Boat Trailer Weld Question

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Old 04-10-09, 06:54 PM
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Boat Trailer Weld Question

I know nothing about welding so I'm turning to the people of the forum that have helped me out in the past. I have a boat trailer that has some rust on the main frame. It's made of 2"x5" x 3/16" tubular steel. I talked to guy today about it and he said because of the number of spots, it would be best to cut out the whole section (about 8ft), and replace it with a new tube of steel. This would involve cutting (or however you remove them) the welds holding the frame to the crossmembers and weld in the new piece. He said the new piece would but up against the old and the two would be welded together.

Is that the way something like this is done? Perhaps I have too much experience working with other materials (like wood) to believe that a butt joint like that would hold together, particularly to haul boat around, but like I said, I know nothing about welding. Any advice and info is much appreciated.
 
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Old 04-10-09, 07:23 PM
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Here is the way I tie tubing together. Butt to butt will work, but it is not as strong as an angled spice. Fig 1 is a much stronger splice.




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Old 04-10-09, 07:36 PM
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I get the angled part, that makes sense. That connection will hold? I guess I just think of joining two pieces of PVC pipe where there needs to be a coupling that bridges the two pieces to make the joint strong enough. But again, I don't know anything about welding.
 
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Old 04-10-09, 07:37 PM
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a lot of "will it work" is dependent on the load applied to the welded area. The welds also have to be of a good quality as well (obviously)


you can add fishplates that lap onto both the old section and the new or if you have a piece of tube that fits into or over the frame rail, that could be used as well.

It's hard to determine if you need either of these additive supports without seeing the frame and being able to determine the loads involved.

i have rarely been sorry for going overboard with over engineering but have been disappointed with failing to.
 
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Old 04-10-09, 10:06 PM
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Here's a photo of the trailer if it helps. The red lines indicate approximately where the frame rails would be cut. From that point back is what would be replaced.

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Old 04-10-09, 11:18 PM
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I would think waterwelldudes angled cut and weld would be adequate. Most of the forces applied to the joint would be from the pulling of the trailer.
 
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Old 04-11-09, 06:23 AM
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I agree that an angled cut would be good but there will be a fair amount of force on the repaired section.
The bow of the boat will be resting on the front post and every time the trailer wheels hit a bump the frame in this area will be flexing.

I personally would weld a two foot long piece of 1/8" flat bar the same height as the frame on both sides of the repair as cheap insurance.
Nice clean welds and a paint job would make the repair hardly noticeable.
 
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Old 04-12-09, 09:48 AM
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If it was my boat, I'd do the angled cut joint. Then box it top and bottom with 2" x 2" x 1/4" pieces of angle iron.
 
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Old 04-13-09, 06:29 AM
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When in doubt especially on a trailer or something involving safety I also like to add gussests or some other type of reinforcement. Much of the load on your tubing would be in tension along the bottom of the tubing. A gusset strap welded across the bottom of the joint area would add considerable strength, or side plates over the weld area. It is not needed with a proper weld. This would be a belt and suspenders approach.

I recently had the thumb of my hydraulic excavator fail. It was made from a piece of square tubing and the weld held but it tore the tubing right at the end of the weld. Basically the weld can was stronger than the original material. All of my trailers are made from various pieces of steel but welded together so it is very acceptable if done properly.
 
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