be solid without the foam. There was corrosion between the foam and tank.
kmorin
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Re: Corrosion under flooring on Alumaweld Intruder?

#37

Post by kmorin »

giddy, 5200 is a double edged sword.

yes its good glue and should seal pretty well, but it often takes heat to 'let go' when an removal is planned; perhaps not the best technique for removing a tank?

Foam is not the best bedding material- as you've found out. It almost automatically forms corrosion sites and can break down into formic acid compounds that accelerate corrosion at almost unbelievable
rates.

Vinyl carpet runner, a product used in hallways to cover carpet from wear, works pretty good. It is a non-reactive elastomere that has ridges to help water run off, and is inexpensive but will form a 'grip' on the metals. It's not the best but will work. If possible the tanks should be mounted like an (inboard) engine, on isolated cantilever struts, but I admit this is not always easily done.

Welding in the tank? Why not put a bolt in the joint? I know tanks shouldn't have to come out often but.... a sleeved SS bolt is not poor practice, it does take more fab work than lighting the torch but it's something you can reverse by hand with a wrench or two.

Cheers
Kevin Morin
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Re: Corrosion under flooring on Alumaweld Intruder?

#38

Post by Chaps »

Kevin, you're a real trooper walking giddy through this, gold medal (and a brew) deserved :beer:
1987 24' LaConner pilothouse workboat, 225 Suzuki
Image
please view and like: https://www.facebook.com/bottompainting/
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Re: Corrosion under flooring on Alumaweld Intruder?

#39

Post by giddy »

Well like all fun things this is what I got back for $500 from the welders and the hole in the bottom is still there. Looks like Mig
http://i683.photobucket.com/albums/vv19 ... D02092.jpg
http://i683.photobucket.com/albums/vv19 ... 11CA8C.jpg
http://i683.photobucket.com/albums/vv19 ... 0A0E66.jpg

With a couple cigarette butts lol!
kmorin
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Re: Corrosion under flooring on Alumaweld Intruder?

#40

Post by kmorin »

giddy, OK its not MIG but it looks like it!
not that skilled of a welder all things considered. But.... bending over, kneeling down, working below the knees is not exactly the best position to try to TIG weld in this condition.

I wouldn't have attempted or accepted the job like that. I'd have insisted we roll the boat, regardless of the superstructure or work involved. If not: I'd have refused to do the work, so I wouldn't have been responsible for this low quality work.

At my advanced stage of making mistakes; I don't like to repeat them over and over.

The TIG welds show someone who was 'backing out' too quickly, and cratered more than needed. The porosity along the sides of some of the welds also fits what I already described so no need to go there.
One of the reasons to back out too quickly is that your entire chest areas is compressed -you're almost holding your breath- so when you come to the end of the weld you stop the weld too fast and make a carter in the end of the weld. This is simply poor welding, but very understandable in this position, the poor welding part is the lack of maturity to see the position problem and either insist you pay to position the boat to make good welding possible; or refuse to get involved.

Sounds harsh but that's my take.

Not every one is old and fat and proud- they'll get there, but now they're young and lean and bullet-proof. Time will adjust this in most welders- but not all.

Last- the density of the weld population, and the out sized scale of the welds also, has softened to some extent the entire keel zone.

I hope when you sand this off, the porosity is not too deep?

Cheers,
Kevin Morin
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Re: Corrosion under flooring on Alumaweld Intruder?

#41

Post by giddy »

Thanks a lot Kevin, as you suggested I will grind to get them lower then sand them down. I am glad you think they are tig because that was making me irritated since that is what I requested. I could have done the mig myself, not well but I can. Of course the hole through the keel wasn't welded but I have to bring it back for some of the flooring support brackets anyways. There are definitely bumps on the outside of the hull on some of the locations, they welded, and I plan on grinding and sanding those down on the outside also.
I wanted to send you a case of beer for helping me but the websites wouldn't let me ship toe Kenai is there another way, do you accept Paypal?

Thanks again
kmorin
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Re: Corrosion under flooring on Alumaweld Intruder?

#42

Post by kmorin »

giddy, I'm glad you're getting something out of our back and forth, but I do this so that others can avoid the countless mistakes I've made in the past, my memories of having questions and no answers is still vivid even after these three and some decades.

welder has to pay to mount and maintain the site, but we all get to enjoy it whether we contribute or not; so any donations should go to the website fund, not to me, and I think this site can accept PayPal? There is a "Support AluminumAlloyBoats.com" link at the top.

Thanks again for the offer, it's always good to hear what you write is helpful.

Cheers,
Kevin Morin
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Re: Corrosion under flooring on Alumaweld Intruder?

#43

Post by giddy »

Thanks, I donated to the site. When you sand and or grind the welds do you make them flush with the surrounding material? That's what I have started on the outside anyways.
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Re: Corrosion under flooring on Alumaweld Intruder?

#44

Post by giddy »

So I was going to cup brush the hull for all the really little white spots but I can't seem to find a .014" SS wire cup brush around here. Actually no SS cup brushes. It looks like Sears has a couple cup brushes in brass would these be bad to use on the aluminum?
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Re: Corrosion under flooring on Alumaweld Intruder?

#45

Post by paulh »

I'm pretty darn sure using a brass brush on aluminum that will see marine service is a huge no no! You'd basically be putting on a microscopic coating of brass and creating a nice setup for galvonic corrosion.

I'd say scotchbrite bristle discs would be the ticket. Image
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Re: Corrosion under flooring on Alumaweld Intruder?

#46

Post by giddy »

Yeah I thought it was a bad idea I just figured I would ask. Never seen a scotch brite bristle brush those look nice.
Thanks
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Re: Corrosion under flooring on Alumaweld Intruder?

#47

Post by giddy »

Ok another question I have a slight crack on the inside of my transom. I am going to have them weld it up should I grind a groove in the crack for them to weld? Also should I not grind down the weld flush after they weld it? They told me not to grind it down because it would just cause it to crack again, I didn't think that sounded right. They also welded a couple holes up from an old kicker and told me not to grind them flush otherwise they would pop out?
Last edited by giddy on Fri Mar 08, 2013 11:18 am, edited 2 times in total.
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Re: Corrosion under flooring on Alumaweld Intruder?

#48

Post by kmorin »

giddy, grinding welds down, or dressing the face or finishing a weld is usually reserved for specific places where the cosmetics and final appearance is the main reason for the piece. So generally finishing welds that removes the 'crown' is not common in aluminum welding.

There are several reasons why the former statement is true; but welds should not pop out of holes.
That implies the weld is only fused at the outer surface and is not a good commentary on the weld. However, without pictures or a full description of the material, method and location; there's not much besides over generalization that can be made.

If a weld is one sided, it's almost never dressed, but then some topsides welds from one side only can penetrate so well they're fine even when they're fully finished to a nice sharp line using a sander/grinder. So Rules of Thumb are not very useful, its a case-by-case discussion. We'd have to see or fully understand where all this took place?

Cheers,
Kevin Morin
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Re: Corrosion under flooring on Alumaweld Intruder?

#49

Post by giddy »

Thanks Kevin,

I just listened to them this morning I figured what's a little more smoke up my BACK SIDE. Plus I still need some things welded.

The transom weld was actually already welded ,by them, and I ground it down and could see the crack which became more pronounced when I brought it back to the welders. This is when they said I should not have ground it down. The crack is in the same spot although longer because I believe they started chasing it when welding. To me this leads me to think they didn't get good penetration.

I figured if I grooved the area they would be much more likely to get a better weld and penetration?

Thanks for the concurrence on the welds not popping out of holes. They could only weld from one side but it still needed to fuse to the parent material otherwise I could just jb weld it. :hammer: He went on to point out fillet welds on the hull and say see those aren't ground down. Oh well what can you do but say, I see.
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Re: Corrosion under flooring on Alumaweld Intruder?

#50

Post by kmorin »

giddy, the idea of creating a groove is to increase the amount of the two pieces of metal next to the weld that are exposed to the welding process- or melting metal. So a groove of some kind is always a good idea, not it can't be formed by the edges of two parent metal pieces being held together edge to edge.

If you are having the spot re welded, then cutting a groove the size of the thickness is always better than leaving the weld to lay on top of the parent metal. But the groove has to be cut not abraded, or cleaned if you use grinder because most hard grinding wheels will leave particles inside that 'blow up' or 'gas out' in the weld. TIG can hover over the weld long enough to remove those gas pockets; MIG rarely can.

If possible used use a solid carbide rotary cutter to make the groove because you're using the bit to actually cut shavings, thereby leaving a clean cut groove. Many people who grind weld allowances/groove/penetrations into joints leave the contaminants so they weaken the MIG welder's chance of success.

If there is a crack in the original that not next to an previous/original weld- I'd want to know why? That's the first question, not just welding over the problem- it sounds like a design problem? Then if the crack is next to on in an original weld, why is that? What defect is being displayed?

Finally when the repair is made, is a simple re-weld or replacement weld enough?

It is common practice to either drill out the ends of a crack in the field or to cut out the weld beyond its cracked ends. If this is not done then 'chasing' the crack usually follows.

Plugging drilled holes is a pain the stern. To do it right you have to make the hole a cone, so the arc (MIG or TIG ) will direct to the bottom and you can 'weld out' or stack the weld out to the surface. This means a 1/2 or 3/8" drilled hole in 1/2" or 3/8" thick metal should be at least twice that diameter (maybe as little as x1.5) to successfully weld it solid. TIG is the best, but the power required is a heavier water cooled torch running at 300 or higher amps and preheating is not out of the question.

All these steps to 'doing it right' may be outside this shop's experience or common practice?

Cheers,
Kevin Morin
Last edited by kmorin on Fri Mar 08, 2013 11:42 am, edited 1 time in total.
Reason: typo's
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