Experience on a sailing trip

Navigation and speed diagram

of a sailing yacht

Marco Brigadoi 5A

Gymnasium Kirschgarten

Basel 12/2009

Index page

Index 2

List of figures 3

List of tables 4

Preface 5

1. Introduction 6

2. Physics of sailing 7

3. Results 9

3.1 Routing 9

3.2 Tasks on the boat / Documentation 11

3.3 Navigation: once – today 16

3.4 Speed diagram 20

4. Conclusion 22

5. List of literature 23

List of figures

Picture 1:

http://ffden-2.phys.uaf.edu/211_fall2002.web.dir/josh_palmer/041100sc_figure6.gif¨

Picture 2:

http://de.wikipedia.org/w/index.php?title=Datei:MariahQuarterView.jpg&filetimestamp

=20050929211204$

Picture 3:

http://www.yachtbooker.com/media/images/medium/sun_odyssey36i_pic2.jpg

Picture 4:

http://cachecounter.files.wordpress.com/2009/06/anniversary-cr.jpg

Picture 5:

http://images.google.ch/imgres?imgurl=http://www.vos.noaa.gov/MWL/aug_08/Image

s/lead_line2.jpg&imgrefurl=http://www.vos.noaa.gov/MWL/aug_08/navigation_tools.s

html&usg=__ZQhUmVZRPadscgucvH8LyyQ5oOA=&h=832&w=1174&sz=523&hl=de

&start=1&sig2=FMfzRX3sPAvbPixrKGgaXA&um=1&tbnid=dBo2M5-

FEG_MwM:&tbnh=106&tbnw=150&prev=/images%3Fq%3Dlead%2Bline%26hl%3Dd

e%26sa%3DN%26um%3D1&ei=6wswS_mqDITGsgaOmfDBBw

Picture 6:

http://www.ssplplrints.com/lowres/43/main/15/93845.jpg

Picture 7:

http://en.wikipedia.org/wiki/File:Sextant.jpg

Picture 8:

http://www.bayercropscience.com/bayer/cropscience/cscms.nsf/id/GPSinderLandwirt

schaft_Agro/$file/gps_507.jpg

Note:

Unfortunately I lost my camera with all my pictures of the sailing trip! That’s why I can

not show any impressions. I am sorry for that!

List of tables

Table 1:

Sea map with the drawing of our routing. This way were sailing in five days.

Table 2:

Made on my own measurements while the experiment

Preface

I’ve chosen the topic ‘sailing’, because I am confronted with it since my childhood. So

my grandfather is skipper for more than 20 years. He is sailing at least twice a year,

that’s why I got to know so much about it. I was never before with him and his crew

on a sailing boat, but it always interested me. So I just thought about doing a sailing

trip with him as my skipper and teacher. Of course I knew that this topic is too much

for such a work, so I’ve decided to take some special things out of it, which I am

going to explain later. It is obviously the theoretical part of physics of sailing being

very short in contrast to my experience report and experiments with the boat.

But it was so fascinating for me that people are sailing for over 1000 years ago. That

was the main point leading me to my topic.

1. Introduction

One thing that I am going to deal with is a sailing trip. The sense of it is to document

and plan such a trip. So I have to answer the following questions: What are my

tasks? What do I have to do in these tasks? How such a trip should being planed?

Navigation will be the main part of the tasks I have to do on my experience report. I

am going to compare how the navigation once was and how it is today. What

instruments did people used to have? Which ones are needed today? What is more

exactly?

I will also have to plan a route without any help of digital machines, so like people did

in ancient years.

The deviations are an important fact, which have to be concerned, too. There is for

example current, wind leeway, variation.

That’s more or less, what the first part of my maturity work handles with. The other

part will be a speed diagram of a specific boat. This experiment takes place on a

Swiss lake. The task here is to find out the speeds of a yacht at several wind speed.

Also here multiple facts have to be considered, like the angle of the boat to the wind

and the speed of the yacht. What influences have to be dealt with? For example the

trimming of the sails or heeling.

So at the end I have to sail twice with my grandfather, once for the experience report,

with the several tasks (navigation,…) and once for the speed diagram with all its

influences. These are the main topics of my maturity work, of which I am going to

have a deeper look at. But I also do explain in short and as easy as possible terms

the physics of sailing. For big and small boats as well for boats with one or more

masts. I think it is very strange that only the wind is able to speed up a heavy boat of

a speed of sometimes more than 12 knots per hour. Why someone had such an

idea? Does it depend on the weight of the boat? What physical forces are involved,

so that it is possible for a ship to move?

For finishing my work, I’ll make a summary of the three parts together. So it is going

to be obvious at the end, what I’ve learned on the sailing trip and how sailing actually

works.

2. Physics of sailing

There are four important sections of the basics of the physic.

Actuation:

Two effects are responsible for a ship being able to move: the wind pressure on the

sail and the airflow around the ship. It depends on the angle to the wind, which

effects overbalances. But most of the time the both are overlying themselves.

The main reason why driving exists is that the force of the wind pressure is

transferred into the mast and then this force passes into the hull.

Wind pressure on the sail:

If the wind lies abaft to the boat, the driving is raised by the resistance that occurs,

when the wind hits the sail. There is no air flow at the moment and the wind tries to

put away the resistance.

In earlier times, this technique was much more common, because the sails were

bigger and so there was more area for the wind.

Parts of a Bermuda sail, often used today

(Picture 1)

Air flowing around the sail:

This is the same effect that occurs on wings of plane. The bow of the sail is

responsible for complex, aerodynamic streaming around the sail. The main point is

that the air gets distracted from its original direction. The force is needed for that, is

converted into the driving of the boat.

The angle between the sail and the wind is the most important influence of the

driving. If it is too small the sail flatters but if it is too huge the driving collapses,

because there is no air stream anymore.

Stability:

The keel has to contrast against the wind pressure coming from the side, so that the

boat doesn’t overturn. But the will be bunked, this is called heeling. The effect to

compensate this heeling and get the boat in a normal position again, is called

stability. There are two types of stability:

Formal stability: the form of the hull is responsible for the stability (less stability at the

beginning, but therefore a high one at the end)

Weight stability: a deep fixed keel is responsible for the stability (high stability at the

beginning, but therefore a less one at the end)

Ship with a keel on the bottom

(picture 2)

3. Results

3.1 Routing

Education trip Swiss Sailors Club in the Balearic sea area

In this chapter, I briefly show our routing. I just write where we were when at the end

of the day. The detail information about the several days will follows in chapter 3.2.

(Information according to log book)

Day 0 : 11:00 departure from Real Club Nautico (Palma)

Day 1 : 24:00 sailing in open sea right next to Porto Colom. A night trip follows.

Day 2 : 15:00 sleeping in open sea in the bay of Cala Grao with bower anchor.

Day 3 : 24:00 sailing in open sea. Again a night trip follows. In the Canal de Mallorca

strong NW-wind (5-7 Beaufort*).

Day 4*: 12:00 strong storm with organic gusts from NW with the maximum speed of

50 knots (7-9 Beaufort).

Day 4 : 19:00 sleeping in Porto Ibiza.

Day 5 : 24:00 arriving port of registry in Real Club Nautico.

Boat information:

Yacht: Serxa

Type: Sun Odyssey 36i

Year: 2007

Length: 10.69 m

Broadness: 3.59 m

Draft: 1.94 m

Motor: 130 l

Water tank: 355 l

People: 4 + 2

Bathroom: 1

Table 1

3.2 Tasks on the boat / Documentation

We were sailing in open sea from the 5. until the 9 April. In these 5 days we’re driven

a new SSC (Swiss Sailors Club) course record. In the list below you can see what my

tasks were and how the day elapsed on every single day.

But first I am going to show in general, who the tasks has to do and what is to do in

each one.

Buying is raised by the whole crew

Rudder arrangement is raised by the skipper according to the rotation system

(means everyday another person has to do the task)

Navigation arrangement is raised by the skipper according to the rotation

Kitchen duty arrangement is raised by the skipper according to the rotation

Night trip arrangement is raised by the skipper

Overview of tasks

Skipper controls and checks the crew, rules the course and the sailing guide,

he is responsible for safety, order, papers, clearing inwards, etc.

Co-Skipper he is the replacement for the skipper.

Bord cash is carrying the cash book about the deposits, investments and dues.

Clear to run the whole crew has to make sure that all hatches, sea cocks and gas

valves are closed. There mustn’t be any clothes on the rail and the

salon and the berths have to be seaworthy cleared.

Rudder guides the rudder, holds the course according to navigation and trims

a sail in an optimal way.

Navigation this is the task, in which you have the most to do. You have to take

care about: calculate the course according to the skipper, routing,

bearing, machine service, instruments, lightening etc.

Meteo is looking at wind, weather, air pressure and the sea.

Kitchen duty is responsible for the catering on board, is doing the shopping of food,

drinks, ice etc. He is controlling the water asset and he cleans the

salon.

Elapsing sailing trip

Saturday, April 4, 2009:

As we arrived in the port, a man working there was receiving us. He showed us

where our boat is standing and then he gave us a list with things should be on board.

That was the first thing we had to do, to control the assets on board. Afterwards we

had to tell him what was missing and then he brought it to us.

At 06:00h we were finished with the entire bureaucratic thing and so we had time to

prepare the buying. Water is the most important tool, because you need it for

cocking, for washing and for drinking. We also bought food for diner and for the

breakfast next morning. At 23:30h we went sleeping.

Sunday, April 5, 2009:

At 09:00h all of us had to stand up. We were having breakfast. My task was to wash

and dry the dishes. Then the trip for this day had to be discussed. The skipper

decided to drive out after sight, so without any exact navigation. At 10:30h the boat

had to be clear to run, which means to make sure that all hatches are closed and that

nothing can fall down while sailing. The ideal condition for driving out the box (that is

where the ship is standing in) is, if the wind lies abaft. Now the leaving maneuver

follows. Me and the skipper had to take away the mooring while the other crew

member is navigating the boat. The mooring has to be deep down in the water, so

that it doesn’t touch the rotors. Then I had pick up the docking line and the fender

(fender are plastic pillows filled with air to protect the boat of marks).

Afterwards the mainsail has to be fixed. Release the main sheet. Fix the main halyard

(line to take up the mainsail), until the sail is at the top. The last thing to do, is to fix

the Genoa (additionally sail to the mainsail), until it is rolled out.

We could put off the motor, because we are only sailing now. This was the whole

leaving maneuver, which needed totally ten minutes.

At the beginning it has to be considered to take off the Dirk, because it was only used

for the security of the boom (the boom is used to trim the sails fixed on it). While

sailing, this security isn’t needed anymore, because you have to trim the sail (lay the

sail in an optimal way to the wind).

At half past three, there was no wind anymore, so we had to put on the motor again

and take down the Genoa. Two hours later the wind flew again and so we could sail

like before. That was the point, when I had to navigate the ship. This is very difficult

and it’s absolutely not moving like a car. The ruder is huge which means that the boat

is exactly to control. But the difficulty is that it reacts some time later. First I thought

the ship doesn’t react at all, so I navigated it more and more left. That was a big

mistake, because after some time the boat drove a sharp curve to the left. Since then

I treated the ruder very carefully.

At 18:00h the skipper took over the ruder, so that he could dive into a bay, where we

made a break. There we took down the sails and placed the anchor. Again my task

was to wash the dishes after dinner.

At nine o’clock we decided to make a night trip. So the anchor has to be picked up

and then the leaving maneuver followed like before.

This was the arrangement for the night trip:

21:00 till 23:00 Oskar (skipper)

23:00 till 01:00 Marco (me)

01:00 till 03:00 Robert (crew member)

03:00 till 05:00 Oskar

05:00 till 07:00 Marco

07:00 till 09:00 Robert

So I had to stay awake till 01:00h. I was very tired, because it was so boring to watch

out in the darkness. That’s the main task in the night trip, to watch out if there are any

other ships or any dangerous objects in the water.

Monday, April 6, 2009:

We were in the middle of the night trip. I just could sleep until 05:00h, and then I had

to stand up for my next shift.

At 09:30h we arrived at the port Colom. We stayed there for three hours and then we

left the port. Again the leaving maneuver follows. But there was one problem; the

wind flew directly from the front. So that we could sail out of the bay, we had to drive

a zigzag way. There is only used a change of the Genoa when you tack. On one side

fix the line on the winch easily and the other side, fix it tight. That’s how to perform a

turning. We were sailing until in the evening and then we made again a break at

19:00h. The skipper drove into a very small bay. There the anchor has to be placed

and so the boat was fixed. With the Dinghy (a small type of boat, often carried by a

larger vessel) it was easy to come to the land. On land we made our buying for the

next day and after that we had a diner. After that we drove back to boat and went

sleeping.

Tuesday, April 7, 2009:

At 09:00h standing up for all. Right after there was a discussion about sailing from

Menorca to Ibiza in one trip. There had to be ideal wind conditions and this was the

case. So we decided to put it into action. Anchor aweigh! Here it is to consider only

taking up the anchor, when there is no pressure on the chain.

Again both sails are going to be fixed. We could sail to the wind.

At 03:00h a very small storm came up. The strength of the gust was something about

25 km/h (this is 4 Beaufort: moderate breeze).

At 04:00h Menorca was gone. On the way to Mallorca (in open sea), the wind

increased a lot. The boat was waggling a lot and that was the point, when I became

bad. It was horrible, but fortunately the wind calmed down a bit later.

So that we could sail from Menorca to Ibiza in one trip, we again had to make a night

trip. This time it looked like that:

20:00 till 22:00 Robert

22:00 till 24:00 Oskar

24:00 till 02:00 Marco

02:00 till 04:00 Robert

04:00 till 06:00 Oskar

06:00 till 08:00 Marco

Wednesday, April 8, 2009

The first shift wasn’t very interesting. It was all calm and just normal. So I could sleep

well at 02:00h. Unfortunately I had to stand up at 06:00h again for my shift.

And now it happened all at once. Of course I couldn’t stand that situation on my own,

so had get help from the skipper. He was surprised what was going to happen,

because the weather forecast didn’t say so. Suddenly a big storm came up. First

there was wind strength until 50 km/h (this is 7 Beaufort: high wind, near gale).

But then, one hour later, it was horrible. The storm wasn’t to stop anymore. The wind

strength was until to 100 km/h (this is 10 Beaufort: storm, gale).

The skipper had a lot to do: the mainsail must have been taken in wholly. And the

Genoa he had to reef to a storm jib. Now its amplitude was only 5 square maters.

Like that we sailed until we arrived in Ibiza. There the storm calmed down and we

rolled the Genoa in. So I navigated the boat with motor on into the box in the port

Ibiza. We were all very happy that the storm was over and we could relax. We were

so tired that we made a break the whole day. We only had to buy food, and that was

it for Wednesday.

Thursday, April 9, 2009

We all had to stand up at 09:00h, like always. At 10:30h all clear to run!

So that’s the point, when we left Ibiza again. This time, the wind was very calm,

something about 3-4 Beaufort (20 km/h). We ate lunch on the boat. I made a

sandwich for all. We could sail to the wind until we arrived at Mallorca. 20 SM (sea

miles) ere Mallorca, there was no wind anymore. So we put on the motor and drove

into the port of Palma.

At 00:00h we went sleeping in our last station.

That was more or less all about my experience documentation. In the remaining two

days, we only gave back the boat and flied back home at Saturday, April 11, 2009.

Our sailing yacht: Sun Odyssey 36i

(picture 3)

3.3 Navigation: once – today

On task on the boat, navigation, is such an important part that I have to write an own

topic about it. I am going to how people used to navigate and what instruments are

used today.

Once:

I’m not going to tell you all the historical details about sailing. Only how the people

navigated in earlier times, which is very interesting. How could sailors 2000 years

ago know, if they drive the correct route? Let’s have a look.

The very basics of navigation are to look how the orbs are moving and the knowledge

about the calculation of distance. The sailors at that time were aware of this basics,

otherwise they wouldn’t have been able to navigate the ship from one place to

another. Circulation of information and making of drawings was very important, so

that the knowledge could have been distributed. Bu there was one problem, namely

the secrecy of those information. That’s why we don’t know a lot today how people

could drive a ship that exactly. Sometimes the route was very long and so there also

had to be a night trip. For this night trip you need to be well aware of navigation,

especially about astronomy. This forced people to create instrument to measure the

angle of the orbs to earth.

For having a good knowledge about navigation in ancient times, four main points

were important:

- People had to make drawings, which primitive maps resulted from.

- There had to be instruments to assign the direction, where you drive to. For

this the sun could have been a help and at night the stars or the moon.

- An instrument for measuring the time was need to, so that people knew what

time it is.

- Don’t sail along the coast all the time, because in the open sea it’s much more

save. There are less wind changes or not that big waves.

Here is a list of instruments, people used to have for navigating.

Compass Rose: was used to be able to know which direction you drive to.

Four compass Roses that were used in ancient times

(picture 4)

Lead line: A weighted line, lowered from the deck of a ship to determine water depth

A new lead line to measure the water depth

(picture 5)

Sand glass: for being able to know how much time runes over.

Four sand glasses in one machine

(picture 6)

Sextant: used to measure the angle between an orb and the horizon.

A very old sextant, used to measure angles

(picture 7)

Today:

Of course the elderly methods of navigation are still used today. Like if you plan the

route on a sea map with circle and Set Square, this is an old way to navigate. The

most important point, why we still use these techniques is, if once a new technical

machine would fail, you would be lost. But the old techniques you just have to learn

and then you are never lost.

Anyways one of the latest machines is GPS. It’s very exactly, of course more exactly

than calculated by ones own.

GPS (Global Positioning System) is based on satellites, which send out constantly

radio signals to determine the momentary position and time. Normally there are only

three satellites needed to identify the exact position and altitude. But three are not

enough, if you want to know the exact time, for that a further one is needed.

GPS system shown with three satellites (picture 8)

Another example is the autopilot. It’s like if the boat is controlled by its own. You can feed in a computer the coordinates, where you want to go to. With an accuracy of 10 to 50 meters, you arrive at the desired place.

3.4 Speed diagram

speed diagram (16 knotes)

5

6

78

9

10

1112

30 50 70 90 110 130 150 170

yaw angle relative to the boat (degrees)

sp

ee

d o

f b

oat

(kn

ote

s)

table 1

Boat information:

Type: Salina 48

Year: 2008

Length: 14.3 m

Broadness: 7.51m

Draft: 1.07 m

Motor: 2 * 40 CV

Water tank: 479 l

People: 12

We made the experiment with a catamaran, which means a boat having two hulls.

Such a catamaran doesn’t sail very well close to the wind. This means the yaw angle

to the boat is something about 40 degrees. And at that point, the boat has the least

speed of 5.5 knots. The highest speed you can reach, when you are sailing wind

abeam. So the wind stream hits the boat exactly in a 90 degrees angle. This is also

called the “driving effect” (Bernoulli’s law). And now the speed almost decreases in

the same way, as it increased.

The results do not depend on which side of the boat you are doing the experiment.

There are several influences creating the sailing speed, like the motion of the sea.

The important facts here are the altitude of the waves and the flow of the water.

4. Conclusion

The experience trip was a big success. I had a clear and deep look into all the tasks

on the boat, so I could also achieve them in practice. Some of them were really

difficult, like the navigation of a rout or to control the ship. This was a big experience

for me and a help for a better dealing with a sailing boat. Additionally we had very

luck with the weather, because almost all weather conditions were available. So I

could also learn what is to do when there is a huge storm or when there is absolutely

now wind.

The comparing of the navigation in ancient times and today, didn’t really work like I

wanted to. All the information about the early times are very saved, because they are

important documents. But of course the instruments people used to have are well

known. So at least I could list them and show some pictures.

Today’s navigation wouldn’t get along with the help of the old techniques, because if

one of those latest machines would fall out, you would be lost anywhere in the open

sea without knowing where you are.

The speed diagram experiment found place on the Constance. Fortunately we had

good weather conditions, what made it easy for me to do the experiment. We had to

it with a catamaran, because no other ship was available. But it worked with that boat

as well, better than I thought. So the speed diagram succeeded as well. I could find

out some influences that are involved in the speed of a boat, so that it gets clearer

why the ship has exactly that speed. So this part of my work processed well, too.

I had to find out that the physics of sailing is much more complicated than I thought.

This was a big problem, because I wanted to hold this topic as short as possible. So I

had to shorten some physical forces and effects and explain it just in an easy way.

Maybe this didn’t worked really good, but I hope its help to understand it better, why a

boat doesn’t overbalance or why it is able to move with its weight.

At the end it is to say, that almost all of my questions could be answered and that it

often was according to my expectations.

However this work also should be a help, for someone who wants to start sailing. So

he is already known what on a sailing trip is to do, and how the physics of sailing

does work.

5. List of literature

Books:

Schult, Joachim: Segler-Wörterbuch

Internet:

http://en.wikipedia.org/wiki/Beaufort_scale

http://de.wikipedia.org/wiki/Segeln#Altertum

http://www.360derece.info/deutsch/antik_navigasyon.htm

http://www.luftrettung-

hamburg.de/html/navigation_grundlagen.html#Rechtweisender%20Kurs%20rwK%20

(TC)

http://de.wikipedia.org/wiki/Kompassrose#Die_Windrose

http://woerterbuch.reverso.net/englisch-definitionen/lead%20line

http://de.wikipedia.org/wiki/Sextant

http://de.wikipedia.org/wiki/Global_Positioning_System

http://www.fountainepajot.com.au/salina-48-catamaran.htm

http://www.leo.org/