Physics in Sailing and Modern Boating (High School)

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The History of Sailing

Just over two thirds of the Earths surface is covered by water. The majority of the human

population lives close to the shore. Since the start of humanity, man has always been confined by thesea. This report is not solely based on the history of sailing, but rather is the history of people who

pushed the worlds horizon.

For thousands and thousands of years, wind was the ONLY source of energy that could allow

man to travel long distances over seas. Distances which were far too long to be fueled by man-power.

Because of this limitation, it led to many different civilizations attempting to use the winds energy their

advantage.

Lets start from the oldest and most basic of vessels. These vessels were simply semi-carved trees with a

piece of cloth on top- still used by some fishermen in developing countries which allowed people toquickly improve their skills in navigation and the construction of more sophisticated boats.

Sailing was Key to Mediterranean Civilizations.

More highly developed civilizations formed around the Mediterranean Sea, therefore creating a

strong interest in navigation and all of the sciences associated with it astronomy, meteorology,

shipbuilding and even basic forms of oceanography.

Much of the Phoenician, Egyptian, Roman and Greek ideas / ideology disappeared and was

forgotten during the middle Ages. Viking longboats used mostly the power of men at oars and

primitive square-sails. The shape of square-sail rigs quickly became the most common rig type in

European nations.

Figure 1) a model of a Viking Longboat.



The Arabs, however, developed their own characteristic, triangular sail as a more efficient solution to

aquatic navigation. Arabs could sail upwind very well and proved to be more flexible and navigable than

European ships equipped with square-sails. Many aspects of this sail are still used today.

Chinese Sail Boats

The Chinese lugsail (sailboat) is more often referred to as a junk rig, which was rigged to ashort mast and based on long bamboo battens. The construction of junks was likely to be the most

efficient and sophisticated of its days, being cheap and flexible and at the same time easy to navigate.

This allowed junks to sail with a relatively small crew on board, ideal for use on rice plantations.

Figure 2) a modern day Chinese junk rig

As the leading seafaring nations changed over the course of centuries the materials remained

essentially the same. Wood was cut into shape or tied together and only very rarely other materials

were used for the construction of the main body of ships. This should change with the up rise of Britain

after the defeat of the Spanish Armada.

The Industrial Revolution leads to the evolution of sailing

After the industrial revolution, new materials for the construction of sailing vessels becameeasily accessible. Also, distances became longer as the British reached out over the oceans built global

empire. The new needs and opportunities led to a boost in innovative designs and developments in

nearly every aspect of society, however, it was still wind that would transport most goods now over

thousands of miles of canals that cut Britain into navigable parts.

Offshore, large sailing ships dominated the oceans. Among the most legendary cargo-carrying

ships of that period were windjammers and clipper ships (see graphics below). The latter ones were

most likely called that way as they allowed trade companies to clip short the time for individual

passages, as they were designed to speed up the traffic between the British mother island and its

outposts in India, Australia or the Americas.



Figure 3) a modern day windjammer

Figure 4) a restored 19th century clipper ship

Sailing for pleasure

In the 16th and 17th century, the oldest indications for a new trend emerge: sailing out of

pleasure rather than transportation, exploration or warfare.

In the Netherlands-at that time it is fair to consider them a trading empire- a trading empire that

spun the Worlds seas; Europes largest fleet maintained a flourishing economy. The rising prosperity of

Dutch merchants and their strong orientation towards maritime activities most likely caused them to

start sailing as a method of entertainment.

Small sailboats that were light and easy to navigate soon emerged and were called Jaghts. The

modern English word Yacht is derived from that and the first Dutch yacht arrived in England in 1660 as



a gift to King Charles I. The design stimulated a whole new approach to sailing in Britain In 1661, two

more yachts had been built: Catherine, a second yacht to King Charles, and Anne for the Kings

brother. With these two vessels, the King and his brother raced between Greenwich and Gravesend and

back along the Thames and thereby, doing the first pleasure sailing race in history.

Figure 5) the nautical yacht flag. This particular flag indicates that the vessel is a non commercial American recreational

vessel.

The first half of the 20th century was the peak age of yachting as a luxury sport for wealthy

people. It was probably also the peak of yacht design and the development of a particular nautical stylethat is still unraveled by modern designs. In the second half of the 20th century, yachts once again

underwent a dramatic revolution due to the use of new materials. The use of plywood, (and a bit later

on fiberglass) had a tremendous impact on boat designs and lead to the development of dinghies that

were lighter and still stronger than any sailing vessels before. This also meant that the construction of

yachting boats became easier and thereby, cheaper. This made the whole sport more accessible and

triggered a diversification of styles and shapes.

Figure 6) (Right ) a modern day sail dinghy.

Figure 7) (Left) a modern day motorized dinghy



Dinghy sailing grew especially in the 1960s. Constantly, boat builders launched new designs. Building

boats at home became a passion to many people, and alongside with the big, established yacht builders,

more and more small firms arose and found their niches on the growing market. With an increasing

number of people being interested in sailing, the number of clubs, races and cruises all over the world

grew rapidly as well.

The late 1960s saw the rise of fiberglass as an even more flexible and reliable boat-building material.Carbon-based and other modern materials still lead to exciting new designs and innovations in the

construction of dinghy sailing boats up to today, setting new records in speed, weight and even,

reliability.

From being a luxury to becoming a sport

Cruiser racing proved to be very popular. Since these days, more and more professionals

compete for the most prestigious trophies, and only private cruiser races are suitable for spare-time

sailors from the club-level. This led to a forking between sailing as a competitive sport and the

traditional pleasure yachting. Both areas still gain popularity from year to year. There are more

professional, competitive sailors than ever before and the sport attracts a lot of attention with major

events being followed by hundreds of thousands of sailing enthusiasts all over the World. On the other

hand, sailing yourself for joy has never been easier or more affordable.

Despite of common stereotypes of sailing as being exclusive or a non-affordable luxury, today more and

more people discover their passion for this sport. Sailing communities in all countries offer opportunities

to get involved with the sport on any level of interest from a completely passive one by doing a cruise

with a professional crew, to active sailing as a boat owner. Sailing has never been more popular than it is

today and seems to go into a bright future, providing the liberals dont screw around with it



The Motion of SailingThe term sailing often infers the use of a sailboat. But by its nautical definition it is defined as the sportof operating or riding in boat. Therefore, this section will describe motion in various types of vessels.

Vehicles in water are moved by a) energy from humans b) wind-energy c) energy from the engine,

hydrofoils and hovercrafts

Figure 8

Boats a) boats are moved with oars b) when water is pushed backwards by oars in a boat, a backward

momentum is produced c) a forward momentum of equal magnitude to the backward momentum is

produced, therefore moving the boat forwards (See Figure 8 above)



Figure 9

Sailing boats/ yachts a) sailing boats and most yachts move by using wind power. These boats have one

or more sails with large surface areas b) when the wind blows, the movement of the wind is blocked by

the sails. The momentum of the wind is transferred to the sails, causing the boat to move forward.

(Figure 9 above)

Figure 10) A diesel powered ship



Figure 11) The USS New York (LPD 21) - A nuclear powered ship

Ships a) large ships use diesel engines or nuclear energy to move their propellers located at the stern(back end) of the ship b) large amounts of water is pushed backwards very quickly by the propellers,

creating a large backward momentum c) a forward momentum that is of equal magnitude to the

backward momentum is produced, causing the ship to move forward. (See figure 10-11 above)

Figure 12 Hydrofoils a) a hydrofoil consists of underwater foils attached to the front and rear of its hull b) when a

hydrofoil moves slowly; it behaves like any other boat. Energy from the diesel, gasoline, or 2 cycle oil-gas

mixture engine rotates the propeller and pushes water backwards. The backward momentum of water

produces a forward momentum that pushes the hydrofoil forward c) When a hydrofoil accelerates to a

higher speed, the flow of water over and around the foil produces an upward force called lift or upthrust



d) this will raise the hydrofoil out of the water. Eventually, most of the hull will be out of the water.

Friction with water is reduced and the hydrofoil can travel much faster. (See diagram 12 above)

Figure 13) The LCAC-27 (USS San Antonio-LPD 17) The first nuclear powered hovercraft

Hovercrafts a) a hovercraft is a vehicle that floats on top of a cushion of air while moving. It canskim across land or water b) a central fan draws in air from the atmosphere and forces it

between the hull and the outer skirt, forming an air cushion c) the air cushion is also used to

produce propulsion. The propulsion is produced by the rotation of propellers or through

propulsive jets e) the backward momentum of water or air produces a forward thrust that

propels the hovercraft. (See figure 13 above).



The Reason there is motion in sailing

Figure 14) the Shape of the Vehicles assists in its Motion in Water

An object moving through the water needs to overcome the drag (resistance) against it. The

larger the surface area of the object that comes into contacts with water, the larger the drag

(resistance) when moving through water. A streamlined-shaped object can travel through

water with the least water resistance or drag because of its reduced surface area. (See diagram

above) The smooth sides and rounded outline of the shape do not disturb the flow of water

and do not cause turbulence behind the object. Turbulence causes drag in a vehicle. The

hulls of vehicles that are submerged in water are streamlined so that the vehicles can sail

faster through the water. The center of gravity of the vehicles in water must be below the

water level so that the vehicle is stable and balanced when moving on water (buoyancy).



Archimedes¶ Principle

Figure 15) Archimedes' Principle

(Note the following paragraph has been copied from: http://scienceray.com please see bibliography for

the complete link) Archimedes Principle states that the pressure in a liquid increases with depth. When

an object immerses in water a) the object does not move sideways because the pressure exerted on

both sides of the object is equal. The depth of both sides of the object is equal b) the bottom surface of

the object is deeper than that of the top surface. The upward pressure exerted on the bottom surface of

the object is greater than the downward pressure exerted on the top surface. The difference in pressureexerted on the object produces a net upward force called the buoyant force or upthrust. The

Archimedes Principle also states that an object, whether completely or partially immersed in a fluid

(liquid or gas), is acted on by an upthrust which is equal to the weight of the displaced fluid. The

principle of floatation states that the weight of an object floating on the surface of a liquid is equal to

the weight of the liquid displaced by the object. There are two forces acting on a submerged object. One

force is the upward buoyant force and the other force is the downward gravitational force or the weight

of the object. An object will a) sink if the weight of the object is greater than the buoyant force b) move

upwards if the buoyant force is greater than its weight c) remain stationary in a liquid or float on the

surface of the liquid if the buoyant force is equal to its weight. See diagram above)

Archimedes Principle in use

A ship floats on the surface of sea water if the upward buoyancy force that it receives is great enough to

overcome the downward force of its weight. A steel ship is hollow inside so that the overall density of

the ship is less than that of sea water. The level a ship sinks in the sea depends on the buoyant force

that acts on it.



The deeper a ship sinks in the sea, the larger the volume of sea water that is displaced. Hence the

buoyant force increases. The density of sea water varies with location. This will vary the level that the

ship sinks in the sea. The denser the sea water, the larger the buoyant force. The ship will submerge

deeper in fresh water than in sea water. The density of sea water varies with the region it is in and the

season it sails (water temperature). That is why; most ships are marked with the Plimsoll line. The

Plimsoll line is painted on ships to show the depth a ship should travel at.



Motion found in sailing (Speed)Determining the average speed of an object:

Background: Average Speed (velocity) is the distance traveled divided by an elapsed time. For instance,

if you travel 100 miles in 2 hours, your average speed would be 50 miles/hour.

Average Speed = DistanceTime

Figure 16

= change in

Here is another way of looking at the formula:

Average Speed = d2 d1

t2 t1 Figure 17

Determining the speed of a boat:

It is important to realize that the speed of watercraft and aircraft are measured in knots.

1 knot = 1 nautical mile per hour = 6076 feet per hour

1 mph =1 mile per hour = 5280 feet per hour

Here are some of the many formulas that are used.

y Top Potential Speed of recreational watercraft with type 3 class r2 outboard engine boats:

Top Potential Boat speed= (Total Shaft Horsepower/Weight)(constant)

y Calculate Boat Speed: If your speed log is disabled, you can calculate the boat's speed by

determining the time it takes for a wood chip or other floating object to pass from the bow tothe stern.

Boat Speed = [ 60(sec/min) X 60 (min/hr) X length of boat in feet ] /[ 6076.1

(feet/nautical mile) X seconds for chip to pass ]

y Hull Speed

Hull Speed = 1.34 * (LWL)1/2

LWL: length of the hull at the waterline.

y Sail Area / Displacement Ratio (SA:D)

SA / D = Sail Area / (Displacement in Cubic Feet )2/3

y Displacement : length ratio (D:L)

D / L = Displacement / ( 0.01 * LWL )3

NOTE: Displacement is in long tons

y Sail Wind Load

Load in Pounds = Sail Area * (Wind Speed)2

* 0.00431

(

(

(



Newtons Laws and Sailing

Newton's three laws of motion - Isaac Newton identified two ways that sails move a vessel

through the water. He described force in the formula: F=ma. Air is quite heavy (dense) at sea

level and following Newton's formula; you can see that accelerating an air mass over the curvedsurface of a sail will increase the force acting on a sailboat.

Figure 18

Isaac also tells us that for every action, there is an equal and opposite reaction. Wind striking a

sail turned across it is deflected and forced in a new direction. This is known as Newtonian lift

and even a flat surface can produce it. If you have ever watched an airplane fly upside down,

this is how it is accomplished.



Bibliography

Graphics:Figure 1: Westbourne Model Centre Model Boat Suppliers Web <http://www.westbourne-model.co.uk/images/Model-Boats/Billings-model-Boats/roar.gif>.Figure 2: Seaworthy Small Ships. 27 Dec. 1999. Web.

<http://www.seaworthysmallships.com/images/junk-button.gif>.Figure 3: Windjammer Cruises in Maine." N orthern N ew England Vacations | N ew England Travel Vacation | Maine, N ew Hampshire, Vermont. Web.<http://www.theheartofnewengland.com/travel-WindjammerCruiseMaine.html>.Figure 4: McDermott, Matthew, New York, and NY. "Slower Shipping Could Reduce GHG Impact: TreeHugger." TreeHugger . N.p., n.d. Web. 26 Dec. 2009.<http://www.treehugger.com/files/2008/06/slower-shipping-ghg-reduction.php>.Figure 5: "Historical & Specialty Flags." Hannah-Lore Flag Co., Beverly, MA 01915. N.p., n.d.Web. 26 Dec. 2009. <http://www.hannah-loreflagco.com/historicalspecialtyflags/>.Figure 6: " Used Boats - New Boats - Search New & Used Boats For Sale - BoatPoint Australia."U sed Boats - N ew Boats - Search N ew & U sed Boats For Sale - BoatPoint Australia. N.p., n.d.Web. 26 Dec. 2009. <http://boatpoint.com.au>.Figure 7: Page, M News Home. "the horse's mouth: ." the horse's mouth. N.p., n.d. Web. 26

Dec.2009. <http://horsesmouth.typepad.com/hm/2007/02/index.html>.Figure 8: Plamer, josh. "The Physics of Sailing." David N ewman's Page. N.p., n.d. Web. 26 Dec.2009.<http://ffden2.phys.uaf.edu/211_fall2002.web.dir/josh_palmer/basic.html>.Figure 9: Plamer, josh. "The Physics of Sailing." David N ewman's Page. N.p., n.d. Web. 26 Dec.2009.<http://ffden2.phys.uaf.edu/211_fall2002.web.dir/josh_palmer/basic.html>.Figure 10: "The Motion of Vehicles in Water | Scienceray." Scienceray | All That is Science,Astronomy, Biology, Chemistry, Mathematics, Physics. N.p., n.d. Web. 26 Dec. 2009.Figure 11: "USS New York (LPD 21) | The Official Website. Commissioning Event Information.."U SS N ew York (LP D 21) | The Official Website. Commissioning Event Information.. N.p., n.d.Web. 26 Dec. 2009. <http://www.ussny.org/>.Figure 12: "Gold Coast Waverunners - Yamaha Waverunner - Why Choose Yamaha?." Gold CoastWaverunners - Yamaha Waverunner - Home. N.p., n.d. Web. 26 Dec. 2009.<http://www.waverunner.com.au/pages/why-choose-yamaha.php>.

Figure 13: Hovercraft - Wikivisual." Main Page - Wikivisual. N.p., n.d. Web. 26 Dec. 2009.<http://en.wikivisual.com/index.php/Hovercraft>.Figure 14: "The Motion of Vehicles in Water | Scienceray." Scienceray | All That is Science,Astronomy, Biology, Chemistry, Mathematics, Physics. N.p., n.d. Web. 26 Dec. 2009.Figure 15: "The Motion of Vehicles in Water | Scienceray." Scienceray | All That is Science,Astronomy, Biology, Chemistry, Mathematics, Physics. N.p., n.d. Web. 26 Dec. 2009.Figure 16: Mullen, Jonathan. "Physics in Sports." Physics in sports-A modified web-quest.Jonathan Mullen. 26 Dec. 2009.Figure 17: Mullen, Jonathan. "Physics in Sports." Physics in sports-A modified web-quest.Jonathan Mullen. 26 Dec. 2009.Figure 18: Conger, Cristen. "HowStuffWorks "The Physics of Lift"." Howstuffworks "Adventure" .N.p., n.d. Web. 26 Dec. 2009. <http://adventure.howstuffworks.com/outdoor-activities/water-sports/sailboat4.htm>.

Report Data:

y "The Motion of Vehicles in Water | Scienceray." Scienceray | All That is Science, Astronomy,Biology, Chemistry, Mathematics, Physics. N.p., n.d. Web. 26 Dec. 2009.<http://scienceray.com/technology/transport/the-motion-of-vehicles-in-water/>.

y Sailingahead.com - History of Sailing." Sailingahead.com - Welcome to your sailing adventure!.N.p., n.d. Web. 26 Dec. 2009.<http://www.sailingahead.com/information/history_sailing_I.htm>.



y Sailingahead.com - History of Sailing II." Sailingahead.com - Welcome to your sailingadventure!. N.p., n.d. Web. 26 Dec. 2009.<http://www.sailingahead.com/information/history_sailing_II.htm>.

y The physics of sailing." Physics animations and film clips: Physclips. Web. 26 Dec. 2009.<http://www.animations.physics.unsw.edu.au/jw/sailing.html>.

y Wing / International Marine/Ragged Mountain Press; 4 edition (July 30, 2008), Charlie, and Dr.

Jim Austin.G

et Your Captain's License. 2008. Print Edition.

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Physics in Sailing and Modern Boating (High School)