Welding a steel hull

Lazeyjack,
Thoughts on your selection:
Those monstrous Millers will certainly do-it-all, but, as you've found, the prices are also monstrous! Most of the shipyards/drydocks/marine repair companies that I work for use Miller Big Blues w/LN-25s. In fact, A lot of guys prefer the portables over the inverters, with the result that, most mornings, there's a bit of a race to the ship/boat/barge being repaired, the slower guys using the inverters. Having said this, there are some nifty, light-weight inverters on the market these days. I do some contract work on the side, for marine repair companies & individual builders. I have two portables for such work; an old Hobart Mega-Arc w/cv interface & Perkins diesel, and a Lincoln Ranger250cc/cv(gas). I use a Lincoln LN-25 suitcase for running wire.

If I were buying the Lincoln again - bought last year - I would step up to the 305Amp version, or go with a Miller of the same calibre, for the benefit of more juice. Obviously, if one is willing to pay the difference, a diesel would last longer before requiring an engine overhaul. What I didn't give a lot of thought to, was the amount of juice required to run a suitable compressor and plasma cutter. I understand that the newer Millers have a generator which is separately run, removing the drag on the welder when performing multiple tasks. I thought I'd mention this, in case you hadn't considered aux. power requirements.

What type of feeder are you planning to use?
Mike

 

Hi Mike
I am now talking the miller300, with Deutz, and s22a feeder, the choices seem many,I just found a true pulling gun that looks like the old hobart linear, slender built to reach into cavitys like keels and with 35foot gun lead
I also found this
http://www.millerwelds.com/products/mig/millermatic_350_350p/
very intersting what you said about the men preferring the grunters
they say the machine in the link will run on one ph. um
well dunno bout that, I know its a departure from the eng driven, but eventually I will have an electric supply
Stu

 

Lazeyjack
The only cobra I have now is one of the old ones and its pretty beat up and very tempermental, I only run steel wire through it, I dont think it would run aluminum anymore. I did have a newer cobra a few years back, dont remember what model it was but it had the circuit board in it and that one welded nice and smooth never had a problem with it. I dont do much aluminum welding just small repairs now and then so I sold it and bought a spoolgun, worked out better for me. For the type of welding your going to do I dont know what would be the better feeder-gun.
Mabee some one else can chime in here and let us know what setup works the best for aluminum?
Tom

 

Oh dear oh dear

look at this welding (birdshit)

i am speechless

falling off my chair

poor *******

http://www.boatdesign.net/forums/showthread.php?t=23939

 

mania, you are way out of your depth here now be a good lad, , break out an 18 gallon keg of beer(firkin) in olde english, free up some steaks and invite me to dinner
Sorry men for degrading our excellent thread
lets talk peining, who peins their plate edges?
as for swain and his all stell pipe masts, christ imagine an inverted yacht!! but hang on ole Swainy, his yachts have angle of vanishing stabilty of 180?
so guess it must be ok

 

who peins their plate edges?
I dont , picked up a small plasma cutter, no need after cutting with it. 16 gage and thinner I use compound hand shear, seems to work the best when you dont have a big shear or room for one.
Manie B
Not sure of your post there
5" sch 80 pipe for mast is a bit questionable. for steel mast larger diamater,lighter wall would make more sense.
Was your comment about it just because of steel mast or you dont like the boat?
Tom

 

Stu,
Those Millermatics are terrific.
Is your choice of wire feeder(s22a) based on price? Are you planning on hanging it from a jib crane? The reason I ask is that a suitcase will take a real beating & continue to perform. The 8RC suitcase is compact & lightweight.
Mike

 

mike I don,t know much abt Miller, I would prefer a suitcase as all by Hobart linears1,and 11, were suitcase, point me to one please
about peining
It matters not whatyou cut with, propane is cooler and faster,
But if you pein say two plate edges that are going into a bulkhead, then the weld will shrink the edges to where they were
If you do not pein, then thats where you will notice buckling\you can pein straight onto the concrete floor or lay a heavy bar under the edge, does not need much, but very worthwhile. you can pein after welding too, in steel, but never al al, and watch the plate flatten out. I know you guys know this,but others may not

 

Plate 4mm and less I always pein the edges where cut either by oxy -acetyne or plasma. But to be fair, you need a lot less pein with the plasma cut due to the "cool" cut.

 

Stu,
The companies I weld for usually have Lincoln LN-25s. While fitting at Vancouver Shipyard this past spring, however, I used a Miller 12RC. The Miller weighs about 10-15lbs less - I think it's about 22lbs, sans spool & whip - and performs well. One great advantage is the digital reading, rather than needle indicator. Another is the size, much less bulky than the LN-25.

I had considered buying a Millermatic for my shop - auto restoration hobby - but they're not as easy to re-sell as portables & suitcases are, in my area. That seems to be another benefit of going with a suitcase/portable set-up, when building.

If you see any old portables laying around, you may want to offer the owner $50 or $100 for it. A buddy of mine bought 2 old Lincolns - not working - for $150 each. He received over $800 each, from the recyclers, for the copper windings. He figures that he can get one decent engine out of the remaining parts. I had no idea my old Hobart harboured such wealth! It had better behave, or else!

Mike

 

Another advantage of origami construction is that shrinkage along the edges of hull plate is an advantage, rather than a problem.. It simply forces more compound curve in the hull plates. I measure an inch to inch and a quarter of outside compound curve in the topsides of a 36 ,betweeen the waterline and the sheer amidships, if the plate has been cut with a torch, less if it has been plasma cut. More longitudinal weld shrinkage there is a similar advantage. This also adds to the stiffness, especially with stringers under it. Shrinkage along the edges does however make decks a bit more awkward to installl ,and a plasma cut along those edges makes things easier, altho there has definitly been no need to peen them in any of the three dozen boats I've built..

 

I use 6 inch OD steel tubing with a 11 guage wall for the masts on my 36 footers. This has a buoyancy equal to it's weight when submerged ,adding to righting moment when capsized. it weighs roughly the same as a fir box section mast common for aboat that size. Test have shown that heavier masts ,to a point, reduce the likelyhood of capsize. Boats capsize a second time far more easily with out the inertia of the mast if they have lost the mast. Many people go for steel for the much greater reliability of steel welding in detailing. They are far less likely to break in a capsize. It comes in 24 foot lengths. The last mast I did , instead of sleeving the joints I went for a 12 inch long scarf. Much lighter, quicker and just as strong.

 

Very interesting, I have never done any peining nor worked with anyone that did, does make sense how it works though. Most my work is form 1/4" to 2" thick buckling is not an issue. Usualy when I work with light gage material if I can get a good clean cut with no warpage I can weld it up without problems, mig with .023" wire, short intermitant welds,cool and change direction of adjoining welds cancels some of the stresses from first welds seems to work allso. I will definantly try out peining next chance I get.
Lazeyjack
I must have gotten confused, thought you were setting up for aluminum?
If not and your looking for a general purpose wire feeder about any will work but like Mike said the suitcase ones are a lot tougher, A lot is going to depend on how you want to set it up, remote cable were you have voltage control at feeder and use contactor in welding machine or acroos the ark model that has internal contactor and voltage sensing clip and to change voltages you have to go back to welder. Options
Tom

 

i was just making conversation TAZ
I used to build in steel) not anymore
for instance if you go to my gallery and look at the nose cone, you will will see how SHRINKING the edges helps, not poss in alloy, you must stretch the middle, , in steel if it was clipper, you would have to Stretch the edges

 

I have used peening to curve heavier longitudinal flatbars in my last boat. It's a good way to take excessive camber out of flatbar deck beams . It allows very fine tuning.
Be carefull using a nibbler on plate for a round bilged boat. It expands the edges , making it go the opposite way you want it to when you pull it around a curve. A friend had major problems with that.