Cracked Weld, Marine Tex or Marine Tex Flex?

[java230]

Trying to patch up a spot in my hull that has cracked a weld. Had it rewelded last year to no avail, it cracked again, I cannot access back side to clean or weld from there so its a difficult spot.

It has a bit of flex between the panels, and is under the water line. Marinetex flex is supposed to be flexible, but not as strong as standard marinetex. It is in a spot that can be impacted by rocks when beaching also (makes me lean towards flex?)

Other thoughts?

 

[alldodge]

Would help to see what you got, but without that I'm thinking slow cure 5200. Get it up in there and tape over to keep it from dripping back out.

 

[gm280]

Post a picture of the actual cracked area so we can see what you are seeing and then be able to offer good suggestions and ideas. Most of the time when a weld cracks and then is rewelded and cracks again, the crack wasn't stopped before rewelding. And usually the beast way to stop the initial crack is to drill relief holes at both ends of the crack first. Then reweld. JMHO!

 

[jbcurt00]

In what boat?

Welded aluminum hull? The Harborcraft?

Or a riveted hull?

 

[Woodonglass]

If the area is "Vertical" getting a lower viscosity patching compound to flow into the area and stay will be difficult. On a good hot day the MarineTex Flex might be your best Bet. Use a Thin Flat stick to poke it in as best you can.

 

[java230]

Sorry I should have put more details!

Yes welded hull. It appears to be between a reinforcement plate and the hull plate, there appear to be small holes drilled in the bow section of the hull, under the reinforcement plate, this I think is where the water gets into the hull. Its not an easy place to see.....

Terrible picture, but its on the weld running R-L, starting at the keel and heading up ~6-7".

You can just see the polished area above "oad" on the trailer here.

I did drill holes at the end of the crack the first time, but did not chase the crack or grind down the existing weld. I appears that the drilled hole did stop it on one side, but not the other.

 

[gm280]

I have to say the hull looks like it hit something and there is a vertical bent line from that welded area. :noidea:

 

[java230]

I have to say the hull looks like it hit something and there is a vertical bent line from that welded area. :noidea:

Yes it took a large hit at some point. Not under my ownership.... But that vertical dent is the casting platform, it does not line up with the Crack

 

[Woodonglass]

Hmmm, being that it's located where it is, I don't think the Marine tex flex will work unless you rivet a patch over the area and sandwich the goop between the hull and the riveted patch.

 

[java230]

Hmmm, being that it's located where it is, I don't think the Marine tex flex will work unless you rivet a patch over the area and sandwich the goop between the hull and the riveted patch.

Not what i wanted to hear I was hoping the flex would hold up better than 5200

better pic of the crack

 

[Woodonglass]

This might be helpful...http://www.survivalistboards.com/sho....php?p=7834536

and this

http://forums.iboats.com/forum/boat...-hull-damage-lots-of-it?p=5693705#post5693705

 

[java230]

The second with the riveted patches makes me want to do that, but its not a flat surface, and the crack doesnt go through to the inside. Its just in the reinforcement plate, but there is a hole somewhere.....

 

[Woodonglass]

aluminum is flexibe sooo...you should be able to fabricate a patch that conforms to the area. Use an ample amount of 3M 5200 on both the hull and the patch and it will fix your problem. Of course that's just and Old Dumb Okies opinion.

 

[java230]

I appreciate the opinion WOG!!!!

Did some more digging tonight, with the grinder and drill.... Crack is 100% on the lap joint between the hull and the 1/4 or 3/16 overlay on the bow. its odd,no crack on the inside, but i found a couple of small holes drilled way up in the bow in the hull, Likely to let gas out when welding??? but it seems i could do a could rosette welds 1" back from the crack that keep breaking and that should help stiffen that up.

I drilled a hole at the end of the crack, about 14/-3/16 deep, water came out, inside of hull is dry, its trapped between the layers..... banging on the reinforcement plate shows movement along the crack and water.


Thoughts on patch without rivets and 5200 only??

 

[gm280]

I guess I am the only one that still has no idea where this crack exist on the hull. What I see though makes me think that maybe you should grind everything down flat and then see what is the real problem before any repairs. JMHO!

 

[Frey0357]

Java,
Just my opinion here but that area obviously has stresses on it causing that weld to separate, so I would NOT put a patch on without rivets or some type of fasteners and a healthy "smathering" of 5200. Doing so will simply get stressed and fail at some point.

If it were me I would follow WOG and go for it!

good luck and keep us posted!

Frey

 

[StarTed]

How about welding on a small patch overlapping the seam? Grind it down well first and heat it for a while to drive out the water as steam.

Just another thought.

 

[java230]

I guess I am the only one that still has no idea where this crack exist on the hull. What I see though makes me think that maybe you should grind everything down flat and then see what is the real problem before any repairs. JMHO!

Yes its an odd spot. There is basically a reinforcement plate on the bow, under the normal hull skin, the back edge of this plate is where the broken weld is.

Java,
Just my opinion here but that area obviously has stresses on it causing that weld to separate, so I would NOT put a patch on without rivets or some type of fasteners and a healthy "smathering" of 5200. Doing so will simply get stressed and fail at some point.

If it were me I would follow WOG and go for it!

good luck and keep us posted!

Frey

Thanks, The 5200 that was on there held up for awhile, It looks like it may have come loose due to beaching on rocky ground or bad prep, not 100% sure. I was thinking that a piece of aluminum of top may help with that.

The other thing is it may simply be a matter of the plates flexing at different rates, the hull is 9 or 10 gauge (just under 1/8") it appears, and the reinforcement plate is 3/16" or so.


​

How about welding on a small patch overlapping the seam? Grind it down well first and heat it for a while to drive out the water as steam.

Just another thought.

This is the best bet I think, but I dont want it to just rip at the patch instead.



So I ground it way down last night. I think it could be re-welded, but there is water trapped between the layers, and no way to clean the hull under the plate. (if that makes sense....) unfortunately I cant weld aluminum! The crack is clean, but jagged, and if you pound on the hull it will move 1/3mm ish. just enough to see.

 

[Pusher]

For anyone still lost, the crack is at the bottom of the hull right above the "OAT" in the trailer's "BOAT" decal. It's the sliver of silver you can see in the black paint.

Take this with skepticism as I don't know anything about welding.

You could go to the 2nd-hand shop and get a hair dryer. Let that run on the water area over night if you don't have the time to heat dry it by hand.

It sounds like the flexing is killing you here, and from the looks of it, that is right where the hull is taking the pounding from the waves while under way. Is there a compound you could fill between the reinforcement and the hull that wouldn't seep out while welding? Sounds like you need to keep the hull from flexing or it will stress crack out again. It almost sounds like the reinforcement is killing you too. maybe you need to rip that out after welding and bed it in with 5200 so there's some kind of a cushion?

Again, I don't know anything about welding. I just know all the aluminum aircraft panels I worked on cracked out at the stress and flex points. I didn't know about stop-drilling cracks when welding too, good tip!

 

[StarTed]

If you don't get all the water out the steam caused by welding will make a hole through your weld somewhere while welding. Aluminum needs to be clean to get a good weld. Fortunately some of the modern welding machines also clean as they weld. Use a stainless steel brush or non-metallic abrasive to clean the aluminum before welding. If you need someone else to do the welding do as much cleaning just prior to the welding as you can.

I'm not a good enough TIG welder yet to tackle that kind of repair unless the boat was upside down.

I wish you well on your repair.