The Ball-Loading of a caravan is one of the criticalfactors that determine its Handling and Stability characteristics.
Serious safety issues arise if the Ball-Loading is either too light, or too heavy.
The seriousness increases significantly if the mass of the tow-vehicle is not sufficiently high to be able to control any instability of the caravan.
There are far too many instances - sadly, too often with damaging, or even tragic, outcomes - where the "tail wags the dog".
It goes without saying, that any caravan - when towed by a suitable tow-vehicle - must handle safely, regardless of whether it is empty, or fully-loaded(up to its ATM Rating).
It is certainly reasonable to believe that a Manufacturer has professionally and realistically tested their different Models of 'vans, before offering them for sale, in order to be able to credibly determine the optimum Minimum and Maximum Ball-Loadings for satisfactory handling performance.
It is also to be expected that Manufacturers have designed the (longitudinal) location and mass-limit for each storage compartment, so that when the 'van is loaded - in a reasonable and typical manner - the mass-distribution remains within the acceptable design range.
A major problem with many 'vans is that the mass-distribution - hence the crucial Ball-Loading - variesexcessively, depending on the possible combinations of the (empty and full) contents of the water tanks.
It is also expected that all Manufacturers would have done their engineering design thoroughly, and thus be able to advise potential-buyers of the worst-two combinations of the contents of the tanks, that is, what the actual Maximum - addition and subtraction - variations of the Ball-Loading are (in kg).
If this information cannot be provided by the Manufacturer / Dealer, these two Maximum - addition and subtraction - variations of the Ball-Loading, can be readily calculated by using the attached "moments" (force X distance) formula.
The capacity of each tank must be known (remembering that one litre of water weighs one kg), along with the distance from the centre of each tank to the centre of the axle (or axle-group for tandem axles), and the distance from the Coupling to the centre of the axle (or axle-group for tandem axles).
Dimensions towards the front of the 'van are positive.Dimensions towards the rear of the 'van are negative.
The formula can also be used to determine the change in Ball-Loading, should any equipment be added to - or removed from - the 'van.
It would be interesting what effect large water tanks have if filled to 50% on rough roads and heavy braking.
The LPG ocean tankers with spherical tanks have to be more than 97% full or less than 3% to maintain safe stability.
Because of this 'sloshing' effect I also travel with either full or very nearly empty tanks. My tank is just behind the axle, and has a low centre of gravity being slung under the floor, so when full has a stabilising effect on the van.
Large diesel tanks in boats have baffles to avoid movement of the fluid in the tanks making the boat unstable. I'm surprised it's not a requirement for caravan water tanks to have the same.
-- Edited by Mamil on Monday 3rd of December 2018 09:37:20 PM
