Stress Cracks

[MrTotty]

I am working to restore a 1986 Yazoo 1542. When removing the transom I noticed that a couple of the rivet holes in the hull of the boat have stress cracks. I'm trying to figure out the best way to fix these. I've thought about drilling a hole at the end of each crack, grinding a cut in the crack itself then adding a plate that starts from the transom and goes 6 to 10 inches in front of the cracks on the bottom of the boat welding the cracks (now cut and drilled) to the plate. The plate would then be welded around the edges to the hull and redrilled for rivets.

Is there a better way to accomplish this? I don't want to make things worse trying to make them better. I'll try and add some pictures later today.

Thanks

-Chris

 

[Syncrowave]

I'd probably go with some kind of epoxy repair, adding in new metal and gluing it in place (possibly with some rivets), rather than welding. Welding, especially on used boats, can be dicey. It also normally weakens the metal in the area adjacent to the weld (HAZ or Heat-Affected Zone).

 

[MrTotty]

My issue is (and it may not be an issue) these are the front mount holes (closest to the bow) for the knee braces. There is nothing in front to add support unless I add a piece like i was mentioning before under the hull and rivet further up, not sure any glue product is going to stand much of a chance in this area, if i can stop the crack and add a bit of extra support maybe it will be fine. i can't add metal to the top since it will throw off all of the holes. I've got plenty of rivets (solid), just need to find me some aluminum to make the plates.

 

[bulldog]

I had some cracks and leaky rivets and I used brazing rods to fix them. It worked like a charm. Search "durafix" and you will see the thread.

 

[bulldog]

https://www.tinboats.net/forum/viewtopic.php?f=3&t=17096&p=235082&hilit=Durafix#p235082

 

[MrTotty]

I'm not sure that stuff will bond a crack in this location. I've got some of it, and last time I used it it warped the crap out of the aluminum. I was able to take a punch and knock it right back out of the hole, it didn't bond very well at all. If I apply heat I'd go with welding. Not sure how well this will work, but I may extend the knee brace a few inches, reinforce the top to get the load off of that last rivet and see how that works. I will be bucking all the rivets (new) to replace what came out of it. I think the most important thing is stopping the crack.

 

[MrTotty]

What I am planning is to cut a piece of aluminum that will fit between the chines that goes a few inches forward of the crack and also will attach to the rib in front of the knee brace via solid rivets, I will then use a glue or sealant to waterproof it. I'm hoping that will stop the cracking (I also stop drilled the cracks). If that does not work, I'll have it welded.