Most effective Boat Trailer reinforcements

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I have a 23 foot dual axle boat trailer that I want to make a bit sturdier. It’s currently made of 5” Channel, 2” angle and 2” square, all 1/8th” galvanized. The axles are 2000# and I am swapping them out for 2 rated for 3500#. I want to make sure the trailer is strong enough to handle the additional weight capacity of the new axles.
when we built the trailer 7 years ago it was for a smaller boat than the one I want to haul with it now. I originally thought I would just sister up some new heavier channel, beef up the cross members and add more gussets. But after some research and conversations I wonder if it would be easier and stronger to frame up a new main trailer section and then just utilize what I need from the older trailer.
Do any of the very knowledgeable trailer people on this site have an opinion on the best way to beef up a trailer? I was the one who built the trailer but not the one who designed it, my friend who did is not around at the moment.
Any feedback and ideas would be helpful and greatly appreciated. Thanks in advanced for taking the time to read and respond.

[MMW]

Without pictures or plans it is impossible to tell you how to make it handle a larger, heavier boat. Best bet is to go to look at new trailers the weight rating you need and see how they are built and material size and somewhat copy them.

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I have been looking at other trailers and that’s where I have gotten the notion that it’s probably better to frame up a heavier sturdier main section. Then add pieces of the old trailer to that. When I look at bigger heavier trailers I don’t see where sistering heavier channel will do anything other than make it bulky.
I was hoping that someone had experience with different approaches other than full out rebuild, but I guess sometimes the obvious choice is the right choice.
thanks for the reply

[metalmagpie]

The problem is the 1/8" material. There is only so much you can do. 3/16" is so much stronger.

That said, you can "box in" channel in high stress areas. By this I mean choose flat bar that fits between the two channel flanges, welded in. Also, where the springs are attached to the frame, you can cut those loose and put a piece of flat stock between the spring hangers and the frame. The flat stock should span the whole length of the springs. The idea is to reinforce the frame from bending right at the spring hangers by distributing the weight.

I am not real familiar with boat trailers. Flatbeds (which I am more familiar with) can be loaded anywhere but it seems to me boat trailers are always loaded at just a few points where those rolling support arms are connected. Those spots are also good candidates for reinforcement.

Those are just general principles. The cheapest way to go is probably to buy a used boat trailer designed for your larger boat, and sell your trailer.

metalmagpie