Analysis of a Vertical Pin Fatality

posted October 15, 2013
by Charlie Walbridge

article photo 2

On Arch 9, 2013 Dr. Jim McComb died after his kayak pinned vertically on a small ledge on Arizona's East Verde River. His friend Dr. Bill Langhoffer recently forwarded a detailed description of the pin along with several photos. This may be useful to any paddler running difficult whitewater. His detailed accident report can be found in the accident database.

The Anatomy of a Fatal Pin by Dr. Bill Langhofer

River: The East Verde River Wilderness Section through Mazatzal Wilderness. Class 4 on the East Verde (16 miles) and Class 3 on the main Verde (29 miles).  Character of the river is willow tree and tamarisk forest class 4 tree dodging with 3 gorges of class 4 bedrock rapids on the East Verde.  Following the East Verde is a class 3 paddleout for 29 miles on the larger flowing Verde river.

-Flow on March 9th was 500 CFS on East Verde, normally flows 15-20 CFS

-Width of East Verde River ranges from 10 to 100 feet wide.

- Fewer than 20 people have ever kayaked this section of river. Kayaking this section requires a 2 day excursion; therefore boats were loaded with overnight gear. The 5 whitewater boaters kayaking together on this day had a combined 60 years of experience.

Boat involved in pin: Dagger Freefall - Length- 9’ 6” - The boat did not collapse and had no signs of damage.

Paddler that was pinned: Dr. Jim McComb, 64 years old 26 years experience paddling class 4-5 whitewater in Arizona, California, Colorado, Idaho, Utah, and New Mexico. He had paddled this section of river 15 years previously. His other Arizona first descents: Upper Tonto Creek, Tonto Creek Hellsgate Section, Upper Burro Creek, Black Canyon, Lower Sycamore Creek. 

Factors that possibly influenced the pin:

- The longer length of the boat did not allow it to clear the fall once it hit the piton rock.

-  Older style river boats have less rocker, and do not deflect as well when hitting a piton rock.

-  Weight of the boat- with overnight gear the boat was very heavy and settled into the piton rock easier instead of bouncing off.

-  Slow speed off the drop with no boof stroke, prevented him from clearing the piton rock.

-  Chocolate Milk colored water of the South West.  The poor visibility of the water made rescue difficult as we were unsure where and what he was pinned on in the waterfall.  The poor visibility of the water covering the piton rock made it appear like a wave.

-  The river left slant of the waterfall naturally twisted the boat into the slot between 2 rocks on the left side of the fall, making the pin fatal and rescue impossible.

-   On southwest wilderness creeks and rivers, very few people have boated them; therefore, many of the hazards that are well known on the East Coast have not yet been discovered on our rivers.

At the beginning of the third gorge a waterfall that is approximately 7-8 feet in height, at 500 CFS, was noted by the lead boater Ryan who boat scouted the drop.  I was the sweeping kayaker and paddled to river right above the drop and got out to check for wood.  The lead boater and the following 2 boaters paddled over the drop with speed and boof strokes taken on the edge with clean lines angling right toward the middle of drop as they went off the fall. 

The Pin:

1. Jim paddled slowly to the edge and went over the drop leaning slightly forward. 

2. His boat (the bow) hit a piton rock (that appeared to be a wave) at the bottom of the drop, stopping his boat. 

3. His stern settled into the top of the waterfall as water started pouring over the stern.  The water pouring over the stern pushed his torsoforward, pinning him to the bow of the boat. 

4. Once vertically pinned the stern was pushed underneath the water down to the base of the fall, where the natural slope of the rock rotated the boat sideways to the left.

5. Jim pinned in his boat, rotated left into a small slot between 2 rocks on the left side of the fall. 

Jim was now pinned by the piton rock in front of his boat, the waterfall in back, 30,000 pounds per second of water on top (1/2 water flow at 500 cfs), and his body was trapped in a slot between 2 rocks, pinning him in his boat and causing his demise.

Second Photo Caption:

This photo was taken from the river right side where I was standing, while attempting rescue.   In this photo the boat has been removed from the drop.

The tape measure in my left handshows the length of the boat and the approximately 90 degree angle that the boat initially hit the piton rock.  (Piton rock was the smaller rock at a sharp angle)

The slot that his body rotated into can be seen in this photo between the 2 rocks.  Note the sunlight shining through the slot.

The approximate water line at 500 cfs is drawn into the photo.

When attempting rescue, Ryan was standing on the black rock above the piton rock.  If Ryan had fallen off his rock he would have fallen into a sieve.

 

 

Charles Walbridge
Bruceton Mills, WV