There has been a lot of discussion on the net and in the literature supporting the misconception that a slant load stall cannot be big enough for a larger horse. By "larger" I refer to a horse which is 17 hands or taller. My wife, Judith, who is the owner and operator of Steel Prize Stables, has been using slant load trailers to transport her large horses since 1987. She currently has a three horse slant load and a five horse slant load which she uses with her 17.2 hand Hannovarian.

One of the sources of this misconception seems to be that many people think that the maximum size of the stall is limited by the width of the trailer which in turn is limited by Federal highway regulations. In fact, the width of the trailer is only one of three factors which determine the size of a slant load stall. The other two are the distance along the trailer wall between the hinge points of the partitions and the angle at which the partitions come off the trailer wall. The better trailer manufacturers will be happy to design a trailer to meet the size requirements of your horses.

Here are a series of drawings which will explain the three factors and show how the stall size changes as these three factors are changed. Note that these diagrams assume that the height of the trailer is 7' 6". While trailer height has no effect on stall size, it certainly does contribute to the comfort of a larger horse while on the trailer.

Diagram 1 shows a "performance" size slant load stall. This stall creates a baseline for the next two diagrams. All the diagrams are to the same scale and they are based on a 7' wide trailer - the first of the three variables. The second variable is the 39" distance between the partitions and the third is the angle of approximately 60 degrees which they make with the trailer wall. These three variables, which are under control of the trailer manufacturer, generate two other stall characteristics which are important. They are the shoulder width (32" in this case) and diagonal length (122").

Diagram 2 shows a larger stall created just by increasing the wall length from 39" to 42". This stall has a bit more shoulder width and diagonal length. Since I kept the angle the same, the partition length is the same. But you can see that just increasing the wall length yields a bigger stall.

Diagram 3 has the same wall length increase as Diagram 2 and also changes the partition angle to about 50 degrees while keeping the same shoulder width as the "performance" stall. Now I've created a stall that has a partition that is almost a foot longer than the baseline stall and has a diagonal that is almost two feet longer. Don't you think that a horse will be smart enough to use that additional space?

These are not just theoretical drawings. For example, the dimensions in Diagram 3 are those in my wife's 5-horse slant load. She uses it to haul a 17.2 hand Hannovarian gelding that she competes in dressage at the Grand Prix level. The increased wall length and partition angle added about 3' to the length of the trailer. That's less than a 10% increase in total trailer length to accommodate five true warm blood size horses.

You can see that by further changing the wall length and partition angle you can generate a stall that is quite long in the same width trailer. Naturally, you pay for this in terms of increased trailer length.

All these diagrams are based on a 7' wide trailer. Going to an 8' wide gives even larger stalls but introduces the argument about wheel wells inside the trailer. Almost all of our living quarters models are 8' wide. We usually take care of the wheel wells at the front of the horse by putting in mangers. The rear wells are angled with the horse in mind and are rubber covered for the inevitable kicks.

As an aside, the first slant load trailer I designed was in 1987 and was only 6' wide. I put in a wall length of around 50" and an even sharper angle than in Diagram 3. The partition was over 10' long and the diagonal was on the order of 13' 6". The stalls were entirely too long. They were so long that I had to build butt bars so the horses had something to lean on while traveling.

A reputable dealer will provide the four measurements that I've shown on the diagrams for a slant load stall: the length along the trailer wall, the shoulder width, the length of the partition and the diagonal length. They must be taken together to give a true representation of a slant load stall.