PHYSICS of ROWING
Understanding the basic physic concepts in rowing

Phys120 Term Paper

PHYSICS BEHIND ROWING
Rowing is one of the oldest sports in the world history. Though, rowing has deeper history since oared vessels had been used for transportation, fishing, warfare etc. It is principally all about finding out using the oars to move forward the boats in water. Then, rowing naturally becomes a sport in course of time, with the desire of competition. Which brings the question; what makes the boat go faster? This question carried the science an important part of rowing’s sportive development. We now all know that physics has a big role in sports; and understanding how physics is applied in sports improves the athlete’s performance and develops new techniques. With the time, new experiences, new records make people search and study harder in applied physic to reach best results in sports. Newton’s laws of motion help us to understand mechanics of rowing better. In this paper, some of the physics concepts will be studied in the process of rowing.
The stroke
A rowing stroke has four steps; catch, drive, finish and recovery. These are the most important elements for the efficient rowing.
The catch is the beginning of the stroke; when the blade meets the water a stroke starts. Starting with the first catch, boat accelerates and starts moving forward. As the boat moves forward, the drag force is going to slow down the boat. When the acceleration reaches down to zero, rower should put the blade into water again with an angle through the direction toward movement to prevent sudden break effect that the blade could create. If the rower starts the second catch early and puts the blade into water, the intended speed cannot be reached.
Second step, drive, occurs while the blades are inside the water. The blades that went into water with an angle should be switched to 90 degrees as soon as possible to get the maximum water resistance. When the force that applied to the blades are over resistance force, boat starts accelerating again. This resistance moves the boat forward. The stronger and powerful driving means faster movement. This means more effort and more jobs that need to be done.
At the third step, finish, when the rower reaches his layback position moves the blade out of the water. Again, rower must turn the blades horizontally to avoid the air resistance. The less area means less air resistance which prevents loss of velocity.
When the third step ends, recovery steps starts and the rower takes the first position back and continues the sculling. This circle continuous over and over.
We can already see that rowing is all about balance, velocity and inertia. Propulsion Propulsion is basically pushing an object forward. Rowing propulsion is the same thing that how fishes move inside the water. Fishes oscillate their fins horizontally to the direction of their travels. In the rowing the rules are fundamentally same. A rowing boat or a shell moves forward basically the force that is given by the rower with the oars. Sculling, when the oarsmen places the blades in the water and pulls them, creates the momentum. The resistance of the water has contrary force against the blades that moves the shell forward. This is a result of Newton’s third laws of Motion; every action has an equal and opposite reaction. In rowing, water resistance is the reaction against to the rowing stroke. Therefore, boat moves forward in order to conserve momentum. This plain physic concept is also simple principle of rowing.
Drag Force on the Boat Fluid resistance, also called drag force is the resisting force that acts on a rowing boat while it is moving. Fluid resistance is softer then dry friction but more resilient then air resistance. In rowing, boats surfaces get drag force which has a significant role to decrease the boats velocity in the water. Without thrusts, a hall already in move, will slow down and eventually stay dead on the water by drag force unless any other forces applied to the boat. Thus, speed would be finally zero at the end of the movement. This loss of velocity occurs because of transfer of momentum to the water. Consequently, the faster boat runs across the greater drag force against the boat, in opposite direction. Like the other sports, drag power has a big role in rowing. New materials are being developed and being produced in order to carry the drag coefficient as minimum as it can be. Center of Mass, Buoyancy and Balance Gravity acts as if total mass of the boat is one unit, at a single point although a rowing boat has its own mass plus crew’s mass which 80% of the total mass. Buoyancy, on the other hand, acts at same point, but upward direction. Since the rowers are sitting on the sliding seats in the boat, center of mass changes every time they stroke. Even though oars are not inside the water, when the crew finishes the stroke, crew’s back movement on the sliding seat gives more acceleration to the boat. Conversely, that is preventing the stability of the boat. Movement makes the boat more stable. Also, if the shell is wide bottomed the boat will be more stable. However, wider surface area increases the drag force which makes the boat gradual. Also, it is important that the rowers are sitting above the water level in the boat with a shallower curve. That is why most racing boats have narrow and shallow bottom. Rowing boats are more stable when they are moving as well. Conservation of the Energy As it was mentioned before, the reason a boat moves forward is stroking; the water displacement made by the rower with the oars. This is the transfer of momentum. This represents the work that performed by the oarsmen. Kinetic energy is the energy of motion. When the rower is done with his/her stroke means a work is done on the water. Then the boat accelerates and gains velocity. The kinetic energy that comes from the rower is being transferred to water with momentum. That is where the rowers’ strength becomes an important matter in order to move the boat faster. The greater force, which is given by the rower, will push the water faster, so the boat as a reaction will move more rapidly as well. Having said that, all the rowers do is displacing the water to move the boat further. Even though it was mentioned that the harder the rower sculls, the faster a boat goes; the larger amount water but slower displacement is more efficient than fewer amounts of water but faster displacing. In conclusion, rowing seems an easy sport branch, but there are more dynamics when we think about a faster boat. Synchronization of the team members is also important. Otherwise they will be cutting their speed down and making no efficient process. Another fact is the water condition; a wavy or rough river could make rowing impossible. This also creates another sport branch however in that case, we still would be talking about more or less but same physics concepts. Water temperature also could change the drag force. Cold water will be more viscous. This causes more friction which means more resistance against the hull. Also it is well known that shallow waters have more drag force. The team members’ weight is also another factor on moving fast. The oar’s shape and size also counts. The wider blade displaces bigger amount of water in a stroke, which means more propulsion, in other words faster movement. Length is important too in order to control and balance the boat. A heavier boat sinks deeper which causes larger wet surface as well as more drag resistance. The lighter boat moves faster than a heavier boat if the forces that are applied the boats are the same. A stronger and faster rower thrusts has more powerful strokes, and then the boat moves faster. The length of the stroke is also important. The longer stroke means more powerful one. Briefly, friction, drag, water resistance, buoyancy, propulsion, balance are the physics concepts in behind the rowing. As it was mentioned before, power is the most important factor in rowing. The amount of the force, when the rower applies in the drive phase in stroking, will determine the winners in the competitions. The forces that applied on the oar will determine the velocity of the boat.