Navigation

Introduction

Navigation is most of the time the biggest issue that is causing problems for alot of people on the water. There are so many things to consider: Compass, Charts & Maps, Tidal Tables, GPS, AIS, and many, many more things.

Caution! Only use this information to educate yourself. The information on this page about navigation without equipment is purely informational! We are not responsible for any damages when you use the mentioned info as your main and only means of navigation!

Estimating angles and distances on open water

(only when precise position fixing is not required)

Hold your arm straight out and “measure” with your hand. You can estimate roughly these angles:

Hold your hand like	Angle
Fully spread hand, thumb tip to little-finger tip	20°
Width of a fist with the thumb extended	15°
Width of a closed fist	10°
Width of a thumb	3°
Width of a little finger	2°

Estimating distances

In good visibility:

• Lateral and cardinal buoys can be seen at approx. 3 km.
• The shape can be distinguished at approx. 2 km
• The colour and topmark at approx. 1.5 km.
• The distance to the horizon at standing eye height above the water is approx. 4.7 km
• At an eye height of 3 metres above the water this is approx. 6.2 km.

Introduction

Buoys are most of the time a confusing issue for alot of people. They also use different systems around the world! We try to make things a bit easier for you here. And there are some old European sayings that might help you!

Systems used

• SIGNI: Europe Inland Waterways
• IALA Zone A: for Europe, Africa, Asia, Australia
• IALA Zone B: for North & South America, Japan, Korea

The systems are different for inland waters and for open water. Within European inland waters, the SIGNI system is used. At sea, the IALA system is used. For Europe, Africa, Asia and Australia (Zone A) the IALA and SIGNI system use the same rule as the SIGNI system: Looking down stream (towards sea), than:

• Green is LEFT when sailing out to sea
• Red is RIGHT when sailing out to sea

And that is the opposite when coming from sea. Therefore the following sayings are "true":

When Fishermen had their Green light on the side of the Red buoys, that meant they are heading towards sea. (Red as the color of the blood that flows out of a broken heart.) But when they come home and have "Green on Green" this implies that they come home. You actually are going Upstream. (You can see here how that looks like on your boat).

What is the "left", or "right" bank?

The most confusing part is, what is the left side bank, and what is the right side bank of a waterway. Lets start with explaining it with a river: (Fig.1 Signi Left/Right)

You always look "towards sea" or "downstream" and then the buoys are:

• Left bank = Green = Uneven numbers (1,3,5,7)
• Right bank = Red = Even numbers (2,4,6,8)

And now I will explain where most people go "wrong" in their head. People are told from being a child, that anything on your left hand side, is "left" and anything on your right hand side is "right". This is pretty normal when you are driving. But with boating it is a bit different. But I guess I can make it more clear to Europeans:

Consider yourself in a regular street in a city or town. Both sides of the street have houses. And all houses are numbered and you have two sides to this street:

• The side of the street with the EVEN numbers
• The side of the street with the UNEVEN numbers

It truly does not matter from which side you enter this street, because the houses with the even numbers will always on the same side of the street, just like the uneven numbers will always be on the same side of the street.

So lets assume you are driving into the street and the numbering starts at #1 at YOUR right hand side. (Green Buoy #1). And automatically you know that #2 will be on YOUR left hand side. (Red Buoy #2). You are now actually coming from sea, and going up the river, heading home.

Now, you turn into the street from the "high" numbers. Now you see that the even numbers are now on YOUR right hand side (Red Buoy #66), and the uneven numbers are now on YOUR left hand side. (Green Buoy #67)

In both cases, nothing changed to the houses or the numbering. You still have the EVEN (RED) and UNEVEN(GREEN) numbering on their designated side of the street. That did not change at all. Only you changed direction!

Another help might be: Right uses the same letter to start as Red. Caution! this is only for buoys, NOT for your navigation lights!!!!!!!!

The moment that you enter zone B (North & South America, Japan, Korea) it is exactly the opposite. And they use the system also for INLAND waterways in North-America!

We can also state that the European SIGNI system is flawlessly migrating into our Zone A IALA system. We do hope that this takes away a bit of the confusion! More information below the table with buoys.

SIGNI System

Left side (CONICAL)	Right side (CAN)	Description
		Fairway marking (main buoyage line).
		Recreational buoyage: usable water outside the main buoyage.
		Boundary of a special area; marking for through traffic.
		Stake marks; also called posts/stakes/brush marks. Tied together: same meaning as a green buoy (LEFT SIDE). Branches sticking out: same meaning as a red buoy (RIGHT SIDE).
		Perch mark: dangerous point or obstacle, groyne, object in the water, etc.
		Separation buoy: main channel on the left. This buoy lies in the red (CAN) buoy line and, when going downstream (towards sea), should be kept to starboard (right) of the vessel.
		Separation buoy: main channel on the right. This buoy lies in the green (CONICAL) buoy line and, when going downstream (towards sea), should be kept to port (left) of the vessel.
		Separation buoy: channels of equal importance. (Spherical topmark. Also called a “mid‑channel buoy”.)

Navigation on inland waters

To navigate rivers, canals and lakes safely, signalling is used according to the SIGNI system (Signalisation des voies de Navigation Intérieure). This applies to European inland waters. Due to the fact that the SIGNI and IALA Zone A follow the same rules, the Scheldt, Waddensea, and Ems-Dollard will have the same structures. The buoyage/signage is divided into lateral marks and cardinal marks.

• Lateral marks indicate the sideways limits of a fairway.
• Cardinal marks are used on larger waters to indicate dangerous points.

Lateral marks

To make the course of a fairway visible, marks are placed along its edge at regular intervals. When marking the navigable part, the terms left bank and right bank are used. Determine them with your back to the higher side (where the water comes from) looking toward the lower side (downstream, where the water goes). For canals this is also from high to low, i.e., towards the lower level. For other waters, the following rules are agreed:

• Tidal area: looking in the direction of the ebb stream (i.e., “towards” the sea).
• Side channels and gullies: looking in the direction of where the main fairway is.
• Lakes: in the direction of the outlet to open water.
• Randmeren (border lakes): looking from Amsterdam.
• Rivers: looking down stream/down hill, e.g towards the sea (Fig.1).

The buoyage used can be recognised by shape and colour. See the table earlier on this page. To be clear, when you are going downstream, that is how you determine the left and right bank of the river (or canal). So, you stand on top of the mountain, looking down towards how the water flows (Fig.1), the left hand side is the left bank. The right hand side is the right bank. And this does not change when you go upstream.

• The left side is conical or has a conical topmark and is primarily green.
• The right side is can‑shaped (cylindrical) or has a can topmark and is primarily red.
• Junctions are indicated by spherical buoys with a combination of both colours.

Holding a course without compass or GPS

If the sun is visible, you can find north by pointing the hour hand of an analogue watch at the sun. The imaginary line that bisects the angle between the hour hand and the 12 o’clock position indicates the north–south line within a few degrees. In the northern hemisphere, the extension of this bisector points south; north is 180 degrees the other way, behind the observer. Do not forget to account for daylight saving time (subtract that extra hour first).

When it is overcast, you can sometimes still apply the same idea by placing a knife with the tip of the blade on your thumbnail. The blade casts a faint shadow that changes width as you rotate the knife. When the shadow is thinnest (or disappears), the flat of the blade is aligned with the sun. Keep the watch’s hour hand parallel to the blade and determine the north–south line as described above. Use this method with care: if the sun is blocked by a thick cloud but the sky to the east or west is bright, it can mislead you.

None of these methods works in dense fog. However, it is still possible to steer a reasonably straight course without a compass; lead a fishing line from the tip of a rod out over the stern. The line will point straight aft while you keep course; if you deviate, the line will swing to one side or the other.

DISCLAIMER: Do NOT use this for REGULAR navigation! This is only to be used in extreme emergencies, where you do not have any other means of navigation! You cannot hold us responsible for any damages in whatever form, when you use this as your main type of navigation and get in trouble.

Fishing poles on the IJsselmeer

Fishing grounds along the IJsselmeer shore are marked with fishing poles—simple stakes or branches in what looks like a random pattern. It is best to avoid these areas by staying about 1 to 1.5 km off the shore. In the middle of the IJsselmeer, nets are also used and are more clearly marked. These are set nets (“war nets”), about 1 to 1.5 metres high, with floats and a weighted bottom line. For most “normal” pleasure craft, passing over them is usually not a problem, but deep‑keel sailing boats should detour. A row can be up to 500 m long with a float and flag between each net; the ends are marked by floats with two flags one above the other (often black).

Looking at tide information

Tidal Water levels – High water and low water

The Netherlands, Germany, Denmark and Belgium have several tidal waters:

• Western Scheldt
• Eastern Scheldt
• Waddensea
• Ems & Dollard
• Jade bosom
• Weser Mouth
• Elbe Mouth
• North Sea

Current – the horizontal tide

Tidal movement creates an ebb current and a flood current. On most hydrographic charts you can use the tidal stream tables. HP 33 now contains the current atlases. You can also use current slide charts. These provide a general impression of current direction and strength and are a handy aid to see when you can depart or arrive. They are not very precise, but they are practical.

Tides involve not only rising and falling water levels, but, also horizontal current in the water. In Fig.7 you actually see outgoing tide from the Waddensea in between Den Helder and Texel.

• With upcoming tide (from low water to high water), water "pushes" you towards land.
• With offgoing tide (from high water to low water), water "pulls" you towards sea.

Tidal water levels determine whether you can continue, or get stuck, based upon your draft. Therefore tides and their currents determine the most favourable times to depart/arrive.

• Going to sea: From just before high tide, using the outgoing tide to pull you.
• Coming from sea: Try to come into the mouth of a river at low tide, so the tide will push you in.

Water level height – the rule of twelfths

Using the rule of twelfths you can estimate water depth. We assume there are on average 6 hours between HW and LW.

• In the first hour, the change is 1/12 (add or subtract 1/12)
• In the second hour, the change is 2/12 (so 3/12 total)
• In the third hour, the change is 3/12 (so 6/12 total)
• In the fourth hour, the change is 3/12 (so 9/12 total)
• In the fifth hour, the change is 2/12 (so 11/12 total)
• In the sixth hour, the change is 1/12 (so 12/12 total)

So the total range is divided into 12 parts. This is a rough estimate, but it works well enough.

Spring tides and neap tides

There are also spring tides and neap tides. In the first case the water reaches its highest highs and lowest lows; in the second case it does not rise or fall as much. The tidal range is then smaller. You can estimate the difference between HWS (spring) and HWD (neap) with the one‑seventh rule, because there are 7 days between HWS and HWD.

On this site, you've seen already a couple of times "Opvaart" or "Afvaart". That are the dutch "slang words" for going Upstream or Downstream. As you can imagine, going upstream, is way less fuel efficient than going downstream. For example the river IJssel, that is fast-flowing, going Upstream, will take serious time and therefore also serious amounts of fuel. Therefore, going in the "Afvaart" is economically way better.

The image here, will clarify what Opvaart and Afvaart mean and look like. In the image the river flows from left to right. So, going from Right to Left, you are going against the current. And going from Left to right, you are going with the current.

Here some of the definitions that must be clarified which are in place here:

STW

Speed trough Water. AKA Hull Speed
The speed of your vessel trough the water.
You can calculate your hull speed here.

SOG

Speed over Ground.
The real speed you will see on your GPS.

River Current

How fast the water flows trough the river.
Going with the flow: Add it to your STW (+)
Going against the flow: Substract it from your STW (-)

Why prefer downstream (Afvaart)?

Afvaart

10 km/h speed trough water + 4 km speed of the current = 14 km/h speed over ground.

Opvaart

10 km/h speed trough water - 4 km speed of the current = 6 km/h speed over ground.

Note

Actually that is pretty simple to answer: Fighting yourself against the current gives you a nice speed trought the water (STW), but a slow speed over ground (SOG). When you are going downstream, you go with the flow, and your speed trought the water will remain the same, but the speed over ground will be:

(speed trough the water + water flow speed) = Faster Speed over ground.
(speed trough the water - water flow speed) = Slower Speed over ground.

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