"Houston we have a problem !"
The ballast issue in data:
Pilot Opinion
A recent poll of almost 200 pilots revealed that over 90% of the pilots surveyed believe XC paragliding indeed has a problem related to ballast. Over 25% stated this issue "affects mainly the lightest pilots (below 60 kg)" while over 65% stated it is "a major and widespread issue".
Weight Charts
These weight charts obtained from union community data indicates an average bag weight of over 30 Kg. The data further indicates, the lighter a pilot is, the more weight they will carry on average. Pilots with a body weight below 60 kg currently carry more than 35 kg on average. This means their equipment and ballast together represent as much as 60% of their body weight! In some extreme cases pilots have reported using bags over 40 kg. Heavier pilots, those with a body weight of over 81 kg, still carry an average bag of around 25 kg (by today's equipment standard this should represent minimal extra ballast).
Scale Effect
The difference in performance between sizes is not only perceived or believed, it can also be measured and calculated (Sheet provided by Ozone). The main factor is that the parasitic drag from harness/pilot increases at a much smaller proportion than the increase in total weight. While heavier pilots are likely to have bigger/longer arms than lighter pilots the effect is marginal compared to other scale effects resulting from their weight difference. The frontal area remains almost the same from between a XXS and XL pilot while the weight is increased from 90 kg to 130 kg or more. This scale effect, purely due to the laws of physics, is responsible for at least 70% of the performance difference between wing sizes. Other contributing factors are line scaling (or rather lack thereof), some "Reynolds number effects" and other unscaled parasitic drag (risers, wing attachment tabs, etc.).
Dynamic Factor
A study by Bruce Goldsmith and Rene Falquier concluded: The smaller gliders will lose more altitude than the larger gliders from a given disturbance. This is consistent with the laws of mechanical energy (larger gliders have more mass, which means more inertia, which means a given disturbance has to do more work to set it off course). The difference between an XS and an L was found to be in the order of 10%. 10% may seem small but can easily mean the difference between bombing out or not.. The full academic paper can be found here: KTH University download portal. Additional context from the author for this discussion can be found here.
Accidents
We currently have no hard evidence of ballast being the direct cause of accidents. However, it is the believe of the community that extra weight is a contributing factor that can only lead to worse outcomes in the event of an accident. It is also believed that heavy ballast (in the harness or on the pilot's person) impedes a pilot's ability to handle critical phases during take off, landing and in-flight incidents and results in worse outcomes.
Ballast cons
While a leisure pilot commonly shows up on launch with a 15 kg bag, in competition a lot of pilots are flying two (2) wing sizes above what they could be flying. The reason are clear: Most pilots believe that they are performing better with a larger size wing. Partly because of a realized performance advantage, partly because the smaller sizes are considered relatively less safe and/or come with higher pilot workload while the very smallest sizes are outright missing.
However, this heavy equipment comes with multiple inconveniences:
Pleasure
Carrying heavy bags (up to 60% of the pilots body weight) is painful and removes a lot of the competing and traveling pleasure.
Cost
Heavy luggage comes not only at a costs for the pilots but also for the organizers. Pilots often need to be retrieved in complicated remote places when they could easily reach a better pickup spot on foot were it not for their heavy bags. In total, we are talking of at least one ton of excess weight for a whole competition compared to what would be possible without the incentive to fly heavy. Many competition pilots are flying with wings bigger than what the majority of leisure pilots use and struggle to sell them second hand.
Catch 22
There is a negative feedback loop: small size gliders are not attractive for competition => manufacturers don’t invest in optimising and improving small sizes => even less desire by pilots to fly them.
Barrier to Entry
Many pilots are put off by the perceived necessity to buy big size wings with heavy bags. A lot of pilots don’t want to buy another size of wing, in addition to what they are currently using for traveling and XC flying, just for competitions. It is believed that the need for over-ballasting is a reason for some pilots to stop competition all together, after being injured or simply losing motivation to deal with the weight. It is also believed that this barrier to entry is preventing otherwise qualified pilots from coming onto the competition scene.
Safety
Take-off and landing with such heavy weight has shown to be unsafe. We have all seen our friends breaking bones while they should not have with a reasonable equipment weight. Also flying with such heavy weight gear taxes the pilots arms and shoulders much more and reduces articulation for the lightest pilots.