Research & Design
My research can be roughly divided into several basic themes. My Biomedical research has been ongoing from more that 20 years and has included a large number of diverse projects. A selection of these would include, halo pin mechanics and MRI compatibility; bone plate modelling and biomechanics, joint reconstruction, soft tissue testing, hard tissue biomechanics and cardiovascular research. I have also worked in the area of assistive devices and equipment design.
My research focus as seen a shift towards activity biomechanics. In particular, I am currently exploring waterskiing biomechanics and canoe paddle mechanics. In both of these research programs, my aim is to improve the accessibility of the sports for all people and in particular our aging population through a better understanding and optimization of the science behind the equipment.
Paddle Research
My research program investigating canoe paddle performance was initiated in the summer of 2010. Its focus is to improve paddling efficiency and accessibility by critically and scientifically examining the design and function of paddles.
The canoe is recognized the world over as an iconic image of Canada with a history interwoven throughout our own. Beginning thousands of years ago as a way of life for the aboriginal peoples the canoe is now primarily a pastime pursuit for millions of Canadians. In its simplest form, canoeing involves not only a canoe, but must also include a paddler and their paddle. In this trio, it is the paddle that has undoubtedly received the least scientific attention where there is a void in our understanding of paddle history, design and function. In fact a review of the relevant literature shows an almost compete lack of historical and related scientific reference material.
This research program is the first of its kind. It will allow us, as a nation, to re-evaluate the achievements of our Aboriginal peoples and the technology they developed and employed over thousands of years. Our results will form the basis of a new perspective on the paddles held in the Canadian Canoe Museum. These same results will provide a new insight into the complex interaction between paddle and water and will allow a new level of scientifically based optimization to occur in paddle design and manufacturing. The proposed program is one with historical, cultural and scientific relevance and its results will improve our understanding of paddling efficiency, and access to the sport of canoeing for generations.
Optimally a paddle will grip the water when required to propel the canoe, and knife cleanly and without unwanted vibration through the water during stroke recovery or steering strokes. A paddle must be strong enough to resist breakage, but light enough to be used for long durations of time. It must be stiff enough to give a good feel of the water but flexible enough to cushion the joints of the paddler. The paddle must be comfortable on the hands and easy on the joints. In an average day of canoeing a paddler may perform up to 15,000 strokes. Any shortcomings in the paddle will be magnified through the repetitive nature of its use. Inefficient or poor paddle design will leave a paddler uncomfortable with blistered or bloody hands, strained joints, unnecessary fatigue and a less than optimal experience.
Paddling does not need to be a painful experience.
This extensive skin damage resulted from four days of paddling with a poorly designed, inexpensive paddle.
Any look into paddle design would be incomplete without an examination of historic aboriginal paddle technology. The aboriginals of North America used paddling as a way of life for approximately 5000 years. With the advent of commercial paddle production in the late nineteenth century, aboriginal paddle design effectively disappeared. Compounding this unfortunate event, historical documentation of the aboriginal paddle designs is also almost completely absent. The reference book by Adney (1964) includes one of our society’s only records of early paddles with line drawings of approximately 15 paddles. These drawings show representative paddle shapes from several regions of North America but only a subset of these drawings have any profile information at all and none could be considered suitable for accurate replication of the paddles. It is a sad fact that thousands of years of aboriginal paddle technology is now effectively extinct.
A review of recent scientific literature shows a similar situation with an almost compete lack of historical and related scientific reference material pertaining to the canoe paddle.
Working in collaboration with the Canadian Canoe Museum and Redtail Paddles of Hastings, Ontario, the first stage of this research program was initiated in the summer of 2010. Our paddle research began with the characterization of historically relevant archival paddles at the Canadian Canoe Museum, and both lab and water testing of a selection of commercially available and custom made paddles.
The paddles available through the museum were subjected to a number of measurements to record their mechanical characteristics including: mass, natural frequency, centre of mass position, resonance patterns, resonance node positions, material, cross section profiles and overall dimensions. The goal of this work was to generate the information required to reproduce, as accurately as possible, a set of historical paddles that could then be subjected to physical experimental analysis. The same measurements were also conducted on our set of commercially available paddles.
The commercially available paddles were also subjected to a water-based experiment to determine their propensity to vibrate while slicing through the water. This experiment was conducted to begin our experimental analysis of paddle performance. Vibration in general is an unwanted characteristic in a paddle and is generated by the interrelationship of vortexes being shed from the blade and the natural resonance of the paddle structure. The induced vibrations then cause fluid drag on the paddle to rise by a factor of up to 3 (Blevins, 1995). This drag is unwanted. In this experiment, paddles were knifed through static lake water using an outboard powered boat at speeds ranging from 0 to 4.5 m/s. A pair of tri-axial accelerometers were mounted on the shafts of the paddles. These accelerometers were used to measure translational and rotational vibration in the paddles as a function of paddle velocity. The accompanying figure shows a typical paddle response to knifing through the water.
Canoe velocities can commonly reach 1.5 m/s. Underwater paddle recovery manoeuvres require the paddle blade to be drawn through the water against this flow. Relative paddle fluid velocities of up to 3 m/s are not unexpected. In this situation, vibration and the associated paddle drag, work against the progress of the canoe and reduce the overall efficiency. A large subset of our tested paddles vibrated at velocities below 3 m/s and all of the paddles tested displayed varying degrees of rotational vibration. Additional low frequency resonance was also observed in some of the paddles. Full results of this testing are still being analysed but indicate that minor changes in blade shape, cross section and translational and rotational natural frequencies can have a dramatic effect on propensity for vibration and overall hydrodynamic performance.
In examining the literature it is clear that research into the relationship between structural vibrations and fluid flow has remained primarily in the experimental realm. Within these studies, typically cylinders and foils have received the greatest amount of attention. A paddle blade, while effectively a symmetrical foil in cross section, also has the additional complexity of varying shape and fluid velocities along its length. I believe that future application of the more advanced techniques developed for foils will allow the flow characteristics around and in the wake of paddle blades to be better understood and then optimized to improve paddle performance.
Research Program Objectives – Long Term:
The long term goal of this research program is to improve the accessibility of canoeing to our entire population. Improved canoe efficiency through better paddles will allow individuals to participate in the sport for greater periods of time and later into life, thereby increasing their overall activity levels and fitness. My approach to accomplishing this is to bring scientific and engineering analysis to the design and optimization of canoe paddles.
Water Skiing Research
Water skiing is a sport that approximately 10 million North Americans participate in annually. Since the first skiers took to the water in 1922 it has developed into a multimillion dollar international sport.
Looking at the current technology of water skiing equipment, it isn’t hard to trace its roots. Ralph Samuelson successfully skied on Lake Pepin in Lake City, MN in 1922. He was the first recorded person to water ski. His skis consisted of two pine boards with leather bindings. From this modest beginning came the old style flat bottomed skis that were standard for decades. The 1960’s were a time of many changes and water skiing was no exception. Affordable high performance boats became readily available, fueling the sport. With this increased power and speed came the demand for skis with improved performance. Manufacturers rose to the challenge, developing the features commonly associated with today’s best slalom skis including: high wrap bindings, concave bottoms, drop through fins and beveled edges.
One company in particular was to become well known for its innovative ski designs. Maherajah Water Skis began producing skis in the early 1950’s and was the source of many of the currently employed design features associated with the best skis. Their pioneering work on ski design lead to a series of national and world championship ski titles in the 1970s’s and later. Working in collaboration with Maharajah Water Skis we initiated our water ski research looking at the performance characteristics of the Maherajah Fastback slalom ski an comparing it to more typical slalom skis on the market.
Our recent work has been in collaboration with Connelly Skis and Lighthouse Lake Water Sports Centre near Bancroft. This research has been looking at the performance characteristics of the skis comprising the Connelly slalom ski line. See the 2009 and 2010 updates and the results accepted for publication for more information.
Typical rope load (solid line) and boat velocity (dotted line)
for a slalom ski water start, run and cutting as collected during our 2009 testing session.
Cardiovascular Research
Investigators:
- J Runciman
- L Arroyo, OVC - Department Clinical Studies
- L. Viel, OVC - Department of Clinical Studies
- A. Valverde, OVC - Department of Clinical Studies
Students:
- M. Teeter, J. Bakker, L. Patrick and I. Whatley
Approximately 80% of racehorses can be expected to develop Exercise-Induced Pulmonary Haemorrhage (EIPH) during their career. The management and treatment of EIPH have a substantial economic impact to the equine industry, with the cost of treating EIPH estimated to exceed $100 million annually in the United States alone.
There is currently a poor understanding regarding the cause of EIPH and potential mechanisms include capillary stress failure, pulmonary fibrosis, and small airway disease. Currently, the most accepted cause for EIPH is exercise-induced pulmonary hypertension, resulting in pulmonary capillary rupture.
A horse suffering from Exercise Induced
Pulmonary Haemorrhage (EIPH).
Recently we observed the presence of calcification and fibrosis of the pulmonary artery wall in a large proportion of racehorses. Such lesions are known to interfere with elasticity that the vessel needs in order to accommodate the cardiovascular pumping action of the heart during strenuous exercise. Indeed, arterial calcification is the most important cause of vascular stiffness in humans and is considered a predictive factor for cardiovascular mortality, coronary morbidity and fatal stroke.
Similarly, we suspect that the compliance of the pulmonary arterial wall of horses with artery calcification is affected. This impaired compliance will directly affect the capacity of the vessel to deal with large fluctuations in blood pressure, which may in turn cause the downstream microvasculature damage seen with EIPH.
We hypothesize that the pulmonary artery compliance of horses with calcified arteries is impaired. Our research previous research examined the relationship between pulmonary vessel loading and calcification. Our current study is examining pulmonary artery relative stiffness and its impact on blood flow characteristics.