Cracks in aluminum hull braces

[baytonemus]

I'm trying to decide how to repair some cracks in the hull braces on my CL 1960 Flying Crest. These braces are below the front console under a small section of decking where the feet of the driver and front passengers would rest. The first image is a close-up and the arrows indicate the cracks near a couple of 5/32" rivet holes. The second image shows the position of the brace. This whole brace could be removed for repair, (if it's really necessary).



This next image shows a much larger crack in one of braces that serves as a "floor joist." This one would be MUCH more difficult to remove - ~40 rivets including some partially obscured behind the transom.



I've read lots of ideas on this forum about whether or not to weld such thin aluminum hulls. The thinking seems to be it should be avoided unless there's a gash or similar that has to be patched. However, I have a little experience with HTS-2000 low temp brazing rods made to repair aluminum. The working temp is about 725?F, so it's much better suited for working with thin sheets. Heavier pieces of aluminum require MAPP gas, but for something like this you can actually use a propane torch.

Before I go ahead with that, though. I wanted to see if anyone had used HTS-2000 for similar repairs, or possibly might have some other suggestions. Thanks!

 

[hoytvectrix]

Re: Cracks in aluminum hull braces

I would go ahead and weld it up

 

[baytonemus]

Re: Cracks in aluminum hull braces

Looks like I've managed to make it worse. After spot brazing the first brace in the floor with the HTS-2000, I found that the brace had actually contracted from the heat and pulled away from the hull. The gap is over 3/16" in one spot. Unbelievable...



The process also managed to open up a couple of addition cracks that either hadn't been there before or perhaps were not open on the top where I could see them.

Sometimes it's fun trying to do thing that you don't really know how to do. Sometimes it's not.

I'm not sure what to do next. I may be able to use some screws to pull it back together but I doubt I can do that without bowing the hull metal between the screws.

I suppose I could split the brace in the middle and have something fabricated that would bridge over the top of it.

Another option might be to put some washers between the brace and the hull, and then add some extra rivets or screws for extra strength. I will seal the new rivets on the bottom as well as all rivets and seams inside the hull with Gluvit when I'm done.

Hurry and respond to this thread so you can be the first to tell me I'm an idiot!

 

[baytonemus]

Re: Cracks in aluminum hull braces

I'll update this thread even though it's been a couple of months since I started it. I opted not to do any additional brazing, but instead to use a combination of rivets and screws shimmed with washers, then apply a couple of coats of Gluvit. I guess I won't know how it will hold up until I've had it out on the water a few times, but it sure seems like it worked well. Everything feels very solid.