Trailerable trimaran, rebuilt tandem axle

My old trailer was cheaply, put together, for a 6 mile trip to the boat ramp. As it started at 1200 pound, then morphed into a 1600 pound fully loaded weekend camper. Stove, portapodi, 100 amp battery, fuel, water.

It rolls on 12" 800 pound 6 ply tires, The amas fold up, making it, top heavy.

A blow out would possibly be roll over. If the wind and gravity were just right.

I am a Welding Technition by trade, so steel is comfortable to work with.

I bought a 20' tandem axle trailer 4500 gvw.

I am going to cut about 4 feet from the rear, then slide the axles forward and re bolt. Very simple.

I want a tandem axle mostly for, bad drop offs on boat ramps, soft sand river ramps , and security on long hauls, at night, blow out, flat tire.

I would like a toung extension, or a hinge, for parking storage.


One shackle welds cracked, some other minor stress cracks.

I need to soften the suspension.

I could also use smaller diameter tires, and use one axle as a "cheater axle".

The leaf springs had 4. leaves, I think I will pull the bottom 2 short ones.

Any ideas,


The spring mounts were U bolted on the trailer rails. Easily balanced,

 

It seems to me that you are absolutely on the right track. Your project is fairly similar to mine but I do wish I had your welding skills - mine are pretty crude. I started with an A Class trailer. modified it to twin axles. extended the length and built the supports and rollers to take my 6m catamaran.

The bad news for me is I did not allow nearly enough strength to handle the weight of the boat jumping about on bush roads, so I'm having to reinforce the roller setup completely with bearers right across the chassis.

Good luck with your project

 

The current trailer, lost both fenders, on rouph roads.

Can a trailer suspention be too soft?

 

Not sure about the softness factor but I would guess the softer the springs, the more they will move and the more likely it will be to have trouble.

For travel on rough roads, the worry is a tendency for the ends of the spring-leaves to jump out of the anchor boxes - which is what happened once to mine. I guess there are only a couple of options - to move the outer end-housings closer together OR weld a small plate over the end of each spring to prevent excess movement. I have yet to try either. The third option might be to add shock absorbers.

 

The 1st leaf is rolled into a cylinder that is bolted, a hanger shackle will swing, allowing movement.

I have seen some broken springs, snapped off near the bolt. I think over flexing, can cause this, but might have just been low quality carbon steel.
As in the (FORD TAURUS coil spring recall).