The following statements are taken from current Internet postings of two builders of steel trailers, and some declarations made by one of the owners.

"Due to the brittle nature of aluminum, it will tear or splinter and doesn't provide the safety needed for long term durability". "Many horse owners think all aluminum horse trailers are the best for weight savings.  Aluminum is a light weight metal, but is also easy to bend and break. Our Z-Frame® is a light weight material like aluminum, but does not bend nor break compared to aluminum horse trailers with aluminum frames". "Aluminum trailers tend to be brittle in nature". "Keep your horses safe from serious lacerations and injury that often happens with aluminum structure, dividers, butt/breast bars, which crush and tear on impact". "Whereas all-aluminum construction is no longer acceptable because of sheering, cracking, heat, and repair issues". "Weaker aluminum dividers will rip and shear causing lacerations when impacted beyond their capacity". "Aluminum can easily bend, which is neither safe or comfortable for your horses".

Let's address those issues. Yes aluminum bends and also has some plasticity which allows it to stretch. It doesn't mean the metal will fail. Apparently the authors of those statements have never flown, or if they have, they are members of the fearsome fliers club and have never looked outside the windows. If they did, they would have seen aluminum wings that constantly flex. Have they broken off? There are DC-3s flying today that are 3/4's of a century old; our best bomber is now almost 60 years old, and is scheduled to remain in service for a few more decades. Here's a video of a wing being tested to failure; you can see how far it bent before breaking.

http://www.livevideo.com/video/D6620094FCD74AE3A707AF8D0B41FEE0/boeing-777-wing-ultimate-load-test.aspx

The authors also are unfamiliar with recreational boating, in which countless aluminum boats have been manufactured. Many generations of boaters have used the lightweight, single skin, stamped aluminum hulls of riveted construction. The hulls flex with every wave, occupants moving within, beachings on the shore and trailering. They are maintenance free, reliable and exist in a hostile environment.

The Coast Guard uses vessels in search and rescue. This is video of a 47' MLB. It was designed to be operational in 60 knot winds and seas of 20'. Hitting a 20' wave has been likened to slamming into a bridge abutment with your car at speed. Dropping off the crest of a 20' wave into the trough, generates an impact of 3 Gs. These boats are designed to survive a knock down and be self righting in less than 15 seconds. The crew uses suspension seats and body harnesses to survive the impacts without injuries. All the boat's systems are designed to be operational even while inverted. The construction of these boats? Aluminum. Method of construction? Welding. Operational environment? Salt water. Life span? Decades

http://www.youtube.com/watch?v=OMxZSlF-R20&feature=related

Boating and aircraft constructions have one thing in common. They depend on the lightweight structural integrity of the aluminum to provide a safe passage. If a component fails, it may result in a mortality. If a horse trailer fails, the owner pulls to the side of the road and calls US Rider. If aluminum were brittle and constantly broke, our entire transportation system would immediately stop. This includes trains, subways, buses, shipping, aircraft, trucking and even the space shuttles.

 "The acid from the horse’s urine will cause an aluminum floor to rust". "Horse urine and aluminum do not mix well with time".  "Horse urine is extremely acidic and when you pour acid on aluminum, it will oxidize and cause corrosion to the point your horses can fall thru". This is a bit melodramatic and would take many years of neglect to accomplish. Aluminum floors have routinely withstanded years of minimal flushes before any corrosion control and acid washings were necessary. I have never heard of any horse falling through a maintained aluminum floor.

"there is roughly a 1 to 1 weight ratio of steel vs alum, given similar strength." "there is no significant weight advantage in the most trusted, all aluminum, manufacturers". "It takes three times as much aluminum to match the strength of steel". The manufacturers of airplanes, boats, trailers and automobiles would all disagree with those statements. One example; GM has as much knowledge as any manufacturer in the world, about high strength steels and hyroformed frames. Yet when they wanted to improve the performance of their fastest car, they switched to an aluminum frame to reduce the weight, and provide additional strength necessary for the larger HP motor and higher speed capabilities. "Chevrolet gave the Z 06 an aluminum body structure -- shaving off 136 pounds from a Corvette Coupe" 

http://findarticles.com/p/articles/mi_m0KJI/is_4_117/ai_n13656604/ 

"We use only the finest finished metals with T-6 aircraft quality with exclusive proprietary extrusions for superior strength and durability in our aluminum frame trailers." "I am an engineering graduate" I included these statements because of the claims. T-6 is NOT an aircraft metal. In fact it is not any metal at all. It is a designation for a 3/4 hard, heat treating process.

"I am in the business of educating customers, allowing them to decide what is best for them." "I guess you can find any type of junk on the internet".

Excellant post!!!! It could not have been said any better.

Gard is right on with what he said. There is no doubt he is very educated and has spent many, many years working with aluminum. I myself work in the aviation industry and support what he has to say.

Thanks and keep the great posts coming!

I've learned a lot here that tends to discount much of the anti-aluminum information that I've heard elsewhere.  My exposure on the net has been more to the people who are anti-aluminum. including one manufacturer.

I can tell you many of the arguments, most of which I have decided don't have as much merit as their proponents claim.  There is one thing that remains of concern to me with aluminum construction on trailers.  Perhaps you can clear this up for me and others who may have the same concern.  The concern I have is aluminum welds.  It's my understanding that aluminum welds can give way unexpectedly and suddenly - at least suddenly to the observation.  It is my undersanding (may be wrong) that aluminum welds can look perfectly good to the eye even when they are compromised.  Does it takey special equipment to assess whether there has been damage to an aluminum weld?  There are stories all over the internet about aluminum welds giving way and talegates falling off or floors falling out of aluminum trailers - whether these stories are being accurately and complete is something I don't know. It's not sufficient to me to say that one simply has to not stress the weld by ensuring that it is free from debris every time it is closed.  My concern is that the damage cannot be observed without special equipment.  I don't know that this is true, so I guess this is a question.

One moe thing that is of concern to me is that I know a woman who had a minor accident in her aluminum trailer.  She simply slid off of the driveway.  Her horse ended up with his foot through the aluminum side of the trailer.  Now, this was several years ago and perhaps there have been changes, or there was something unique in the situation.

Finally, the argument made by the anti-aluminum camp is that aluminum breaks whereas steel bends.

I don't know.  At one point, I would have not bought an aluminum trailer.  I am not at that point now.  I did buy steel, but would have bought aluminum had the right trailer at the right price come along. 

I've heard the "well aluminum corrodes" but I don't believe that such corrosion is as serious a problem as rust.  That's gets into the gavaneal and all that, but steel rusts, and that's a fact. 

It's hard to get something over on Gard when it comes to aluminum because he worked in that industry (aircraft) for so many years.

I've not seen any aluminum floors in the trailers (used ones) that we've bought "rusting " through.I've sure seen wood floors rot pretty quickly from urine if they aren't maintained.We had a nice Delta trailer with a steel floor that was coated with rubber material plus had mats.However,along the steel walls where it met the floor,there was rust.All floors in trailers need regular care and maintainence to stay their best.I just find that aluminum needs the least amount of those.

Welding aluminum takes special skills and equipment. Aluminum doesn't change colour like steel when it is heated, and is therefore more difficult to gage its melting temperatures. There are several types of wrought and cast aluminums used in the construction of better trailers; each one uses a little different welding technique.

A person with a low priced MIG welder and a few nights at a adult education classes, can't perform an adequate aluminum weld. It is unlike welding mild steel. It takes a substantial amount of talent and knowledge to properly weld aluminum. The certified welders with these skills are few and expensive to find, one reason why steel manufacturers can charge a lower price for their products.

A proper weld of any material, will result in a joint, that is as strong as or better than the base material. Aluminum welding, disrupts the heat treatment of the material and slightly weakens the welded area. Over time, this will eventually work harden and regain some of the lost strength. However, the main point is, that a structural engineer will increase the amount of materials necessary to maintain the strength necessary for integrity. This heat loss factor is designed into the overall structure.

If the welds give way suddenly, it is because of poorly constructed welds, not the material. Usually a structural failure will be seen beside the weld, and will indicate a poor, post welding treatment. Welding and various materials can be visually inspected for cracks by non destructive testing. This is usually done by applying a cleaner, then a dye, then a developer that will show any cracks. More elaborate testing can be done by x rays and ultrasonic machinery. Most welds can be simply viewed by knowledgeable personnel, and determined to be proper or not.

Aluminum trailers are built differently by most manufacturers, using various materials and different structural differences. A smooth skin trailer will have a siding of .050" or less, an extruded skin may be .125" or more. Some trailers have a double or triple wall structure with insulation, others may have a single wall construction. Some trailers may use a soft 6061 aluminum, while others will use a T-4 or T-6 heat treated version adding more rigidity and strength. The frame structures vary greatly in their spacings, material choices and shapes, each one effecting the overall trailer strengths.

I've read of another trailer owner who's horse's foot went through the side wall. I'm sure it could happen. I had a steel stock combo trailer with a single wall, steel skin. Our shod Belgian became errant one day and kicked for a few minutes. When she was done, the wall was badly dented and split. Yet we have been told by the steel trailer manufacturers that steel doesn't tear. A thousand pound animal can inflict immediate damage to almost any material.

The proof of aluminum welding strength is all around you. How many aluminum horse trailers are on the roadside falling apart? How many tractor trailer frames and dump truck bodies are used every day? How many boats, ships, airplanes, trains and buses wane because of aluminum weld failures?

There are good and poor aluminum constructions. Fortunately because of competition and the notoriety of poor products, most companies are building products that are very serviceable and long lasting. There are hundreds of thousands of aluminum trailers now, some a couple of decades old, that are proof positive of strong structural integrity. 

Thanks for the response.  As I said, all of my early learning was from one of the steel manufacturers and I discussed trailer safety and trailing with her for years.  Many of her opinions that I believed are not ones that I now share. 

I learned a lot from your post.

Add firetrucks to your list! Some time back, when my brother was talking of getting a horse trailer,  I discussed the potential negatives about aluminum, he just laughed and said he'd driven aluminum fire trucks for many years and they were structurally sound. 

My good friend who carries full loads of cattle to their mountain ranch - rough roads and high mountains selected aluminum, also.  It's only a couple of years old but still looks new.  She also carries her horses in it.

So, I changed from my early indroctination. lol