[Squizzy Taylor]

G,day John, I did my boilermaking apprenticeship at a time when aluminium was going to be the next "big thing" in trailers. That was over 25 years ago and if you look around now you wont see many ally trailers in general haulage.

There are notable exceptions where ally does well...fuel tankers are just one example. The problem in the early days (I'm talking semi trailers....ahh tractor/trailers I think you call them) was we thought you could just build them with the same design and techniques you did with steel. This was a major error...too put it mildly. The joint design at welds was the major area.

Emminent Internationally accredited design agencies such as Lloyd's Register now allow up to 60% reduction of tensile strength at the first pass of welding in aluminium....thats a lot. Basically it revolves around the mettallurgical changes that occur in the Heat Affected Zone of the weld...And....the differing performance of aluminium (fatigue life) under cyclic loadings.

To cut to the chase, by the time we built an aluminium trailer that had the durabilty of steel (in terms of load carrying) it was about 3 times more expensive to fabricate and nearly as heavy.

That said, and with advances in welding technology and design, primarily as a result of the aircraft and high speed ferry industry, it is possible to build a good trailer from aluminium. Some solve the jointing of the chassis problem by bolting rather than welding. Where the load is evenly distributed and the roading good; aluminium is definetly an option. Boat trailers are an area where ally excels...as you have mentioned due to the corrosive environment.

However, ally suffers from dis-similar metal reaction so all attachments to the trailer need to be made carefully and with the correct materials.

A properly designed and constructed aluminium trailer is definetly a good option when cyclic loads are not going to be excessive and the load distribution is even. Wether its economical will depend on the individual circumstance.