Question For Experienced Steel Boat Builders

I would like to construct a steel cutter outdoors. How feasible is it to MIG weld without shelter? Could it be done when the wind was relatively calm? Could one compensate for a slight breeze by turning up the shielding gas, and if so how might this effect the weld.

Any thoughts or firsthand experiences would be appreciated.

TGoz

 

Not an experienced mig welder mainly stick. But I was confused why the guys using migs outside were using portable shields and I thought it was to prevent people from getting flashes. (ie damage to the eyes). I found out they were portable windbreaks. They were a curved piece of steel that surrounded the handpiece of the welder. I guess working on a steel boat they could be attached with magnets, maybe the magnet that are sometimes used to obtain right angles to adjoining members.
Poida

 

Unless you are in a very windy place you will be ok using MIG outdoors, there will be the odd day when you cannot weld but as Poida says a wind shield works well, The yards here tend to use flux cored MIG wire for external repair and they can weld pretty much in wind as you can with a stick.

Rain is usually more of a problem.

 

Thanks for the info guys.

On the other hand I met a fellow in SE AK who stick welded (outdoors) a 40'+ steel salmon troller. When I went aboard to check it out I thought the boat only a year or two old. It was 10 years. Obviously he built well to a proper design and was on the ball as to maintenance.

He used a gray industrial bridge paint as his primary coating. Inexpensive and very tough stuff.

TGoz

 

If you mig, be careful not to get to carried away, backstep your welds, good luck

 

Good advice. I think, with the event of MIG, many people do get carried away and their "starved horse" boats are the proof.

 

Might I suggest flux core wire if you're concerned about your shield gas blowing away.

 

timgoz.

I’m in the middle of building a steel boat in a backyard with no shelter. as said earlier, rain is more troublesome than the wind. if a gusty day just shield it of with your hand (wearing heavy gloves). if more than gusty im trying to do something else like cutting new pieces and just tacking em’ in. wet steel makes the weld look like foam. if needed you may "dry" the seam first with your grinder. put the disk to the metal very easy and it dries out. but its not very good for corners.

-- Per Larsson

 

Does flux core wire give a slightly inferior weld to one made using traditional MIG with shielding gas? My only welding has been over a decade ago and was stick.

I am aware that I will need a proper amount of practice with any MIG & stick welding eqiupment I intend to use for boat construction.

Thanks for all the above advice.

TGoz

 

I am building a steel boat outside and wished I had a shelter, not because of the rain, not because of the wind, because of the sun. It gets very hot with no shade and makes the work tough. On rainy days there is always something to do in the shop and far enough nice days to weld the boat.

To get back to the wind and wire question I am tacking the boat up with self shielded wire and welding it up with solid wire. The tacks are just to hold everything together, the quality of the beads don't matter as much as it is all going to get cleaned up for the final weld-up. I'm not sure self shielded wire sized to weld up 1/4 in and less plating is approved by ABS standards , I don't think it has a V-notch rating but its tensile and yield strength are way over the strength of the raw material. But all that doesn't mean anything if the welds aren't perfect and that's what really is important. As far as I know a lot of custom boats are welded with self shielded wire, but I personally don't like it.
I have a few issues with it.
First: As you weld you skip around so continuously start and stop beads. My experience with self shielded wire is that it has that tendency to make a tip of flux ( or whatever high resistance stuff it is) on the end of the wire when you stop a bead and have to constantly cut off the end, it's a drag.
Second: The flux in the wire leaves a white powdery crust on the weld, that stuff doesn't brush that easily. As the beads are intermittent there are those points were the welds will join to each other, if the flux is not perfectly cleaned off the weld already down, you risk to get some pin holes were the beads ride each other. The same problem happens when you are going to weld the other side of the plate as the base of the welds are also coated with flux, it all has to be cleaned up. Just like the stick flux. The key for a sound weld is always cleanliness.
Third: It stinks.

Other than that it runs nicely, makes fairly nice beads (when run properly), not to much spatter and is easy to use.

I have considered using a dualshield wire but ended up preferring solid wire run with 75/25 argon co2 mix. I can weld with a very light breeze but do put up my gas a bit compared to when I weld inside, I rather that than having to redo a weld. A shelter is still the best way to go. On breezy day I can guaranty that by the time you got some shielding organized the wind will have clocked around.

Cheers
Murielle

 

Thanks for the detailed info M&M.

Yes, Murphy's Law would definetly dictate the inconvienient wind shift.

When you take into consideration the cost of the gas for solid core welding, how much more expensive is the flux-core wire to weld with?

The hot sun would be a big pain for me as I am highly intolerant to heat & unfortunately at this time I am way down here in SW Pennsylvania.

M&M, are you building the hull upright or upside down? She must be a substantially sized boat if you are using 1/4" plate.

TGoz

 

Well, It seems like it is all expensive no matter how you count and is not that easy to compare as you don't only want to consider the cost of wire and gas but also deposit rate and efficiency, which also depends on the size wire you pick and your settings.

I buy my Dualshield flux core (with gas)71T1 0.045 wire $2.95cnd / lbs. Run between 140 and 190 amps the deposition efficiency is around 78/79%.
The self shielded flux core (no gas) 71T11 0.045 wire $3.9 cnd / lbs. The efficiency is equivalent as the dualshield. The 0.045 wire would not be run hot enough for steel under 3/16 ( at lower amps you lose efficiency and get more spatter). The 0.035 wire would be better and easier to handle for thinner steel but the price per lbs is a little higher.
The solid wire 0.035 70S6 $2.12cnd / lbs. In short arc and run with 75/25 mix the solid wire efficiency is in the order of the high 90's, about 98%. I would stay away from strait co2 if your welding machine can put out sufficient heat as the savings in gas is not worth the spatter and loss of efficiency. With the mix you will get no spatter at all (if your steel is clean).
As I switch wire around depending what I'm welding, farm equipment or boat, I don't have a good track of my gas cost. It seems to all be equivalent in cost on a non industrial scale.
The real way to save on your welding is to have a good sound weld the first time, it might be pricey but it's the rework that is expensive. Those grinding wheels can add up very quickly.
Now, by all means, I am no expert, I'm just talking from my experience, research and reading.

About the heat, I thought I was tough and fairly tolerant but once I got all the gear on that sun is brutal.

My boat is a heavy displacement 50ft boat. Only the bottom plate is ¼ in but it is pretty heavily built.
Pics of the construction http://www.magma.ca/~ovenden/

Murielle

 

Murielle

It is often poorly understood with MIG that you can vary the weld significantly with the shield gas mix. The higher Argon mixes produce a very flat weld but good penetration without a wide V and multi-run can be hard to achieve with thicker sections.

Have you ever tried 100% CO2 ? It produces a hotter much deeper penetrating weld, spatters a bit but has some very usefull characteristics when welding thicker sections with a full weld join. The CO2 is so much cheaper. I found it used a lot in New Zealand for steel boat building.

Good luck with the project

 

I like the design. What an ambitious project. It looks as if things are really progressing well! Are your topsides 3/16" (approx. 5mm) plate?

The boat I have plans & some material for is a 28' utilizing 1/8" topsides. I understand this is at the lower limit of practical thickness. That is one reason for my interest in learning more about MIG, as they say it, if used correctly, will not cause as much heat distortion as stick.

As a machinist I work around alot of welders daily but they are mainly involved in multipass heavy welds with petro-chem fittings.

Liked the photographic composition & progression of your website.

TGoz

 

I think I ,ve seen quite a few posts here, but I do not remember seeing much post on the old skills of boilermaking and boatbuilding And this is because more and more boats are amateur built either by engineering fab shops or anyone who just says"I'll build a boat.
In Aust a "boilermaker " is anyone who fabricates, even if they have no idea of actual boilkermaking, a true misnomer
Someone said, "starved horse look"
Dont forget, to peen your joints, ESPECIALLY joining flat sections like B/H,s
or in fact shell plating edges peening is just taking a hammer and dolly , the dolly can be the concrete floor of best a piece of heavy flat bar, run along the edge with a heavy hammer, not a sledge!! and then when weld time comes, the plate will be under less stress, distortion held Do not forget to backstep