The Human Carrot
A funny wingsuit BASE story by Douggs with a serious message...
A previous article (HERE) gave a checklist for jumpers looking to perform a very thorough pre-season gear inspection. BASE gear can see more abuse than in related activities like skydiving, paragliding, and climbing. Because of the forces our gear is subjected to and the wide range of material types and construction methods out there, it’s more important than ever to closely inspect our rigs on a regular basis.
Following one jumper's inspection Apex BASE received an interesting e-mail… Greg Jackson was inspecting his gear when he stumbled across this:
Fortunately Greg discovered this cracked hard link before jumping his gear, but these are the types of finds that all too often escape the notice of BASE jumpers. BASE gear is a mechanical system – and such systems can and will fail in the absence of proper maintenance and care.
The hard links on Greg’s canopy are a zinc-plated steel that has a lower rated strength than stainless steel links. The softer zinc links have a tendency to crack at the barrel, especially when the barrel is over-tightened. Zinc-plated steel is also susceptible to rusting (visible in the photos) which can deteriorate the riser webbing.
The softer zinc links have a tendency to crack at the barrel, especially when the barrel is over-tightened
If using hard links, both Apex BASE and Squirrel only recommend (and use exclusively) stainless steel links. Both companies use Peguet Maillon Rapide stainless #5 links, which have a working load of 450kg and a breaking point of 2250kg.
Even the best quality links can be cracked by over-tightening however, and be aware that under-tightening is a bad idea as well!
To properly tighten your hard links, turn them until finger-tight, then do an additional ¼-1/8 turn with a wrench, not more. Because “finger tight” is subjective, the ¼-1/8 range will depend on how “finger tight” you get it before applying the wrench. If you have man-hands, you probably only need an additional 1/8 wrench turn to secure the link. The main point is to not over-tighten the link.
The main point is to not over-tighten the link
When rigging lines or risers to links, open them all the way and take care not to snag riser material or line material on the threads, which can be sharp. Links that are not properly tightened can slowly work their way open. An open (unscrewed) link can bend open and fail under load. Orient all of your links in the same direction (up/down or left/right), so that visual inspection of the closed gates is easier.
take care not to snag riser material or line material on the threads, which can be sharp
Recently, we’ve been seeing a migration of jumpers away from metal links to soft links, such as those built by Apex BASE or Squirrel (which resemble the soft links on tandem skydiving canopies). Soft links aren't quite as intuitive at first, but for jumpers who are willing to put in the extra time there are advantages. They provide greater strength with less weight and bulk.
Not all soft links are created equal, so choose soft links from a reputable major manufacturer (not homemade ones). Be aware when using soft links that slider descent is unchecked by silicone bumpers and there can be wear on riser webbing over time.
Some people find hard links more user-friendly, as they are generally easier to remove & re-install. Ultimately it's a personal choice. All links, hard or soft, only work well when they are installed exactly as per manufacturer recommendations. If you have any questions don't hesitate to give us a call!
Article by Joe Putrino, Apex BASE and Matt Gerdes, Squirrel