Welding a steel hull

"When you are doing awkward overhead welding and the flux is off the end of the rod , the only way top get started is to drag the rod and burn the steel back in the flux. Puting the work down every time and finding a piece of scrap to burn the steel back, then beginning again would add a huge amount of time and cost to a project, for no real gain."

No. If it were that difficult to solve the problem, reaching for another rod is a better solution, or does that cost huge amounts of time & money?

"The institutional nitpickers who advocate the later , often have little experience being in the awkward overhead welding position, but simply do their calculations on workbench work, and have little comprehension of the realities of building a small boat on a budget, limited in both time and money."

Well, I disagree & I probably have put in more hours overhead welding in the past year than you've done in the past 10, maybe 20. Your flogging a dead horse, here.

 

I am hoping for an explanation of how on earth that could possibly have any significant effect on any part of an 'average' steel yacht.

I dont think I would drag a rod just to get the flux back on it, but even so, I would still like to hear about any yacht that it made the slightest difference to.

 

"...I would still like to hear about any yacht that it made the slightest difference to.."...in a word, confidentiality!

You probably wont find any hard evidence (written), unless you're very lucky. Why?..not because it doesn't happen, it does, frequently. But because it is all an insurance claim and confidential.

I've had to go survey boats pretty much all over the world looking at structural failures, and also been passed projects to critique and review. All confidential and all showing and exhibiting just as describe above.

Which is why it is written into codes etc as being poor workmanship and registered as defects and requires corrective action.

 

I was going to argue the point again, until I did a google of the effect

http://www.disastercity.info/titanic/index.shtml

How about a warship that cracked in half like a glass bottle from a fracture caused by an arc strike ??

My jaw is still bouncing !!!!

 

Interesting article, but with a few errors.

Constance Tipper, at Cambridge University in the UK discovered this but her work was not fully appreciated until the 1950s. The charpy V notch test is what it has evolved into today.

Perhaps a few believers now???...or still think QA is a waste of time and money

 

There is no doubt that arc strike can lead to problems with the structural integrity of welded steel, but the debate is whether it's a 'significant factor' in steel boat construction. (BOAT not ship).

After a lifetime of designing, building and surveying steel boats, I would categorically state that in boats up to 65 ft LOA or more, it's only of theoretical significance and the lack of evidence to the contrary is not due to confidentiality, but due to there being no evidence.

What few failures I've seen in steel boats have been due to gross errors in design or construction. Over my lifetime, I've slowly come to the conclusion that the ONLY merit of steel as a boatbuilding material is quite how tolerant it is of poor workmanship.

The steel boat world is full of pig ugly, badly built, terrifyingly unstable, abominations, but I can't remember many that were structurally unsound. (This is in direct contrast to the FRP world). But that's why god made steel biodegradable - the bad ones quickly revert to their raw material; dust to dust, etc.

 

Quality, price, delivery.

pick two

 

"There is no doubt that arc strike can lead to problems with the structural integrity of welded steel, but the debate is whether it's a 'significant factor' in steel boat construction. (BOAT not ship)."

What I was debating was what you tell a person who is welding/building a boat for the first time, not degree of significance. If I still had access to a Brinell(hardness tester) I'd probably waste a weekend trying to come up with some definitive numbers. If anyone does have one at their disposal, I'm sure we'd all be interested in the results. Over all, I'd suggest that it should be considered in the same light as undercut. Significant undercut is a failure waiting to happen, yet, a small amount - how does one define "small amount"? - may have no adverse effects, depending on the other variables involved.

"After a lifetime of designing, building and surveying steel boats, I would categorically state that in boats up to 65 ft LOA or more, it's only of theoretical significance and the lack of evidence to the contrary is not due to confidentiality, but due to there being no evidence.

What few failures I've seen in steel boats have been due to gross errors in design or construction. Over my lifetime, I've slowly come to the conclusion that the ONLY merit of steel as a boatbuilding material is quite how tolerant it is of poor workmanship."

Perhaps, you are right & there is no evidence of problems associated with smaller boats, though that does not mean that such issues have never arisen, simply, that they have not been investigated. Still, why would one take the risk? How many "no big deal"s does it take to sink a boat? Stray arc strikes, undercut, cold-cracking, slag inclusion, etc., where does one draw the line? The thread was started - I believe by Wynand - to assist the first-time builder. My contention was that telling someone to drag a rod across their plate, to get down to flux coating, is not a good idea. I have no nefarious reason for suggesting that this is not an acceptable practice, there is probably no builder/boilermaker/welder/etc., here, whom has not done so at one time or another. Stuff happens, but, should it be considered unimportant?

 

There were a lot of problems with those Liberty Ships. I hesitated to mention them, because the articles I've read seemed more focused on cold-cracking. At the risk of triggering another debate, the issue of cold-cracking is another consideration, especially for the "origami people". Because I have experienced this, I was greatly concerned about 6010/11 being used for the centreline welds , rather than 7018(stop groaning, Tom, lol). My reasoning was that I believed that lo-hi would be an improvement, not that I felt like arguing with people about it. These days, I try to avoid input on discussions in this metal boatbuilding section, because I know that one can not express their opinion if it does not agree with Brent Swain, without entering into an argument. I commented the other day, as the topic involved a point that I had made previously. My life is too busy for more arguments, so I'll wish you all the best of luck & use the forums as a resource centre, rather than for discussion.
Mike

 

Again, most steel boats are being build in backyards, barns etc by amateurs without fancy equipment and who can not tell one steel from another and with no or basic welding skills.

Im a qualified boilermaker, done my apprenticeship in a refinery (SASOL) and worked a few years for them thereafter, spent a lot of time in the power generation game, and all these places immense high pressures are used and it goes without saying that all welds are x-rayed and special welding techniques used. Im not going into numbers and techniques here as we talk about welding small boats.

Then again, most boats are built from mild steel and welded with mild steel electrodes (chain as strong as its weakest link - so why use stronger rods?). A lot is said about E7018 (LH - low hydrogen) series of rods and although this is a common rod for our professionals, it is well outside the scope of many or most amateurs with their buzz boxes. For starters, you need a decent DC welder with at least an OCV of 70 or higher, rods needs to be kept in a hot box etc etc. And if you do not know that rod, it is atemperamental beast and the whole boat will be full of arc strikes if an amateur uses that with his buzz box, let alone weld the hull.

On another tack. I had built a couple of "X rayed" boats, and of all the welds only 10% get X rayed and if that passes, all the welds get passed!
So it comes down to luck in a way if the NDT guys selected by chance the nice welds and missed the bad ones....
Same with arc strikes on a small boat - everytime you put that electrode against the steel, it is an arc. By accidentally "scratch" or pull your electrode over the plate to get going for whatever reason, I for one cannot believe you will have an inferior hull due to that. The plate does not even take up any heat in a scratch arc, and you need some real heat to alter the molecular structure of steel...
and building a steel boat requires many a lug, docks etc to be tack welded to the hull to shape, hold, pull plates or what ever and the hull would then be totally ruined, based on the theory that an arc strike will weaken the plating.

I had built 19 steel hulls up to 20 meters in length and yet to see something going wrong with their arc strike et al.
Going into the world of steam, extreme pressures and fancy steel alloys, yes I agree, arc strikes are a real issue and be taken seriously.

My contribution on this issue to the would be amateur welder is to keep a piece of scrap metal close at hand to strike upon if needed. And to prevent this, it pays one to buy a small Inverter DC welder with a decent OCV of above 60 or so that actually eliminates this problem largely due it ease of arcing an electrode.

 

I for one greatly appreciate this thread. Brent has a chip on his shoulder but I would hope that doesn't keep many of the knowledgeable away. I know it keeps a few out, I recognize them by thier absense. But Brent brings something to the table. He's a sailor who knows how to cobble together a modest vessel and go sailing. That's a good thing but its not the only thing.
I am a skilled craftsman and I admire and respect that in all of the trades. As Wardd put it, pick two.

In a former life I was a carpenter in the ship yards. Some of the very yards where the those Liberty boats were built. A dirty little secret that wasn't really such a secret. One of my fellow carpenters told me his Grandfather was a welder during the war. At times they were working piecework in an effort to build them faster. He claimed the fits were often pretty poor and it was common to fill the gap with rod and then weld over the top of everything. Good enough for government work. Marty said his grandfather felt a little bad as time started to show the defects of some of those Liberty boats.

But I'm a carpenter who has been aquiring metal working tools and I am eager to learn more about metal minutia. It kills me I didn't learn more when I had a thousand guys to teach me. But I picked up more than I knew. Often when you guys talk about something I can see it in my mind from the old days. I hope this thread continues, it's helpful to me.

 

A few moths ago they had a program on DSTV - I think it was the History or National Geographic channel - about the Liberty ships breaking in two. Rivets was the norm then building steel boats and the Liberty boats were to be welded and "modules" built else where joined by welding which was a new technique building steel boats then and to speed up production war the war.

If I remembered correctly about the documentary; when the Liberty ships was breaking in pieces, the found the culprit to be the welds - butt welds. As TollyWally mentioned, gaps, misfit, etc were the order of the day and then they "discovered" overlap of plating and doubler plates. No further mishaps and the Liberty ships went on to win the war so to speak.

 

Friends who worked on the Liberty ships told me that a lot of the welding was downhand with a bare steel rod.
The main reason for building small yachts out of steel is the ability to hit cargo containers at hull speed on a dark night without worries, the fact that welded on deck fittings don't leak, (welding rod being the best bedding compound ever invented) and the fact that you can build a hull ,decks, cabin, cockpit, keel rudder and skeg, and finish detailing and most of the steel work on a 36 footer in three weeks, for a fraction the cost of other materials. Steel is by far the best boatbuilding material yet for offshore cruising boats, by a wide margin.
Having seen so many cruising dreams destroyed by people being sold on the "Be reasonable and do it the hard , time consuming , expensive way" ,yes I get a little pissed off when I see people trying to sucker others out of their cruising dreams.
I think you'd be hard pressed to find any welder, who, in a cramped , uncomfortable position with a sticky rod, wouldn't drag it a few times to get it started. I'd consider those who say they never do, to be ******** artists.
Brent

 

Liberty ships and welding practises

When building the liberty ships the workers were payed by pound of welding wire they "put down".
During construction of the early liberty ships it was common practice to "slug" the welds, slugging is the practice of filling a weld area with electrodes (flux & all) and then welding over the whole thing.
It's speculated that this caused several ships to sink before making it across the Atlantic.

Jarl
http://dallur.com

 

That's what Marty's grandfather said.