Clutch went out last year and had to be towed in approx. 16 miles from the mouth of the river to out camp on Bateman. While being towed in, the guy in the 22' or so Scully's hull pulled me in. I was happy to be pulled in because I had the youngest with me. The river was rough as shit that day due to all the crew boats. The kids road with him and I stayed in the boat to help keep it straight. He pulled me in approx. 35 - 40 mph in about 3' waves. They didn't feel a thing, but I took a beating. I didn't say a word, because this guy offered to tow me back to our camp. When we got back to our camp, I offered the guy $$ and fuel, but he wouldn't accept. Great gesture by a guy I didn't know. Here is where the problems started.

My 1748, 3/16 bottom, 1/8 sides was beat to hell. Every stitch weld on my fully welded false floor was broken. No problem, the man did tow me in. Got home and went to work. Cleaned everything up and re welded my floor back down to the ribs. It wasn't until I went to see Todd and Jerimiah to tune my new Kawi. Todd noticed that my floor was flexing. Ever so slightly, but you could see it. Well that was during the hunting season, so I just dealt with it. Took the kids out riding the other day and it started doing it again. So I decided that I need to find out WTF is going on under my floor. Pulled out the ole plasma cutter and went to work. When I cut the floor and pulled it up to see, I could immediately see that a crossbrace was broken. So fuck it, I decided to cut the entire floor out. What I found would shock you. I knew that he was beating me ass to death being pulled in, but I didn't think it was this bad.

With a 1748, I had 3 cross braces and 5 longitude ribs. 3 out of the 5 ribs had broken welds almost the entire way from my seat to the rake. Completely shocked. So I decided to remove all the broken shit and start over, rather than try and repair all that damaged shit. When I cut the crossbraces out, the entire rib section from the rake to my seat came out in 1 piece. All welds were broken. The only thing that was holding the floor from completely flexing and breaking was that it was fully welded out.

Sorry for the long post, but wanted to give you a little backstory so I can figure this out. After talking to several people, they suggested using 4043 wire for welding the ribs down. I have always used 5356 on all 5086 hulls that I have built. This is the only hull (out of about the 10 I have build)that has every had a weld break. Which makes me think the 16 miles of constant slamming in 3' waves busted them up. Then the normal riding of the floor flexing, prob finished them off. I have always been told and have always used 5356 on every weld in my boats. So now that I have completely stripped my hull down the 3/16 bottom and the new ribs and braces should be here tomorrow, what wire should I go back with? Should I try the 4043 due to the river running, so that its a little more "flexable" or continue to use the 5356 as before.


Hull before:
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Stitching weld back after being towed in:
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Floor, side seat and battery box completely removed and ready for new ribs and crossbraces:
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who built this hull?

I've welded one hull with 4043 and that was woodies and he hasn't had a dent not broken weld and he's beat the crap out of it.

The 4043 flows so much better but supposedly is not supposed to be welded to the 5000 series alum.

I would say go back with 5356 and stitch it a little closer together maybe?


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After reading the post, I would say he did.

Yep. One of several. I'm just curious if the 4043 would better for the flexibility. But every other hull I built didn't have this issue. But they weren't beat to death in big waves.

Hey BM.....those were extreme conditions that will probably never happen again. Your original construction was probably more than sufficient for anything short of that environment. Go with what you know man.

I know that 4043 is supposed to corrode in salt water. It is a little wetter but as said before it's not supposed to be used with 5000 aluminum.. I do know that it's a big no with saltwater because the weld chalks up and corrodes itself and cracks the welds.. If it's on the internal ribs I doubt it would ever see that much saltwater but I still wouldn't personally want to chance it since you're on Bateman island. And short of being towed again idk i doubt you'd ever hit 40 in 3 footers again. If it's true 3 footers that's a big ass wave for anything short of a 20 foot boat.. Only thing that would keep welds breaking in that application would be a deep ass v.

BM, what size longitudinal bracing did/do you have?


Most liberals seem to suffer from the same mental condition....it's called stupidity!

Yeah that's what concerns me about the 4043. Used it for around the house shit, but I have always used 5356 on the hulls. But your right, this one was the first for such extreme conditions. For him, no he was in a 22 footer, now he cut the waves some, but the rope was so long that the cross waves had time to come back. Nice gesture, but he destroyed my rocket.

North, Ive always notched my ribs into the longitude braces. It just makes for a cleaner look. Never had an issue until this, but also never expected to be pulled in that either.

Troy, I use hat section. The first few I built, I used 1x2 tubing standing the 2" up. The went to hat section several years back to cut some weight. I also believe Instagator and sopme others use this as well. I just have a hard time believing that it was anything other than the conditions.

I was just curious to see if anyone else had used 4043 on the ribs and bracing.

Where y'all getting that your not supposed to weld 5000 series aluminum with 4043???

Also the statement about a 4043 weld being exposed to salt water, becoming corroded and cracking is not true either. I'm not an engineer, but have a long boat building and welding career, and on a lot of big vessels that live their lives in salt water. 5356 is a better alloy for use in salt water, but 4043 will hold up a lifetime in a pure saltwater environment as well.

The 4043 will flex more. That's what I use on most of my 1/8 and 3/16 mud boat hulls. On all 3/16 and 1/4 bigger outboard boats, I will often switch to 5356. When we use to build a lot of airboat hulls, where there was a lot more flexing issues and stress in the hull then on a mudboat, you could really see a difference in the 4043 vs 5356. The 5356 is much harder, but in turn will crack faster then the 4043, or at least that has been my experience.

Not doubting your welding ability at all, but are you sure you had enough heat and got a good tie in? Thats another issue with running 5356, you have to pay a lot more attention that your getting proper fusion on both sides, it will often have a tendency to whant to lay up just on the stringer, or just on the bottom sheet and not tie into one another unless you make it do so, where the 4043 will flow across a little better.

I did some searching on the Web and in almost everything I read folks/instructions said not to use 4043 with 5086. Not trying to start a disagreement capt. I'm new to welding and I have no educated opinion. Seems some say it's fine while others certainly damn it.

I'm no expert on aluminum alloy make-up and metallurgy. But, some aluminum alloying elements do contribute to stress corrosion cracking in a chloride environment. Specifically, copper, magnesium, silicon and zinc.

If the 4043 is a softer aluminum, all things equal, it would be less susceptible to SCC. But, if the metallurgical make-up is different...like, maybe they add more copper to make it soft...then, it could become more susceptible.

Sorry, like I said....aluminum is not my area of expertise. Don't have too much aluminum floating around in the refineries to give it much thought....other than aluminum fins on fin-fans and on cold boxes of CRYO units...just not much out there to worry about with regard to aluminum and damage mechanisms.


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Like I said engineer or metallurgy expert, just giving some advice from my experience as a pipe welder and long time aluminum boat builder.

And y'all are right to a point. All big crew boats or any sort of COI carrying passenger boat or ABS registered hull will be all 5086 and 5083 plate and welded out with nothing but 5356 wire. It is the better or prefered wire for a saltwater environment.

I guess what I was trying to say is, you are not going to have failures or cracked welds just from using 4043 in a saltwater environment. It may not be as good as 5356, but it will last a liftime with no trouble if just moderatly cared for. I've seen plenty severe corrosian and delamination problems with even 5086 plate just from a saltwater being sandwiched agaisnt it by foam and the lack of oxyegen available. There are plenty aluminum outboard flat boats running around south La built 20-30 years ago that were welded out with 4043.

As far as flex and cracking issues. Big crew boats, and the bigger offshore outboard aluminum boats are built with such a heavy skeletal frame work and skinned with heavier plate, the idea is for the hull to be riggid and not flex. I 1000' steel ship fan literally flex and twist from end to end, but aluminum can not do this, it would fail.
With the mudboat hulls and airboat hulls, if you can build something so heavy and rigid that there will not be any flex under any circumstance, then there would be no issues with cracked wells. I have just found over the years with the mudboat bottoms, that the 4043 just seems to be a little more forgiving. But if both are properly welded I don't think there is enough difference between the two to really matter.

Custom Flat, or Tims Custom Flat as most people know it, weld out all there 1/8' flat boats with 5356. I'm sure everyone knows how many of those old boats are running around, and I'n my opinion a 18' flat with a 115 outboad on it running any choppy lake or bay in south La is taking way more stress and beating then a mud boat in even the toughest timber swamp. There are plenty of Custom Flats with cracked ribs hear and there, but all and all they hold up and have proved the test of time.

Capt, yeah had good penetration. The welds actually split down the middle. Some of the weld was still on the ribs and some still on the hull bottom. I think the crack started with the jarring. And what ever didn't crack with the jarring, finished with the floor constantly flexing up and down ever so slightly.

And I'm an engineer, but no metallurgist, thus me asking. I've always used 5356 because "that's what I was told to use". So in your experience dealing with the salt water, what would go with?

Insane that the boat pretty much came apart. We're any of the corner welds hurt? Or just the stringers?
I had a 2006 godevil that had these problems from the previous owner running heavy chop with a stage 3 motor although it wasn't as severe and was corrected before I got the boat. It actually cracked the hull in a couple spots.


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I'm really suprised that happened. I'm supprised to hear you say they cracked right down the center of the weld like that. My guess is it probably would have cracked with 4043 welds as well, but thats just a guess.

I'm more supprised that just one hard trip being towed through the chop did that to your boat. With that weld in floor, and especially the cat walk gunwales, that boat should be stiff as hell I would think. Running fast in the chop will tear those hulls up faster than anything else, but I'm still rather suprised it did that much to a well, heavy built boat.

Guess what I'm getting at is I don't think your welding wire choice was the root of the problem. I don't know what is either though. Looks to be a very well built heavy boat, and I'm really supprised you find yourself in this situation. Especially on this one hull, with out any issues on any other boats you've built.

I don't care how you weld it. 40 mph in a flat bottom boat, through 3 ft waves, is gonna break welds. It's aluminum not titanium.

Should have all the new stuff welded in by this weekend. Finished rolling all the ribs last night.

Finished replacing everything. I had forgotten how well this thing use to run. Just need to put my floor back down. Went back with 2x2 ribs and crossbraces instead of the hat section. All of my other hull had this, but this particular hull, I wanted to shed as much weight as possible. So I decided to hat section, but being I run the river 90% of the time, I didn't want to go through this shit again, nor do I wish that upon anyone. Its stiff as shit now.

Boat repair 03.jpg
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Nice work banded...looks like your good for another 100,000 now

Nice work!! Wish I could weld.

Just an observation: Do those hat longitudinals run the full length of hull or are they sectioned at each cross member? Looks like they are sectioned between cross members. Ideally, one would prefer they run the whole length, yes?

2x2 is the norm from all the old builders down there. You don't want to build it to flex. U may not have had enough weld on the double bottom. Cutting the longitudinal stringers and adding the extra weld in those areas also weakened it some. BB would run them on top of the longitudinal stringers so they don't have to be cut. Adds apt of weight though.