Straightening out crunched corner on tinny

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Tinny Fleet

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Location
Florida and New England
LOCATION
Melbourne Beach
I am the third generation of my family to own this boat: a 12' Dura tech. I have pictures from the 60's where my grandpa was taking me out fishing in it. Lots of memories. My son will get it when I pass.

Its a nice lightweight 12' john with a modified vee in the bow. The plan is to iron out some of the wrinkles, including replace transom wood, patch holes, seal floor, paint with Wetlander, and more.

One of the problems is a crunched corner. Looks like it took a fall somewhere along the line and landed on a corner. See pics.

I'd like to restore this to the original squared off corner.

Any suggestions on how to correct on a DIY basis?
 

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To straighten the biggest part I would lay that side on wood on the ground and hold another piece of wood on the inside and bang on it with a 2 lb hammer. Until someone stops by who knows how it should be done. lol
 
I'd be tempted to live with it. That's going to require a lot of beating to get out, and by the time you get done it will likely look worse than it does now...
 
Renting a porta-power hydraulic tool might push it out gently, they come with an assortment of various shaped caps to direct the force. I would be afraid of springing the rivets and it would require anchoring the boat so the ram can push on the metal instead of just jacking it upwards.
 
Given the age AND crease, it will definitely crack if not annealed properly before attempting any repair. Even then, with where it is located, I doubt you’ll ever get it looking good, never mind square or like the other side. I also think you still risk cracking it even if annealed.

If it were mine, I’d not only live with it ... but I’d make up a really WILD story :---) to tell your kids about how you & Grandpa put that dent into it. Dents add character, remember.
 
If you do decide to hammer on the boat follow Water buoy's advice. keep a thick pad between the boat and the hammered wood bar. You must not hammer the aluminum directly or it will immediately look like a rat chewed off the corner of the boat. It's possible that a little hammering might help straighten out the line of the boat, but you will never make the injury invisible. If you're going to do it, be happy with a slight improvement.. and call it a day.
 
Shaugh said:
If you do decide to hammer on the boat follow Water buoy's advice. keep a thick pad between the boat and the hammered wood bar.
And do NOT use a metal hammer, but a LARGE heavy rubber one ... but only on annealed surfaces ... or 'else' - crack.
 
richg99 said:
Old dents and creases will increase its "inherited" value.

I'd leave it alone.

I agree. If it is a small dent and not leaking or causing any problems, I would leave it alone. It is a lot of work and risk to go beating on the aluminum trying to smooth out small dents. You risk making the area soft making it more prone to dents in the future or cracking it. Some metals get soft and some get hard when you bend them. Some refuse to bend and will break when you try to bend them. Different types of the same metal may react differently to working it.
 
One way you could draw the bend out slowly would be to drill a small hole in the deepest part of the depression and then put a small machine screw (with appropriate washers) through that and a flat steel bar laid over the outside of the damage. By tightening the screw gradually, you can draw the aluminum up flat against the steel bar. Then when satisfied, you patch the hole.

I’m no metallurgist, but I think this might help you to avoid some work hardening, denting, etc., although you’ll probably still need to anneal it to avoid cracking.

If possible, you should try to identify the alloy used. I believe, but am not 100% sure, that the 5000 series aluminum alloys usually used in boats do not harden from heat treatment but do work harden over time, so you can safely anneal without losing design strength. 6000 series alloys, in contrast, are heat treated to achieve their design strength. Thus, if you anneal them you fundamentally alter the strength and stiffness of the structure and can not restore it without fresh heat treatment which is not DIY friendly.

As far as how to anneal, the basic process is to significantly heat metal with a torch and then let it cool slowly. I’m not sure if you can anneal aluminum by just letting it cool in ambient air (like steel) or if you need something along the lines of a welding blanket to slow the cooling.

I hope the above is helpful, but please look at it more as research suggestions than reference materials. I know just enough about metalworking to get in trouble.


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