Photo 1 has some pitting. Was boat foam filled and was foam wrapped in plastic.
Have stringers/bulkheads been welded on opposite sides as well ?

Photo 3 is tig welded but maybe wrong grade of filler causing cracking.

All marine grade ali is marked in my experience. Can you find any markings ? Should be 5083

Most pros use pulse mig welding these days on ali.
Binzel push pull guns were the norm back in the day and I have never had a good experience with those mini spool guns but I have only ever used two of the brands out there.
I have a few technical documents re ali welding from when i did my tafe course years ago. I could copy them for you if you want.

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ok said..

grich62 said..

Mark _australia said..
If a marine surveyor said its shoddy workmanship not due to being flogged I don't see how the manufacturer can avoid it now.

On another note I am finding this really interesting as I am an OK welder sometimes but never done ally.
The fillet welds look like good penetration on both surfaces but still let go on one surface. Grich62 says worst he's ever seen, so I'd be interested to know what indicates that so I can learn a bit.
The flat welds look good too and have cracked right thru the middle, were they repairs that induced stress and then cracked? If so why?
Can the experts tell us what looks bad here?

mark the pictures of the intersecting welds show no surface preparation and no penetration of the weld,it also shows that there is a lot of stress as the weld has moved away from the plate .the weld also shows that it was rushed as the pool has thinned out and the weld is just sitting on the top .the other sections were they tried to fill a crack,a crack needs to be distressed while cooling to stop shrinkage pulling the weld apart ,i use a needle gun to beat the stress out while cooling.in all crack repairs the end of the crack should be drilled
these are some photos of the repair of a truck chassis and truck diffs before and after ,you can sea the rough texture from the needle gun which distresses the weld and the surrounding area ,these trucks are still in service after 5 years

Whats your job title? and location? Would pay you to have a look if you think its repairable ?

sorry mate i don't do that work any more only posted to show mark what i meant
you should be able to find a repairer down there to fix this or keep pushing the original builder for compensation

just fill the hull up with pool floaties . next...

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ok said..
Evening Breezers

I have just had my small plate aluminium boat assessed by a marine surveyor on behalf of the insurance company the boats insured through.
I contacted the insurance company as the boat has sprung many leaks in the bottom hull sheet and when I went to get it repaired the repairer said it was cheaper to get a new hull then repair the existing.
This is because all the longitudinal stringers attached to the bottom hull sheet have bust off at the welds.


The boats less then 2 years old & 4.5m's long and made of 4mm plate with fully welded deck.

The marine surveyor has recommended I go to a metallurgist as it appears that the boat has not been welded to a correctly. Once I get a report from the metallurgist confirming that ( if thats the case ) I then have to go through consumer law and send a letter of demand to the boat builder.Im writing on here to see if anyone has had to do this before and if theres any do's and dont's to follow in the process. Im currently a lot of money out of pocket for the boat + extras + previous repairs and Ive been told Im not to use the boat as is because if it sinks and someone gets injured I am liable. Any help would be appreciated as its basically one expensive piece of scrap metal taking up space in my inlaws driveway.

Hi Ok,
So, I have a bit of knowledge in this area and as some others have said, you definitely have a workmanship issue for the broken fillet welds. From what I can see in the photo, the cause of this failure is poor weld shape where the leg lengths (sides of the welds) are uneven to the point where you only have a small amount of fusion to the vertical plate and very little through thickness to the weld. The welds themselves also look ropey and of poor shape so it is possible the welding equipment used was under-rated for the task.

These welds have been done with the MIG process as has been previously stated and it is common to get weld faults such as porosity or lack of fusion if the pre-cleaning or machine settings are not correct. To ensure quality (repeatable) workmanship, the fabricator should have weld procedures complying with AS1665 which is the standard that covers Aluminium welding. I am not sure about all the laws relating to maritime vessels but I am aware of a significant case in Australia where a fabricator was found guilty of manslaughter after repairing the keel of a yacht which subsequently failed while at sea, killing one or more of the crew. It was found that there were no qualified weld procedures or qualified welders (among other things) that significantly contributed to the failure....

The second set of photos showing the cracking of previously repaired areas is a bit harder to pinpoint from the photos as it is impossible to determine the initial cause from these photos.... but as Grich62 has suggested, it appears the initial cause of the cracking has not been addressed and it is possible that the filler material used for the repair may not be compatible with the grade of parent material. If I was to hazard my best guess, I would say that the initial cracks were not drilled at the ends to arrest the crack propagation and that they (the cracks) were welded over without preparation to fully fuse the material.

The good news is that the areas shown are repairable. Provided there is not too much distortion in the hull as a result of the broken fillet welds, a good clean and re-welding (correctly) should put that to bed. The cracking would need a bit more investigation to understand the initial cause and now that the cracking has become contaminated (see the corrosion around the top of the last photo) it will be harder to make a successful crack repair. Best bet is to cut an weld in a small patch, full penetration, to remove all the suspect material.

A metallurgist may be able to give you some detailed information on crack type and possibly confirm material grades for the filler and parent metal but I think your problem has more to do with workmanship buy the builder. A welding inspector will be able to write a detailed report on the observations of the welding conducted and potentially investigate whether the fabricator has approved procedures in use (ie the work complies to the Australian Standard).

Good luck with getting this resolved... I did a lot of Ali work in my tradie days and it staggers me how many examples of poor workmanship and lack of understanding of this material there is.... its scary.

EMboy - Thanks very much for your reply. All of what you said has also been told to me by the metallurgist I visited in Silverdale in Sydney last week. Do you know any welding inspectors near to Newcastle that could provide a report?Ive also had quotes to repair the boat but as the bottom sheets are so badly distorted the quotes are more then the hulls worth. I will never again by from a boat builder thats not well established and doesnt have a proper warranty!