Category — Equipment

A Brief History of The Cave Diving Line Arrow – The Forrest Wilson Story

Here at ProTec Dive Centers we are passionate about cave diving! And, we are massive geeks about cave diving history and technology. Recently, I sat in on Cristian Toro’s lesson on cave diving navigation. We got to talking about the history of cave markers and the origin of line arrows. Following our discussion, Patrick Widmann, Resident Cave Explorer and Director of Training, contacted Forrest Wilson (the inventor of the line arrow as we know it), to learn the story of the arrow’s development. The following is summary of the personal correspondence between Patrick Widmann and Forrest Wilson.

Cave Diver Installing Line Arrow - Credit Global Dive Guide

Finding The Way Out With Arrows

The use of arrows to indicate the direction of the the exit originated in dry caving. Early cavers used smoke from torches or carbide lights to leave smoke arrows on the cave walls.

The Evolution From Dry Caving to Cave Diving

When the cave diving pioneers started cave diving in Florida, nobody left permanent lines in underwater caves, therefore there was no need for markers. The divers just reeled in the line as they left the cave. According to Wilson, John Harper was the first to leave line in caves, but he didn’t think of line markers. Other cave divers used things like clothespins, or the outrigger clips used by fishermen, especially once T’s and complex navigation became popular. Following a cave diving accident in Florida most of the T’s were with gaps, requiring jump reels.

In 1976, the death of a lost cave diver at Peacock Springs in Florida prompted the development of a marking system. Lewis Holzendorf invented the idea of using triangles made of duct tape folded on the line as “arrows” thus they were known as ‘dorf’ markers. Dorf markers suffered two major flaws: they folded up or deteriorated over time. However, it is possible to find the remains of scrappy ‘Dorf’ arrows on the lines in caves such as Xunan Ha, a cave re-explored and mapped by Hans Kaspersetz and others.

Innovation and Durability of Cave Diving Line Arrows

At an early National Speleological Society-Cave Diving Section Workshop, Sheck Exley asked Wilson to lead a discussion. The workshop was on the development of durable line arrows. Wilson’s idea was to use a thin plastic triangle that could be folded on the line, and snapped closed, much like a Dorf marker. One of Exley’s requirements was to keep the name of the marker the Dorf marker, since Lewis was a good friend of his. Original Cave Diving Line Arrow Illustration from NSS-CDS WorkshopDuring the workshop Roger Werner drew a triangle on the blackboard with slots, but they had no holes or notches and would never stay on the line.

Wilson tried several things, including three slots, ending in holes. They stayed on a line fairly well, but took too much time to install. Next he tried two slots with holes centered on the slots, but they didn’t stay on the line very well. Accidentally, Wilson drilled the holes offset from the slots, and those did stay on the line.

Photo of an original cave diving line arrow prototype with 3 slots and offset drilling

I’ll Never Be Able to Sell Another Line Arrow!

Forrest Wilson hand made 100 arrows and took them to the Branford, FL dive center to be sold. When Wilson brought a second batch of line arrows to the shop, the shop owner told Wilson they would never be able to sell the arrows. The shop owner said,

“There are only 10 caves, and if you put 10 arrows in each cave that would be 100 arrows, and he wouldn’t ever be able to sell another line arrow.”

All of the hand made arrows Wilson created were sold. One of Wilson’s students owned a cave rope manufacturing company.  He requested 1 “perfect” arrow to use for an injection mold. Eventually, Dive Rite bought the mold from him. The rest, as they say, is history.

January 6, 2018   1 Comment

CCR cave diver training Part I – Modify a brand new Rebreather for cave diving

Deep sinkhole photo shoot preparation Part I – Modifying a brand new Rebreather for cave diving means being drastic and chop chop your new baby.

Again I am working on a CCR cave diver training program. This time it is Paul Nicklen, a award winning National Geographic photographer who is renown for his Arctic wild life photography.

Paul contacted me to get trained to the CCR cave diver level in order to shoot a National Geographic assignment in a Central Yucatan sinkhole. Most sinkholes are openwater dives but due to depth, decomposing material at the bottom that can be stirred up easily and the potential rock overhead they should be treated as cave dives in particular when it comes to zero visibility related drills and skills.

When Paul arrived we took his brand spanking new AP Diving Evolution Rebreather out of the box and modified it for cave diving. The biggest challenge and changes are related to the fact that the cave cave diver needs to be horizontal in the water column and Rebreathers are notorious for not wanting to be horizontal in the water.

Modified CCR Evolution

Modified CCR Evolution

The first step was to transplant the units internals from the yellow box into a Tec frame tube allowing easy access and the attachment of larger 3 ltr steel tanks. A stainless steel back plate was added to streamline the original harness, centralize mass and move the unit higher up on Paul’s back while drilling new holes into the back plate.

Modified CCR Evolution

Modified CCR Evolution

A small weight was added high on top of the left diluent tank to further force Paul into the horizontal and counter balance the left hand side bailout tank.

Further modifications are the larger Inspiration scrubber canister prolonging bottom time from Evolution 2 hours to Inspiration 3 hours and turning the Evolution Plus into a Inspiration. A AP Diving BOV – Bail Out Valve was added to allow the diver to get off loop even under severe Hypercapnia conditions. Inline shut off valves where added to be able to isolate the ADV – Automatic Diluent Valve and BOV in order to isolate them quickly should a free flow or leak occur facilitating the internal and external boom scenario drills and skills.

Modified CCR Evolution

Modified CCR Evolution

The first day and a half where spend to assemble and modify the Rebreather into a kick ass cave diving machine. Putting the Rebreather onto Paul’s back, taking it off, modifying smaller or larger details, putting it back on.
Once we got to the water diving at Casa Cenote – Cenote Manati Paul had no trouble at all to get into the horizontal position by default. The time we spend modifying the unit was well worth the effort as the outcome of immediate horizontal comfortable trim was great to see and watch.

Modified CCR Evolution

Modified CCR Evolution

As we went through a refresher of Rebreather related emergency drills such as the Hyperoxic, Hypoxic, Hypercapnia, Boom scenario, partially and complete food recovery drills it became apparent how we transformed the basic Evolution Rebreather into a stable cave diving platform getting Paul ready to receive his Rebreather cave diver training program.

The ccr cave diver program where taught and supported out of ProTec Playa . The following ccr trimix diver training program where taught and supported out of ProTec Tulum.

Stay tuned for Part II

May 21, 2012   1 Comment