welding on a steel yacht hull

Hello Tug
Mike is welder/fitter from a few post back
As far as building a 40' tug using a 90 amp FC welder,doutfull 110 volt machine at 20% duty cycle at best, Even if you could manage to get saticfactory welds it would be short lived
Tom

 

Taz--yea--I figured it wouldnt be the way to go--so i have a 225 amp arc welder for the job...i think that shoul dbe good--ill use 6010 or 7018 or 6013 rods...
how do i figure out how much weldment will be needed on a 40 ft'er?

 

tugboat,
I suppose it depends on what you're most comfortable with & what thickness of plate you'll be using. As I'm sure you can appreciate, wire is faster than stick, hence the heavy use in the shipyards, these days. With wire, the duty cycle of your machine becomes even more important than with stick. For industrial purposes, any stick(SMAW) machine that does 65% duty cycle, or better, is fine, but because one makes longer runs with wire(FCAW/GMAW), most industrial machines are hitting on 100%.

Welding bulkheads on a ship, 3/16" plate, we'll run 28 to 32 amps, for the average welder, with FCAW-CO2shielding(CV), which puts us around 200 to 250 amps. I prefer a resultant 170 to 180 amps on verticals, but I could be on deck 6 & my machine on the drydock deck, so I can't be running up & down to adjust.

For stick considerations, I recommend lo-hy(7018), unless you're welding real crap steel, then 6010/11. DCRP works best. Are you familiar with the B.C. Ferries? Between 2004 & 2008 we refitted 5 of them & built a new one(MV"Island Sky"). On one, we filled in the "window" cut-outs on the car deck. This was during the winter and, on a Friday, a few welder/fitter teams tacked the inserts in, so production welders could weld them up on Monday morning. Come Monday morning, our chargehand was foaming at the mouth because all of the inserts had broken tacks - two inserts fell out - except for mine & my partner's. By a shear fluke, I'd had 7018 in my pouch & used those, whereas, the others had used 6011. We've had a lot of discussion, here and elsewhere, but I can only tell you what I observed &, noting that you're in an even colder climate, suggest you give some consideration to it. Personally, I wouldn't use 6013 for boatbuilding.
Mike

P.S. Looking forward to knowing what you're building.

Correction: I thought I typed 3/16"+ plate.

 

Hi, Good advice welder/fitter. A 40ft Tug ! good size project a little 90 amp Mig will be struggling . Dead right on the 7018 , we use nothing else for jobs like this.

 

Yeah, I'd imagine "tugboat" will be using some relatively thick steel in certain areas, depending on whether this is a "push" or "pull" tug, dual purpose, or a yacht that looks like a tug. Regardless, 90 amp Mig won't cut the mustard.

 

Hey Guys- thanks for the responses - very helpful...yeah i have to weld up some thick members for the keel. 1 inch thick by 6 inches. I was thinking of using a high deposit stick like the 7018. The boat is actually not for commercial use but i suppsoe i wuld build it close to scantlings listed.
i did get rid of the 140 amp 115 volt mig in exchange for a stick ac 225.

I guess the stick will be slower--will it cost more for weldment too??...ive done small jobs beofre--i welded up a pair of steel pontoons. but I used flux core for that. so my arc skills need some honing.

 

Hi Mike, I must have mixed up you for another mike on here. sorry for any mix-ups.
I dont have a dc machine--i know they run better beads-but i also understand that with practice you can run good beads with an AC arc welder too?? Ill use the 7018's i had read this is a high deposit stick with great penetration. just what the doctor ordered for a boat. so ill put my time in with those. weld up some small projects like tables and an a-frame lift before I start the boat. do you need to keep the 7018's warmed up before using them?

 

I know this is an elementary question but -what would be the difference between a 40 ft'er and a 25 ft tug be in regards to weld time and weldment costs? Also i still looking into fer-a-lite for a material. steel is ideal , but what used to be bargain material it seems now is the most expensive way of doing a boat next to fiberglass...

I figure that I could go for a 220 volt flux core...it has about 20% duty cycle at 105 amps.. anything else --well..they are pro machines and i just don't want to outlay 2000.00 for a welder when i can go with arc. I know many will say that in the end it will balance out...but for me n real world scenerios, my build site-etc it makes sense to go with a simple ac 220 welder...I did doubt that a 140 amp flux core (rated for welding 5/16ths in a single pass) could build a substantial heavy displacement vessel- my thinking was that arc would be the only viable way for welding the heavy keel stem and other areas. as well as getting the thicker welds needed for plating.

 

Thanks NZ_Shipwirght--Ill definitely take that under advisement..much appreciated...it confirms what i thought would be used for a substantial steel boat ...cheers!
p.s. My brother is a teacher and spent two years in NZ...Id love to go there some day...

 

Tug
the cost and labor difference would be huge between a 25 and 40 footer. If time money and space are a key factor go smaller. As far as welding with stick using a 225 AC buss box welder, no problem there. They do make a 7018 to run on AC, I cant tell you how good it is I have not tried it, my machines are DC. 6011 will work fine with that ac welder.
Tom

 

If I had to choose between a lightweight flux core wire welder and a reasonably heavy duty stick welder, I'd use the stick welder. The keel shoe of my Witch is 200 x 40 flat bar and I did all the welds including double V butts using a stick welder, E4111 rods for the root run and E7022 (or 7024, I forget right now) to fill.

PDW

 

tugboat,
Tom & Peter have already answered some of your queries, so no sense in repeating, other than to agree with Tom that building a 40 footer will take significantly longer & cost significantly more than a 25 footer(probably x2+).

Yes, with 7018 you do need a rod oven. As long as the package you buy them in is properly sealed, you can use them for 4 hours before they need to go into an oven. To be honest, I and others have gone way past this time-line, but it's not good practice. You can buy portable rod ovens or make your own. If you're close to the border you could go get a Keen oven for a decent price. http://rodovens.com/

Otherwise, you can pick-up a used oven, use an old toaster oven, etc. . The main point is that it must be able to store your rods at 250F or more. If lo-hy rods get wet, you have to bake them at 600-800F. make sure you have them on a metal tray, not a rack, & roll them every once in a while.


Welding with 7018 is easy enough. I'd suggest 1/8" rods@ 120A, a bit cooler when out of position. For flat position use circles or slight weave, for horizontal use crescents & stop briefly at top, verticals are side to side weave, overhead are drag, small weave if needed. Try to keep close to 90degrees. Don't be afraid to use two hands, you can steady your rod with your free hand and, though you'll go through gloves a bit quicker, lay in beautiful welds. It also makes striking your arc easier. One common mistake for new or rusty stick welders is moving too fast. Remember that 7018 is not a vertical-down rod. keep tight arc. It's faster than 6011 - iron powder & results in more ductile weld. Fast-fill rod.

If 6011, keep your whips short, come back almost to same point(don't make fish scales=weak bead). Great for very rusty steel, deep penetrating. fast-freeze rod.

As far as using an AC machine, you'll still get reasonable penetration & you'll avoid arc blow.

So, what type of tug are you building? Will it actually operate as a tug, or is it the style you want for a recreational boat?

Added: With 1/8" 7018, in flat, horiz., OH positions you can run up to 150-160a after a bit of practice, which makes for pretty fast stick welding. Non-structural flat position welds can be done with 7024, very quickly.

 

That's what I used. 3.2mm E7024 rods, 160A indicated, the slag just lifts up as it cools on the bead. Lovely beads over the top of E6011 root runs. The E7024 rods are nowhere near as fussy WRT moisture as E7018 rods either IIRC. I've never used those and I probably never will.

Tug, if I was short of money I'd use the 225A AC welder and not worry about a MIG until I had the money to burn. Honestly the AC welder is all you need to do the job. I can get full penetration welds on 4mm plate using 2.5mm rods in all positions welding from both sides, with a proper edge preparation. As you'd be using thicker plate, you need worry even less about distortion (within reason).

PDW

 

I still don´t get your reason behind the "thoughts". If we let the FAL out because it is the most labour intense and weakest, Steel should be your first choice anyway.
You know already how to weld, but as it seems, you have not built in other materials.
Tug designs, as close to working boats as those you have in mind, require weight and strength. Both is provided in a cheap and sensible combination by steel only. Building lighter and ballasting is not very clever here, this is not a sailboat.

Cold moulded (wood epoxy) is the most expensive btw. Followed by carbon FRP, classical wooden building, strip planking, and then, at the lower end we have steel. Glass / poly is the cheapest when you have a mould, and the second cheapest, (after strip plank) if not. S&G can be a cheap way too, but is not always. FC, as you know, does not exist, hence I did not mention it.

A 40ft design of similar purpose, will be at least 2 times the cost of a 25ft boat.

Richard

 

Sorry for taking so long to respond welder fitter-

Im going with the smaller design--25 ft a mal low design--it simplifies my life--i dotn have to rescale or guess..or try to design soemthing and yes im building her in steel--

im not even going to stretch her to 28. Its intended use is crossover tug using it to push a houseboat barge. I plan on doing some light commercial work although i am going to get lynched for this but i wont be getting it classifed and registered. Ill do some under the table work moving boats off sandbars or rocks etc. maybe doing some small vessel assists under the table...the fine is only something like 250.00 -and its only illegal if you get caught..ok bad attitude i know--ill see what happens when the boats built..that reminds me--i have to go check up on what scantlings it needs to be built for TC. guidelines.

one advantage of the smaller vessel is that it can do work in small places like canals and move around in places 45 ft'ers cant- such as marina's and what have you. cost is a consideration for any owner and its both economical to build and moor and takes less time- the old adage- better a finished 25 ft boat in the water than a unfinshed 40 ft'er on land... and to be frank ive gone in circles for a while on the design because i didnt want to let go of this one design i really loved. the st class. but the reality of it is its too big for my needs..and i am letting it go--so--its done. ive made my decision...
In fact reading about what people in the last few posts said about the difference in costs- well that gave me the push I needed...
also
I can't thank you enough for all that great wisdom...ill be re-reading these posts everyday as i practice for the job. Ill do a lot of practice before i start the boat. And your tips are extremely helpful Mike. where are you based in Bc? My brother in law is first mate on the Princendam of Holland america lines. he was a port authority for a while a couple years ago, an safety inspector at the port of vancouver.

anyway -ok ill find a rod oven--you mentioned an old toaster oven could work??..it seems cheap of me to go that route but im all about seeing how little i can get away with in costs.
much appreciated--without a doubt the most helpful thread posts ive ever read are right here.