Hello Rooster,
I know that to some extent I have been playing the devils advocate on this topic, but it important to try and see all possible sides of the story.
Your latest posting includes the following explanation, I assume from the manufacturer:-
TheTravellingRooster said:
"It was blamed upon the van being entered and exited without the rear steadies being deployed or sufficiently deployed and the lack of support and the inevitable weights and stresses being imposed onto unsupported floor,this resulted in the cracking/splitting/tearing of the bodywork."
I am with you on this one for the following reason.
It is true that entering a caravan without its steadies deployed will put stress into the caravans structure. But I can think of another and probably far more destructive load which the caravan should be designed to withstand, and that is towing.
I have witnessed caravans being tested for vibrations induced by towing (conducted at MIRA near Nuneaton) When towed over Belgian Pave, the results demonstrated vertical accelerations at the axle in the order of 5 to 6G. This is roughly equivalent to towing over a series of 150mm wide and 50mm deep potholes. The effect of this is slightly amplified at the rear of the caravan because of the caravan's rear overhang and the fact that the caravan tends to act as rigid body - well almost!.
It would be perfectly reasonable to assume that under normal towing and manoeuvring, accelerations up between 2 and 3G could be encountered on British roads.
I could do the detailed maths, but it is my guess that approximately 40% to 45% of a caravans mass sits behind the axle. Now even for a modest 1000Kg caravan that means 400Kg sits behind the axle, and when subjected road bumps the the acceleration will multiply the effect of that mass. 400kg mass undergoing only 2G of acceleration will produce a force of 800KgF and so on. What must also be considered is the fact that these loads are impact loads rather than steady state and they can also become negative as the caravan bounces. Incidentally if an average adult weighs 85Kg the four adult s would only total 340Kg considerably less than the impact loads induced by towing.
Consequently a caravan will experience far greater oscillatory dynamic bending loads whilst being towed, than the loads applied by the weight of people entering or leaving it when stationary.
Thus I find the suggestion by a manufacture that a caravan has been damaged by the weight of people using it, to be entirely unreasonable. Its highly unlikely that all adults would congregate at the extreem rear of the caravan when its only hitched to the car with no rear steadies deployed. If a caravan were to be weak enough to be damaged by people using it, then it would certainly be damaged more severely by towing it.