Advice on repairing cracks in Seaark ribs, seam

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TBNole

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As I stated in my livewell thread, this is my first boat, a 1996 Seaark 1652MVT tunnel hull with a 1997 Yamaha 40 2 stroke. I bought it knowing it would had issues, including a hull leak. But I got it at a price that I could make a lot of repairs and still be ok. I enjoy learning new things, so although it has turned into a bigger project than I thought, I am enjoying the challenge.
20190613_200803.jpg
I replaced the impeller, tilt/trim motor, tilt/trim relay, ignition switch and rebuilt the trailer with a new axle, hubs, lights, rims and tires. The motor has good compression, runs great and the trailer is solid. I also added a second bilge pump, a livewell pump and am rewiring the electrical system. The livewell repair is still on the list, it has just taken a backseat to the hull issues listed below.
I knew the boat had a crack where the tunnel hull starts. It was a relatively slow leak and I could run the boat, using the bilge pump periodically. I took it in to a marine welding and fabrication shop and he made 2 attempts to weld the crack from the underside of the boat. Neither were successful in completely stopping the leak.
I could tell that the floor of the boat was not solid and had a lot of flex, so I decided to remove it to see what was really going on and repair the leak. I am glad I did because it revealed a lot more problems that need to be addressed. As you can see in the pics, the frame supporting the floor has almost completely collapsed. I am not sure this is a Seaark factory floor system. The material is .07" for the braces and the welds are pretty ugly. I have emailed Seaark some pictures and they are trying to research it now to see if it is original and offer advice on how to best repair it. I really appreciate this company, helping me out with a 23 year old boat shows their commitment to their products.
20190717_102008.jpg
Failed floor support brace:
20190717_104655.jpg
Of course the biggest issue is repairing the crack in the hull and ribs. I hope the seam leak can be repaired now that It can be addressed from both sides. This is the seam that is leaking. It is the beginning of the tunnel hull area and the leak is coming from this 90* seam you see behind the rib.
20190717_104704.jpg
Two ribs have cracks running vertically. The ribs are not completely cracked, but I imagine it will continue till they are. In addition, many of the welds that attach the ribs to the hull have stress cracks in them.
Cracked rib:
20190718_115120.jpg
Crack in weld attaching rib and hull:
20190718_111445.jpg
I am hoping to get some advice from any of you with welding experience on my chances that these cracks can be successfully repaired. If the hull and ribs can be repaired, I will redo the floor supports using stronger material. It is a great boat for the inshore flats fishing I want to use it for. Hopefully, I can get it restored to better than new and it will last a long time.
Thanks in advance for your help!
 
I would grind that weld down flush, drill a hole in end of crack. Weld up crack, regrind flush again. Then weld a lap plate over joint, one on both sides if possible, (if both sides stagger where welds are to limit heat). If you want even more ruggedness, drill some holes in the lap plate & plug weld them also.
 
CedarRiverScooter said:
I would grind that weld down flush, drill a hole in end of crack. Weld up crack, regrind flush again. Then weld a lap plate over joint, one on both sides if possible, (if both sides stagger where welds are to limit heat). If you want even more ruggedness, drill some holes in the lap plate & plug weld them also.

Thanks CRC. I assume you are referring to the last pic, which is the cracked weld between the rib and the hull. Would you drill the hole just through the weld, trying not to penetrate the hull? What material would you recommend for the lap plate?
 
I personally don’t trust welds on top of welds in an aluminum boat where they are already cracking. Too much heat Can ruin the temper of the material and make it a brittle, causing cracks, hmmmmm ... might already have.

I would repair it with lap pieces, but would use closed rivets and the special air tools to set them. Prime, then goop the area or between piece with G-Flex 650, a flexible epoxy would be my choice. Use same alloy.

I have a full sheet of 5052 if you need some pieces cut.
 

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