Minimum MIG amps for a 10mm mild steel plate? Narrowboat overplating

[arther dailey]

As Matt said, stick is the way to go if you're outside, way cheaper too.
Might be worth looking at the power supply, I ended up with about 50m of extension leads running a brilliant little inverter stick machine. My previous mig an old transformer machine couldn't cope & most of what I did was 4 - 6mm with occasional 8.
I'd been reluctant to go stick as previous experience with an old buzz box had not been great but the inverter made the whole thing a pleasure.

what breed/size inverter probably ould be usefull to the op

 

[Morrisman]

You may need lots of power to weld 10mm, but what thickness are you welding to, and what condition is it in? If it's old and rusted away you could well end up blowing holes in it left right and centre.

 

[TEO]

what breed/size inverter probably ould be usefull to the op

Good question but I'm not sure -depends a bit on whether he has to stay with the 10mm. Does seem v. thick for over plating.
Don't think mine's available anymore (thermal arc 175te) but reckon that any of the usual brands at 200a should do.... Unless it's 10mm then I don't know - on the few occasions that I had to weld thicker stuff on the boat - 15mm cleats to 4 & 6mm plate I just chamfered the 15 down to virtually nothing, used the biggest rods I could run - 4mm - and made several passes to fill the v.
12yrs & much rope on cleat action later & every things still doing the job & they get a pretty hard life

 

[Morrisman]

If the whole bottom of the hull needs another layer adding you're talking over 2000kg of steel. Which will drop your boat a good couple of inches lower in the water.

 

[Munkul]

4mm 7018 vac pack rods and a 180 amp inverter stick welder (160 might do) would be my go-to... that or become very good at welding uphill/overhead with mig...
Even better, some dualshield fluxcore, but you'll need to have a welder that can run 220 amps at a good duty cycle still.

 

[fizzy]

If the whole bottom of the hull needs another layer adding you're talking over 2000kg of steel. Which will drop your boat a good couple of inches lower in the water.

Depends on the size. Boats have surprisingly good payloads.

 

[Morrisman]

Depends on the size. Boats have surprisingly good payloads.

Just a rough guesstimate, but steel is approx 10x the weight of water, so adding 10mm of steel across the whole of the footprint of the boat, the hull would need to displace an extra 10cm depth of water to balance it out. I think.....

 

[julianthegypsy]

Depends on the size. Boats have surprisingly good payloads.

I have known it to be an issue. You would definitely want to remove some ballast...

 

[Pigeon_Droppings2]

I know nothing about boats...but I would have thought they'd simply survey the current thickness and then over plate to make it back up to the original spec or some pre defined over spec (or there abouts)?

But my entire knowledge of canal boats can fit comfortably in an ants lunch box...with plenty of room for an apple!

What I do know (owning one) is the Kemppi evo 200 will struggle with 10mm plate without pre prep.

 

[addjunkie]

Just a rough guesstimate, but steel is approx 10x the weight of water, so adding 10mm of steel across the whole of the footprint of the boat, the hull would need to displace an extra 10cm depth of water to balance it out. I think.....

Not sure on your maths but the logic is correct. The extra tons, would also alter the stability, depending where the weight is added. Also increasing the draft may have an impact on how many shoppin* trooley you hit in the canal and how much silt you bring through the engine cooling water.
Realistically I cant see the full thing needing over plating.

 

[Brad93]

6mm rods on 10mm plate?

You could get away with a lower amp welder by doing some preheating & multipass runs but 10mm takes a lot of heating so the more amps the better.

Simplest way would be a Pickhill Giant 220a oil cooled welder & 5 or 6mm rods, probably what was used to build it originally.

I'd be concerned about everything warping using those sort of amps.

You're figures are wayyyy off.

10mm plate you need no more than a 4.0mm rod.

you won't even burn a 6mm rod at 220A.

Not only that, i haven't seen a 6mm rod in years. Last time i did they would of been Fastex or Armoid by Murex.

Bear in mind a 4mm 7018 rod will just about run at 150A. Realistically you're gonna be at 160-170A.

5mm rod is 180-230A. Already in excess of your quoted 220A and tripping the breaker or thermal cutout.

6mm rods take a good 230A+ to light and run effectively.

Attached data sheet for fastex - 7024 down hand electrode commonly used to build boats. Known as a jet rod, takes even higher amperage to run properly.

5.0mm rod takes 220A minimum.

 

[Pigeon_Droppings2]

I googled it....

Narrowboat surveys explained

Guide to repair and maintenance work needed for Canal and Narrow Boat Hulls, with information on required survey work and the processes and procedures undertaken.

www.whiltonmarina.co.uk

I hadn't appreciated that the plate would be welded at the sides along a nice clean lip?...reckon that would be nice to do with a stick welder. Also there is mention of holes cut in the plates to weld to the existing bottom plate and "V" gapped joins to do between repair plates...thats probably where a mig would be a lot easier (overhead)...but the plates would be "V" gapped so butt welded?

Just trying to understand the process as it sounds interesting.

 

[Turbo]

You're figures are wayyyy off.

10mm plate you need no more than a 4.0mm rod.

you won't even burn a 6mm rod at 220A.

Not only that, i haven't seen a 6mm rod in years. Last time i did they would of been Fastex or Armoid by Murex.

Bear in mind a 4mm 7018 rod will just about run at 150A. Realistically you're gonna be at 160-170A.

5mm rod is 180-230A. Already in excess of your quoted 220A and tripping the breaker or thermal cutout.

6mm rods take a good 230A+ to light and run effectively.

Attached data sheet for fastex - 7024 down hand electrode commonly used to build boats. Known as a jet rod, takes even higher amperage to run properly.

5.0mm rod takes 220A minimum.

View attachment 392877

I will admit I got mixed up in my rod sizes. I was recently welding some heavy steel plate in what I thought were 5mm rods when in fact they were 4mm.

They were 4mm 7016 rods & they ran very nicely at 170 amps.

 

[Brad93]

The minimum MIG welding amperage required for welding a 10mm mild steel plate depends on various factors, such as the type of MIG welding machine, the electrode diameter, and the welding position, among others. Generally, for welding a 10mm mild steel plate using MIG welding, a minimum welding amperage of 180-200 amps can be used as a starting point. and I have some information about reaction time test .

180A won't touch 10mm plate

 

[bert]

The Hull on my boat only has steel thicker than 10mm on the bottom of the keels. Everything else is 5mm thick.

Not a canal boat though.

When I replaced some of the starboard keel I cut it all out and replaced with new. Overplating is a bodge really.

 

[Erie Fred]

I’m no boat expert but 10mm does seem awfully thick for overplating.

Ice breaker duty... "Ramming speed sir"
Or is that "Ludacris Speed" ?

 

[addjunkie]

Ice breaker duty... "Ramming speed sir"
Or is that "Ludacris Speed" ?

Having broken ice in a big boaty thing, last thing you want is to hit it hard and fast…..tends yo put holes in them 10 mil plate or not!

 

[henry Kadzielski]

I would like to add my two cents worth. I hate stick, plane and simple, not good at it, but can manage if absolutely required. So if I can do the job with a mig that's the way I would do it. Down side of the mig, the metal must be clean. You can get away with some crap with rods but solid wire, the base metal MUST BE CLEAN. Depending on how much you have to do, can you weld 10mm with a 200amp machine, well yes however you may be maxed out and you will need to do a three pass run. When I did my mig ticket we welded 10mm samples with .9mm solid wire at about 180'ish amps. Currently I am using .8mm solid wire and can weld up to about 6mm in one pass but that is about 210amps. With the solid wire the weld pool is just that little bit easier to see, the weld done properly is cleaner and out of position is just that bit easier. Duty cycle will be your first problem, followed by the mig gun getting too hot resulting in feed issues. Small mig welders don't come fitted with good guns and finally has anyone shown you how to do a 3 run fillet, are you proficient? Multi run welds are not difficult, but there is technique involved. Once you have that down pat there is pretty much nothing that you can't weld.
Hope it all goes well

 

[KemppiFrog]

Stick my oar in here .. Just welded some bits up to make a centre plate for a friend's boat. 10mm, BUT, I could go at it from both sides, so a single run with 8mm wire in a V'ed joint did it OK. Welder is a transformer Mig 280 amp, but not near the top end. (Prob pop my supply..)
The idea that 10mm is needed to overplate boggles me a bit.. 5mm would do it for your life expectancy, not to mention trying to get it round the bends at the fore and aft bits...
Average 40ft steel yacht is built out of 5mm for the hull and 4mm for deck and cabin. And that is to allow for a bit of rust reducing the thickness.

Done some work an a local friend's Dutch steel residential barge (not welding) and at 80x20 ft it has a hull of 6mm . Slightly different from a narrow boat, more like a penthouse apartment, very comfortable, but with 2X 120 hp engines and a 65 hp bow thruster (!) with a 360° thrust nozzle. Quite enough to move it around the Marina without bothering the main engines.

 

[8ob]

I have known it to be an issue. You would definitely want to remove some ballast...

Woman overboard, sorted

Bob