Dent and small tear in aluminum hull

[Todd 1669]

I found a dent with a small crack/tear while doing repairs to my 1972 starcraft supersport. It was buried under a bunch of silicone.
My plan is drill out the 4 rivets then push out the dent as best I can hopefully without damaging anything further. Then drill out the ends of the cracks to prevent from spreading.
Then Im planning on making a alum patch that will be riveted or stainless truss screwed over the entire area with a healthy layer of 5200 sandwiched between the patch and hull.
The entire interior is getting a gluvit treatment so that will be the final step to what I hope is a watertight repair.
Is 5200 the correct product for the patch?
Truss screws or rivets?
Dont rally want to get it welded that close to the seam.
Anybody have any other ideas or recommendations?

 

[fishrdan]

Your plan sounds fine. I used JB Weld when I had to patch similar cracks on my jon boat: aluminum patch, JB Weld, truss head screws. 5200 is more flexible, JB Weld has a more aggressive bond, pick your poison.

Inside the hull, see if there are brackets going from the rib up to the side of the boat, 3-4" bracket to tie the rib into the side. Pretty sure I've seen in other builds that this was a modification SC made, due to cracks developing in that spot, later models had the brackets from the factory. I'm sure someone will chime in with an example pic of the brackets.

On drilling the end of the crack, when I patched, instead of drilling a tiny hole at the end of the crack (which is sufficient) I drilled it big enough to put in a screw. More added support at the crack. One was too close to the rivet/screw, so I just drilled the small hole.

 

[Todd 1669]

Looking at a resto of a 1985 SS I see the rib brackets your talking about. Great idea and I'll bend one up to slide under the rib when I drill out the rivets.
I also like the idea of using a bolt at the ends of the cracks. A gob of 5200 with a bolt/nut /washer would be pretty strong.
Thanks

 

[Watermann]

The rib end cracks are a known issue with your early 70s vintage of Starcraft. They're commonly found in there boats when it was used with rot compromised decking and side panels. The rib end braces were introduced later in the 70s and that pretty much solved the problem of rib end cracks and the other issue, the side splitting out on the spray rail chine that's right above the seam line.

I patched my Chief's rib end cracks as you described above and added the braces as well so there's no worry about the side split issue. Having solid decking and side panels and all should be a good.

Be sure to closely inspect every rib end to make sure you have no other cracks.

 

[Watermann]

Your patch may have to be larger to cover the puckered area. Held on with Clecos.

The added hull stiffener braces. The factory has the braces under the ribs but the ribs have bends to allow the extra thickness of the brace. Even with the braces between the ribs they isolate the spray rail chine and add to hull rigidity.

 

[Todd 1669]

Thanks for the advice waterman..
I'll be getting a Ceco set up in the very near future.
Looks like a great way to get the patches on and off while fitting.
Braces will be added also.
Your prep job is incredible.
Looks like a new hull rolling off an assembly line.

 

[Watermann]

Thanks for that, it was do it right time with my old Chief which has the same hull as your Holiday.

Not many guys will take the extra step to add the hull braces but I've seen too many threads where these older SC boats without them have the sides splitting out and some goof before them just smeared goop over the crack to "seal" it.

The worst story I've heard was about a Holiday where while under way out in the lake daylight could be seen through the side of the hull at that spray rail chine. The guy ran the boat up to the shore, beaching it before he lost the boat. The water came pouring in through the cracked hull and it pretty much sunk right there on the shore.

There are a number of threads here with boats that have had the side split out but after being told about the fix they often disappear with no other updates.

Here's an old Chief with the side split out and some flex seal tape over it.

 

[Todd 1669]

I fish Lake Erie a few times per week from March ice out until mid December and having that side split like that would be a potential death sentence. especially in 38 degree water. My boat is gutted and getting everything watertight with a new floor and transom is my winter project. Its not a full restoration project but I want to get her as solid as possible.
I was thinking of putting in a rod locker center floor but now Im rethinking that. I really dont want to give up the flotation foam that the locker would replace.
Maybe a full restoration is in the future when my kids are off the payroll but thats a bit expensive right now.
Are you just going to notch the floor a bit to fit around those braces?

 

[76SeaRay]

Check some of your local welding places that do aluminum welding. That would be the most permanent repair. I work for company that makes aluminum balconies which have some welded parts. I am having our local welder (that has experience with marine fuel tanks) build me a new 60 gallon tank for $700. Guessing your small repair job wouldn't cost too much.

 

[Watermann]

Check some of your local welding places that do aluminum welding. That would be the most permanent repair. I work for company that makes aluminum balconies which have some welded parts. I am having our local welder (that has experience with marine fuel tanks) build me a new 60 gallon tank for $700. Guessing your small repair job wouldn't cost too much.

The AL is cracked from flexing numerous times over years which makes it work hardened, welding will make things much worse and add nothing for strength, just fill the crack. It will crack out from the weld in no time. The patch will isolate the area of the crack and transfer the stress away much like a split does for a cracked bone. Also welding will ruin the seam sealer which is only an inch away from the crack. Welding on riveted boats can be done but not in this location and for the reason the crack occurred.

 

[Todd 1669]

Yea. That crack is way too close to the seam for me to be comfortable putting and heat to it. From what I can see theres a gasket of some sort in the seam and I bet that would be a nightmare to get cleaned and sealed out once it melted.
The damaged area is actually from an impact a prior owner had. Theres a dent that put the stress on the riveted area and caused the crack.
The dent doesnt show very well in the picture. Of course it probably only cracked from the impact due to the weakening from the flexing over the past 45 or so years.
I ordered some wingnut draw Clecos thinking I might be able to draw out some of the dent and get the surfaces of the hull and the alum patch pretty snug for riveting without damaging the weakened metal. Sounds better than beating it with a hammer anyways.