Indeed Ian

However, I think a lot of swaying trailer diseases is caused by vortex shedding.
Which is why architects tend not to make too symmetrical buildings.

This is usually triggered by a disturbance to the streamline flow - such as
passing a large vehicle.

Having a turbulator about 30% forward of the back of the trailer works very well
on mine. Don't know who fitted it - but there is a little (about 8mm high)
aluminium profile just ahead of the opening section. Probably fitted to deflect
water past the gap. Mine is a 1971 Anschou trailer with the little wing shaped
doghouse for the fin, but it tows very well.

nimbusgb wrote:
Have you noticed how the boxes on new trailers are now square