Modeling the Risk of a Propeller Striking a Person or a Submerged Object: a Senior Design Project

Recreational boat propellers often strike swimmers, divers, snorkelers, tubers, people ejected from the boat, logs, driftwood, dredge pipes, debris, marine life, or other floating or submerged objects. A model of those risks would be useful in crafting:

  • Boating safety tips
  • Regulations
  • Propeller safety products
  • Design and marking of swimming, snorkeling, and diving areas
  • Boat and boat entry and exit design
  • The place of alcohol, life jackets, and boating safety training
  • Boat designs

We encourage college math and engineering students looking for a senior design project, capstone project, senior thesis, masters thesis, or similar project to consider modeling the risk or probability of a propeller strike in a given area.

We first saw some work in this field several years ago from NASA. They modeled the probability of spacecraft encountering orbital debris based on debris spatial density, flux, etc. See the ORDEM2000 Orbital Debris Engineering Models.

Quite recently we saw an iceberg model that might be able to be adjusted to represent people in the water. Description of Iceberg Probability between Baffin Bay and the Grand Banks using a Stochastic Model. Ebbesmeyer, Okubo, and Helseth. Deep Sea Research Part A. Oceanographic Research Papers. Vol.27. No.12. December 1980. Pgs. 975-986.

Authors of the iceberg paper model iceberg counts as a random sequence that is exponentially distributed.

Models of the number of people in the water and number of boats in the water would need to be time, weekday, and holiday adjusted. Some debris models might need to be seasonally or storm adjusted. Boat types would need to be addressed by population counts.

U.S. Coast Guard Boating Accident Report (BARD) data might be helpful, as well as the Coast Guard National Recreational Boating Safety Survey

With so many variables the subject would probably have to be addressed in segments, such as beginning with modeling the risk of propeller strikes on a certain area of a theoretical lake during on a summer day.

We found a few other other areas that might provide some useful background information.

  • Wildlife-strike Prevention – The System Safety Approach. This Transport Canada paper talks about managing aircraft bird strikes by focusing on reducing exposure, reducing probability, and reducing severity. That same approach could be applied to boat propeller safety.
  • Bird Strike Risk Assessment for Athens International Airport by Anagnostopoulos.
  • Papers on modeling the probability or risk of wildlife strikes:
    • Aviation bird strikes
    • Moose collisions with vehicles
    • Deer hit by automobiles
    • Windmill / wind tubine strikes by birds
    • Building strikes by birds
    • Highline / Utility line strikes by birds
  • Hamer Risk of Collision Model – Avian Risk of Collision Model by Hamer Environmental.
  • Roadway intersection video studies counting number of times vehicles cross at right angles to each other within a fraction of a second (near collision).
  • Studies of midair aircraft collisions
  • Studies of typical boat trajectories (how boats move around in typical waters) such as:
    • Autonomous Mission Planning and Execution for Unmanned Surface Vehicles in Compliance with the Marine Rules of the Road. James Colito. Masters of Science thesis in Aeronautics and Astronautics. University of Washington. 2007. This converts marine rules of the road decisions to logic for controlling unmanned vessels.
    • Comparison of Simplifying Line Algorithms for Recreational Boating Trajectory Dedensification. Pelot and Wu. Geomatics Solutions for Disaster Management. 2007. Pgs. 321-224.
    • Classification of Recreational Boat Types Based on Trajectory Patterns. Pelot and Wu. Pattern Recognition Letters. Vol.28. No.15. 1 November 2007. Pgs. 1987-1994. Available on Science Direct.
    • Location-Based Risk Analysis of Recreational Boating Activity. Pelot, Delbridge, Wu, Hilliard, and Wootton. Maritime Activity & Risk Investigation Network. March 2006.
    • Characterizing Recreational Boating Patterns Based on GPS Trajectory Points. Wu. Phd Thesis. Dalhousie University. 2007.
    • Boating spatial analysis papers
    • Boat crowding papers.
    • Aerial counts of crowds and aerial boat count papers.
  • Studies of fish being struck by propellers (fish strike counts)

We can envision an accompanying Propeller Risk Assessment example similar to “Bird Strike Risk Assessment for Athens International Airport” by Anagnostopoulos. He identifies the levels of data required for a Bird Strike Risk Assessment in the chart below.

Bird Strike Risk Assessment chart

Bird Strike Risk Assessment chart

The chart above could be modified to represent the levels of data required to perform a Propeller Strike Risk Assessment from information in the Propeller Accident Risk Worksheet accompanying our Developing a Consumer Guide to Selecting Propeller Guards post.

It would also be nice if the results could also be presented in a poster format similar to this bird wind turbine project, A Simulation Model for Assessing Bird – Wind Turbine Collision Risk. Nations and Erickson. West, Inc.

The Bird Strike papers are interesting. Birds being struck by planes are a nice analogy to people being struck by boats (propellers). Several thrusts to prevent bird strikes focus on keeping birds and planes as far apart as possible. With boats that becomes difficult, even in you only focus on people in the water near boats (skiers, tubers, swimmers, floaters).

One tack the boating industry has not identified, is to make being in the boat so much fun that fewer people will chose to exit it to the water. More on water activities, excitement, and chances to get wet while still in the boat would keep some people in the boat, reducing their risk to being struck by a propeller. Even creating new publicly accepted ways to urinate in or from a boat without getting into the water might prevent some propeller injuries. Creating separate areas for PWCs, expanding cable skiing, seeing if cable park towed tubing is feasible and fun are other possible ways to separate people in the water from boats. Docking and launching of boats from a boat ramp might be made more secure (less chance of someone ending up in the water) by minor changes in boat, boat ramp, boat trailer, tow vehicles, or dock designs. These ideas were quickly generated by thinking about the parallels to bird strikes (separate people in the water from boats as far as possible).

A full analysis of risk and how the many variables play into the overall probability of a propeller strike in a given area should provide other insights into potential ways to improve boat propeller safety.

Once a model was constructed, it could serve as a base for additional future projects including modeling risk of striking logs, driftwood, dredge pipe, debris, marine life or other floating or submerged objects.

If you are interested in pursing this topic as a Senior Design Project, Capstone Project, Senior Thesis, Masters Thesis or similar project, please contact us.

As always, if anybody, firm, or organization is interested in sponsoring or partially sponsoring this project through the donation of funds, equipment, mentoring, facilities, data, etc. please contact us. Sponsorship is the fastest way to make these projects more attractive to potential student researchers.


  • An Index of Risk of Co-Occurrence Between Marine Mammals and Watercraft: Example of the Florida Manatee. Sarah Bauduin, Julien Martin, Holly Edwards, Oliver Gimenez, Stacie Koslovsky, and Daniel Fagan. Biological Conservation. Vol.159. (2013) Pgs.127-136. They use statistical models to estimate the risk of manatee boat strikes for specific places. Models include the challenges of correctly estimating manatee distribution, changing patterns based on seasons, weather, and local environmental issues. We found this reference in March 2013, several months after we wrote this post.

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