Minimum Water Depths for Head First Diving From Pool Decks, Starting Blocks, Docks and Similar Low Fixed Platforms

Introduction:

The primary objective of Part 6 of the New York State Sanitary Code is to assure that public bathing facilities are operated in a safe and sanitary manner.

To accomplish the safety objective, the code specifies minimum water depths for head first diving from pool decks and minimum depths for new installations of starting blocks.

This fact sheet reviews current research, studies and includes some of their recommendations regarding diving from low fixed platforms, such as pool decks, starting blocks and docks in order to prevent the potential for serious injury.

Mechanism of Injury:

Spinal cord injuries occur when the diver strikes his/her head on an object such as a pool or lake bottom or a submerged object. Most serious injuries involve the cervical spine (neck) in the C-5 region and are classified as compression or flexion-compression injuries.

A diver's extended hands and arms provide the only source of protection to the head. Should the arms collapse upon impact or not be in a forward position, the head is vulnerable. Minimal force is needed to cause spinal injury especially when the neck is not in a neutral position. Most diving injuries occur with the neck in the flexed (chin toward chest) position. The diver's weight, underwater velocity and angle of impact are major determining factors on whether impact will result in injury. The heavier the individual and the greater the velocity the more likely injury will occur. Therefore, young (small) children are generally not subject to the increased level of risk as adults.

Physics of Diving:

A head first dive from a deck or starting block is comprised of several components which include: the diver's starting position; use of legs and arms which generate thrust; in-air trajectory; entrance angle in water; in-water trajectory; and the arm and head position in the water.

It should be noted that a running head first dive from the deck can result in entrance velocities similar to those resulting from take-off from a one meter diving board and can project the diver further out into the pool.

When diving into shallow water very little reaction time is available between entering the water and striking the bottom. To avoid injury it is critical that the diver's arms and hands are locked forward in a proper position that prevents head contact with he bottom and the diver must steer-up immediately by arching the back, lifting the head and aiming the hands up.

Diving Injury Epidemiology:

It is estimated that approximately 800 spinal cord injuries resulting from diving into a body of water occur each year in the United States.¹ Approximately ¾ occur in the natural aquatic environment (lakes, ponds, streams, etc.) while the remaining amount occur in swimming pools. It is estimated that ninety percent of these incidents occur in water depths less than 6 feet .^1,2

A review of incidents reported by local health departments to the BCSFP occurring at regulated bathing facilities in New York State from 1987-1991 indicates 30 shallow diving related injuries occurred; 15 resulted from dives in the shallow end of pools; 8 occurred at beaches; 7 resulted from starting block use (all were competitive swimmers during competition or team practice).

Diving Safety Recommendations:

• The American Red Cross recommends a minimum of 9 feet of water depth for head first dives including dives from pool decks.³
• Results for a comprehensive study of diving injuries are presented in "Diving Injuries: The Etiology of 486 Case Studies with Recommendations for Needed Action" edited by Dr. Alexander Gabrielsen, Ph.D., 1990, NOVA University Press.¹ A 13 member editorial panel of aquatic experts recommended:
  • Posting of appropriate warning signs which includes prohibition of diving in water depths less than 5 feet.
  • Proper supervision to control activities of swimmers/divers.
  • Public education in swimming and diving.
  • Improved regulations and standards for pool and beaches addressing design and operation issues.
• A study of spinal cord injuries to starting blocks entitled "Starting Blocks the Etiology of 30 Spinal Cord Injuries as a Result of Dives Made from Starting Blocks with Recommendation" by Dr. Alexander Gabrielsen, Ph.D., and Stanely M. Shulman, M.A., Feb. 1992, ⁴ recommends the following:
  • Move all starting blocks now located in shallow end of pools to the deep end (greater than 6 feet of water).
    
  • Eliminate use of blocks and start all competitive swimming races from the pool deck, if relocation to the deep end is not possible.
• The National Swimming Pool Foundation (NSPF) sponsored diving research and produced a brochure in 1985 based on the results which includes numerous diving safety recommendations including:
  • Don't dive into shallow end of pools.
  • Don't run and dive.
  • Don't dive from starting blocks unless under direct supervision of a qualified coach.
  • Know how to control your dive path and steer up.

Department of Health Requirements:

• Prohibits head first diving in water depths less than 8 feet.
• Restricts use of starting blocks to competitive swimmers or swimmer training activities.
• Requires new installation (effective October 7, 1992) of starting blocks to be in the deep end in at least 6 feet of water.
• Requires every facility to develop and implement a bathing facility safety plan which must address injury prevention activities which should include diving safety.

References:

1. Diving Injuries: The Etiology of 486 Case Studies with Recommendations for Needed Actions. M. Alexander Gabrielsen, Ph.D. 1990.
2. Diving Safety in Swimming Pools. A Report to the National Swimming Pool Foundation. Richard Stone. 1980.
3. American Red Cross Basic Water Safety, Washington, D.C., 1988.
4. Starting Blocks: The Etiology of 30 Spinal Cord Injuries As a Result of Dives Made form Starting Blocks with Recommendations. M. Alexander Gabrielsen, Ph.D., and Stanley M. Shulman, MA, Feb. 1992