Aluminum boat - Cracked welds

[crackedglass]

I picked up an older Duranautic 14' boat this weekend, got it cheap, but it needs some work. The rear bench seat has a panel beneath it which is welded in 6 places to a strip which is riveted to the hull. The upper two welds on each side are broke free. They attach what appears to be 1/4" aluminum angle to a sheet metal panel which I think is there to provide some support for the hull. In the water, the weld has no real effect but on the trailer, pulling on the sides of the boat will separate the weld. The hull is rated at 40hp, and I intend to hang just that on it, so it needs to be perfect. Does anyone have any suggestions as to rewelding these points?
The hull has no ribs, these are built flat, the seats and the lower strakes give these all their strength. I have a mig welder with a spool gun but am leary about welding sheetmetal this way. The factory has short 1.5" long welds in about 6 places along the bottom of the hull. The boat has been in use constantly, most likely with these welds cracked for many years but I like to make this as rigid as possible since I intend to up the hp from the current 25hp to it's max of 40hp this spring.

 

[techjob4u]

Re: Aluminum boat - Cracked welds

I am new to boating restore so not sure if I have the best solution. Mig tig weld would be best but if the sheet metal is think you might burn thru.

I bought some alumiweld or Alumaloy sticks on ebay. Just do a search under both you will find some who sells them. You use a braising torch and they melt and weld all types of aluminum together.

Its a little tricky to get use to using. I have not used it on my boat but I used it to repair my mail box after one of the kids mothers in cub scouts backed into my mail box and broke the connecting pole which supported all of the weight of the sign with address, mail box and assembly off one small dimple that attached to the pole in the ground. After using JB Weld and it failing I was surprised that the welding sticks worked.

Below is a link to a seller but you can find them at home depo as well just for 4 times more the price!

http://cgi.ebay.com/ALUMALOY-Alumin...emQQptZLH_DefaultDomain_0?hash=item3a559f0fa4

 

[Bob_VT]

Re: Aluminum boat - Cracked welds

Hey a spoolgun is the way to go. About 75% of us tin owner's would kill to have access to one

Take a few photos of the area. If I read the post right you are welding brackets and not the hull itself.

 

[crackedglass]

Re: Aluminum boat - Cracked welds

Hey a spoolgun is the way to go. About 75% of us tin owner's would kill to have access to one

Take a few photos of the area. If I read the post right you are welding brackets and not the hull itself.

I'll get a few pics once the snow melts, it's under about 2' of snow right now.

There is a channel or track which is attached to the inner hull, it's riveted to the hull. The seat panel which goes between the bottom of the bench seat, (which is foam filled), and this rail. The panel is welded to both the bottom of the seat's front panel, and to this rail on the hull itself. Two of the upper most welds on the hull side connecting this panel to the channel are what is cracked. Welding this will be very close to the hull itself, and right next to the back side of two rivets holding this channel in place. The channel is riveted through the lower strakes of the hull from the outside, there are no rivets which hold only this channel in place, all go through three layers of material.

My concern isn't melting the hull but damaging the rivets or their seal. I considered just standing the hull up against a tree and welding this with alumaweld sticks but there's little room for error. I have a spool gun for my mig welder but it's lowest setting is way too hot for light metal like this. I did a few test welds on some similar gauge metal and the first arc burns right through. It does fine on heavier metal but not on thin aluminum.

I am also concerned about warping the outer skin of the hull, with those alumaweld sticks you have to get the metal pretty hot to make them stick, nearly to the point of melting itself. I've also had those welds crack while cooling when welding large items like boat hulls.

 

[Kevin Morin]

Re: Aluminum boat - Cracked welds

crackedglass,

I probably didn't get the best idea of where your weld failures were located but I can make a few remarks which I hope are some help?

Don't try to use aluminum coated electrodes for anything that 'matters' since they produce such a poor weld -it is a safe statement to say they're not worth their time anywhere on a boat.

Next MIG would 'have to' be done with a pretty capable power supply, one that can produce globular transfer or pulse or pulse-on-pulse to manage the fusion AND total weld wattage. Otherwise, as you've noted, burn through is uncontrollable and you're farther behind than when you started.

TIG is a good candidate for this weld if you can get position to weld, again, as you mentioned, standing the hull upright or working inverted with the skiff on horses. This last may sound hard core but a TIG bead along the hull surface plane -inverted- is just an overhead horizontal weld that would give good room for rod and torch access and elbow clearance while standing under the inverted skiff. Visibility is often the biggest obstacle on welds like you've described.

If your MIG power supply doesn't have arc controls like 'pinch' or 'pulse' (s) 'softstart'; 'run-in' then the open circuit voltage may be fixed -that means when you light up the potential on the filler wire is fixed and high enough to light larger wires. If you can't tune this down, you'll get some headaches initiating the weld on the thin material- so you can use a run-on block next to the weld to get 'lit' and then travel off the heavy [1/8" or 3/16"] block onto the thin stock when the weld drops from open circuit voltage down to weld voltage. I'm not saying the machine will keep even small wire 'lit' at low voltages but this may help.

I'd say that you need 0.030" wire - or smaller, 0.025" might work- and you should be running 5356 alloy wire but not knowing the alloys of the boat you may find 4043 easier to run? I personally won't run 4043 on anything except cast- but some folks do use it and it will run much easier than 5356 on the 5000 alloys- but the welds are notoriously weak by comparison to the 5356.

There's no use discussing voltage settings since your machine's slope ratios aren't known, but if you were able to get very small diameter wire then adjust the machine down until that wire will 'stay lit' on thinner stock- you may be able to get this weld done with the equipment on hand?

good luck and

Cheers,
Kevin Morin

 

[crackedglass]

Re: Aluminum boat - Cracked welds

I have two mig welders, one is a Lincoln SP200, the other a Millermatic 200 with the spool gun option. There are no adjustments on the welder other than heat and speed. The spool gun kit added a toggle switch and it plugs directly into the machine. I was told by a local welding supply here that they're ok for rough work but forget it if you need to do something really thin. This boat isn't really thin, but it's a lot thinner than anything else I've welded on with it. The SP200 is a much nicer welder but I have no spool gun for it. Buying one would mean adapting one from a newer model and about $700. If I'm going to spend $700, I might as well buy the right tool for the job.
But again, I had two welding supply salesmen tell me that I need a huge water cooled machine to do thin aluminum like boat hulls. I was told that the mid sized machines, basically those in the $1500 to $2500 range are best on heavier aluminum, and that I'd need to spend well over $5k for one to weld aluminum sheetmetal.

I have some experience tig welding, but that was welding castings and heavy extruded aluminum using an older Miller machine with a liquid cooled torch. I've never touched anything thin.
I welded up some brackets on an aluminum flat bed with my Miller 200's spool gun once, it worked ok but it was tough to keep a decent looking weld going.
It also took a lot of heat. I have .030" wire in that spool gun.
I deal a lot with aluminum boats, as well with outboards, I'd love to have a machine that will do both hull repair and fix things like skegs and fins on outboards. I've used those aluminum brazing sticks with varied degrees of success. They work well on clean, shiny aluminum, I'm not sure how well they will weld 30 year old aluminum that's been exposed to salt for three decades the metal isn't pitted or corroded, but it is gray in color.


The area to be welded is not directly on the outer hull skin. Picture a 4 bench seat type aluminum boat, the front and rear seats have bulkhead walls beneath those benches, these panels are welded to two small opposing angle strips which are attached via the same rivets that hold the outer strakes on. The two end welds are broken. This allows the hull to spread or widen there. It don't move in the water but the welds separate when sitting on the trailer bunks. My guess is that they fatigued from the weight of the motor flexing the hull while in tow. The same bulk head panel also makes up the front of the bench seat, so in effect, the rear most bench seat is also missing two welds. It's still held in place buy 6 other upper welds in the middle and rear of the seat, but the front is unsupported.

I called around here trying to find a welding shop proficient with aluminum hulls like this but all refused to touch boats. To make it as good as new, it only needs two 1" long beads rewelded. If I knew I could get the brazing rods to stick, I'd use them, but there's also the fact that the seats contain poured foam, and the heat needed to preheat the area with a torch would no doubt melt or set the foam on fire. A tig or mig would get in and get out much faster. The area to be welded is about 7" from the nearest foam and that panel doesn't directly contact the foam. The heat would transfer first to the hull then the seat itself.

If I get home during daylight one evening, I'll shoot a few pics of the cracked welds and the area in general.

 

[crackedglass]

Re: Aluminum boat - Cracked welds

Got home in time to shoot a few pics of the cracked welds, after putting some light under the rear bench seat, I can also see a few cracks in the angle which it's welded to. These are the only through hull rivets on the boat below the water line.
They most likely came from the ill supported roller trailer it was on which held the boat too far out on each side, these welds correspond with a roller on each side. The Starboard side even has a minor dent there which explains the cracks. The outer skin isn't touched and the boat doesn't leak a drop.
I even considered binding the hull in place to force the panel back into place, then drilling as few holes through both the angle and bulkhead panel to make a more secure connection but the right answer is a good weld job. Each seat has one of these beneath it, I was mistaken when I said they connected to the seat, they stop about an inch below the seat. They appear to be both for support and to act as a bulkhead in case of a leak too I guess.

Here's some pics of the welds that are cracked.

Starboard Front:
http://i50.tinypic.com/sbngyf.jpg


Starboard Rear:
http://i47.tinypic.com/9ad7oi.jpg


Port Side Front:
http://i47.tinypic.com/2v9rb6e.jpg


Port Side Rear:
http://i47.tinypic.com/dc4ow4.jpg

 

[Kevin Morin]

Re: Aluminum boat - Cracked welds

crackedglass,
sorry not to reply sooner, I didn't see the posts.

I'll give some opinions about welding power supplies first.

Castings like outboard lower unit skegs, or props or even bow and stern corner castings of some skiffs can only be welded with full control and full strength using TIG. I won't address brazing or stick electrodes or gas welding because all of those methods are a far distant second best, in my experience.

Aluminum TIG has to be done AC and most multi-method welders that offer TIG and MIG in one cabinet are only providing DC TIG with a MIG and stick power supply- this means you'd almost always end up with two power supplies for aluminum work- one MIG and one TIG.

Generally, wire size and weld wattage are directly related to aluminum MIG effectiveness. In all cases of aluminum MIG the weld is accomplished by attaining the heat of fusion (melting) the top surface [at least] of the parent metal and applying sprayed or shorting arc molten filler. Since aluminum moves heat about 7 times faster than steel we can generally say aluminum MIG is about 7 times as critical in adjusting the set of weld variables.

Travel speed, angle of torch/arc to the weld, rate of wire feed and voltage settings as well as wire size are all much more critical to a consistent aluminum MIG weld compared to the same weld in steel MIG.

You don't need a huge water cooled power supply of 350 amps and 40 volts welding power to weld 0.080" or 0.060" aluminum sheet! But you do need that range of power supply to weld single pass 3/8" or 1/2" in the keel of a welded boat 30' long. So making any statement about what power supply is needed has to be coupled with the use for that power supply.

Wire size ranges from 0.025" to 1/16" where; 0.025" and 0.30" dia. will weld from 0.040" up to 0.100" fairly well and; 0.035" dia. will weld from 0.100" up to 0.160" (5/32") maybe 0.187 (3/16") if your shop is warm when you begin? ).045" and larger diameter wires are for materials 0.125" and heavier but more common beginning at 0.187" and up.

For thinner hulls and light extrusions you'd use a 200 -250 Amp power supply and 0.025 to 0.035 wire but there are 'catches' to these rules of thumb.

Small power supplies have less arc controls compared to the large capacity machines- so welding thin materials with a 350 amp machine can be considerably easier than a 200 amp power supply. Here's why; the larger machine has pulse or pulse with pulse mode arc controls that allow a MIG weld on very thin material to be controlled at slower travel speeds. With conventional spool guns and inexpensive lower amperage machines the required travel speed of the weld is almost beyond human ability.

So, this may be why your welding supplier suggested a large capacity machine - that model may have had the more extensive arc control features allowing MIG bead to be sustained on very thin material at 'normal' welding speeds?

One older model power supply that may help weld thin and stay cost effective is the PowCon 300 MIG. This power supply, often available on eBay for a few hundred dollars was available at one time with a 'pulser box' that would create a pulsed MIG bead and allow thinner material to fuse while keeping the overall heat of the weld down to manageable travel speeds.

I had several of these machines for many years and they were reliable and dependable, but most our work was 0.125" or heavier.

more to follow

Cheers,
Kevin Morin

 

[Kevin Morin]

Re: Aluminum boat - Cracked welds

crackedglass,

As to the welds you show here, I'd don't think I'd weld these repairs. The reason is that the orginal welds look like they tore out the parent metal of the vertical extrusion rolled to rivet into the turn of the bigle?

One or two welds, so poorly done its difficult to call them "welds", appear to have pulled loose of the parent metal and others seem to have torn the vertical flange off the transverse- that implies to me that welding isn't the best solution.

The weld overcame the parent metal because the load was in a small short space- loading the weld point to much for the original metal part to carry. I'd suggest sanding/grinding/cutting out the "welds" and put a 'japanese fan' shaped patch of about 90 degrees over the entire area and riveting or bolting the patch onto material of the seat and the rib.

My reasoning is the weld access is very poor, some of the original material looks fatigue cracked and could use an overlapping reinforcing patch. The joint to the seat vertical torn off, at least in part, because the original welds were very poorly done, implying that replacing those welds will be difficult to do well and may only repeat what has already happened.

Cheers,
Kevin Morin

 

[crackedglass]

Re: Aluminum boat - Cracked welds

The welds on the front of the panel are easy to get to, they are right at your heels when sitting in the seat, the rear welds are under the bench seat.
I could picture getting to the rear welds with a mig gun, but the tig torch would need the rod trimmed short on the back side.
The seat itself isn't affected, all of it's welds and rivets are intact. That panel has about 6 welds on each side, only the ones on the end are broken free. With the panel loose, the boat bottom flexes around the trailer bunks. Since these have no ribs, this panel and it's angle braces are what stiffens the hull bottom. In the water, these welds fall back in place and never move.
The original trailer only supported the hull at this point, and that support was too far outboard of the keel. They had it on a roller trailer with only two rollers which contacted the hull at the outer corners or strakes.

I agree some added support is in order, but I feel that now that it's on a bunk trailer, once this is fixed all should be fine. I have another one of these which has been fine for years.

To give you a better idea of how that panel sits, picture a bare hull, no ribs, with a half moon shaped panel installed to stiffen the hull. The seats are attached to the upper sides of the hull and aren't a direct part of this structure. The panel which is unwelded is thin, much thinner than the hull.
I sort of though it was meant to act as a bulkhead panel but since there's a through drain beneath it, that would serve no purpose.
The only reason I see for it is to stiffen the bottom of the boat. I could probably remove the pop rivets that hold down the seat top panel, pull out the foam chunk and have pretty good access to that area. Being a small boat, welding this will no doubt mean that no weight could be in the boat or else it would distort. The other seats do not have this panel, only the rear seat and the very short front seat. This is not the driver seat, so it's not the most used seat either. If I hadn't been reaching over the hull when cleaning it, I'd have never noticed the cracks. They close right up in the water. The boat feels pretty floppy or flexible on the trailer even though the bunks are full length and it also has keel rollers adding some support. My other one is rock solid. The hull is made from two large aluminum panels on each side joined in the center with 4 riveted on strakes and the keel. The center seam is welded down the outside and covered by the keep strip. There is nothing installed to prevent twist or distortion side to side.

Here's another pic showing the panel in full better:

http://i45.tinypic.com/vqh14z.jpg

Worst case scenario would be that I leave it alone and just run the boat, I doubt it will ever cause a major failure. There is also enough metal there to get in there and drill several small holes and bolt or rivet the panel back into the groove. I may do this as a temporary fix to hold the pieces in alignment for welding too.

I called a few shops today that advertise aluminum welding, only one said they would look at it, the rest won't touch a boat hull. One said that once it's been exposed to salt water or sat outside for years it wasn't weldable.
I got mostly nothing but excuses.

 

[jspano]

Re: Aluminum boat - Cracked welds

i would do all the prep work yourself before bringing to the welder


joe