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Zeus - Sailing Navigation - ProNav


Zeus - Sailing Navigation

Essential Guide



Passionate about sailing

B&G have been world leaders in sailing instrumentation since 1956,

when the company was founded by Major R.N. Gatehouse and Ronald

Brookes who had formed a partnership the previous year to develop

and manufacture navigation electronics for sailing yachts. Gatehouse

had a keen interest in both cruising and racing.

Since this time B&G navigation systems have been

relied upon by generations of sailors for their

performance and reliability. They continue to provide

the best equipment available for cruising or racing and

focus on products designed for specifically for sailors.

The B&G range includes instruments, sailing autopilots,

chart plotters and radar.



The new Zeus range

B&G’s new Zeus range is a

multi-function navigation system

designed specifically for sailing.

Zeus provides sailors with easy

access to features for sailing

navigation and allows total

control of navigation on-board.

At the core of the B&G Zeus system is a high

specification multi-function display, combining

powerful processing along with a very high-quality,

sunlight viewable, screen.

The Zeus display – available in 8” or 12” variants -

allows rapid access to a wide range of features. A

combination of a great user interface with direct

access keys, alphanumeric keypad and rotary dial

ensures features can be controlled in a quick and

straight-forward fashion.


The power of Zeus is available to all - Zeus is

compatible with most instrument systems via the

industry standard NMEA 0183 and/or NMEA 2000

protocols. See the B&G website for connection


B&G H3000 systems may connect via the H-Link

USB connection which gives additional functionality

including accessing calibration data on H3000

and displaying more advanced functions. Hercules

Performance and Hercules Motion users can also view,

edit and save their Polar Tables.


B&G Zeus receives

Sail Magazine's 2011

Freeman K. Pittman

Innovation Award.

Broadband 3G awarded

“Best on Test”

from Practical Boat

Owner Magazine.

B&G Zeus wins NMMA

Innovation Award at the

Miami Boat Show 2011.



Key features:

Chart plotting

• Clear presentation of integrated regional premium cartography

• Sail navigation overlay

• Supports additional cartography from Navionics

• 2D/3D, terrain shading and photo overlay options.


• GRIB weather forecast display

• Sirius Weather (US only).


• Exceptionally clear radar PPI display

• Chart overlay mode

• Broadband Radar compatible. Providing low power

use and InstantOn TM


• Instrument data displays, user configurable

• TimePlot and WindPlot trending charts

• H3000 instrument integration via H-Link

• Compatible with most NMEA 0183 and NMEA 2000 systems.

System Intergration

• CZone distributed power system compatible

• SonicHub multimedia system compatible

• AIS display

• StructureScan – see what’s below

• Autopilot control.*

* Selected autopilots only




What does the weather overlay do?

The unique weather functionality of the B&G Zeus allows the

user to view forecast data overlaid on to the chart to gain a clear

understanding of the conditions that they are likely to face.


• Display of Wind Speed and Direction

• Display of Barometric Pressure with isobars and

pressure centre indicators (High or Low)

• Manual time step control – select any available

forecast time

• Animation option shows how weather systems

are likely to develop and allows the sailor to take

appropriate steps to prepare, or route around

• Cursor Info feature allows quick assessment of the

forecast at a particular location and time.

B&G Zeus supports two forms of weather data; GRIB

files, which can be downloaded for any location in the

world, and the SIRIUS Marine Weather Service, which is

available only in North America.



What are GRIB files?

GRIB files are the format used by the world’s

meteorological organisations to store and exchange

forecast data. Some organisations (such as the US

National Weather Service) make their data available for

general use.

Most free sources of GRIB data use the US General

Forecast System (GFS) to provide the end user with a

regional subset of the global forecast. The standard

resolution of GFS data is 0.5° with forecast time

intervals of 3 hours. The duration of the forecast

depends on the source of your GRIB files, but tends to

range from 3 to 7 days.

It is important to note that most free GRIB files are

raw outputs from numeric computer models, if very

high quality data is required then subscription services

that either run higher resolution local models, or have

additional processing by meteorologists are available.

What is Sirius weather

When connected to a Navico Weather Module (WM2),

you can subscribe to and include the Sirius Marine

Weather Service on your Zeus system.

The Sirius weather service covers inland US waters and

coastal areas into the Atlantic and Pacific Oceans, Gulf

of Mexico and Caribbean Sea.

The weather products received vary depending

on your selected subscription package. Sirius also

provides satellite radio services that integrate with the

SonicHub audio server.

Further information:



Viewing Forecasts

What can I see?

Information at cursor

• Position

• Range & Bearing to Cursor

• Wind Speed (Kn)

• Wind Direction (ºM)

• Barometric Pressure (mb)

• Time of displayed forecast

• Time from start of forecast file (+39 hours).

Weather overlay

• Wind barbs show the direction and speed

of the wind forecasted

• Isobars indicate barometric pressure. High

and Low pressure centres are identified.

Animation controls

• Time control for manual stepping

through GRIB data

• Speed control for animation of GRIB file

at low, medium and high speed.

A GRIB file contains forecast information for a set number of days.

It is possible to animate the weather data which shows how weather

systems are developing.

The speed dial allows the user to set the speed at

which the Zeus unit will animate the GRIB file, time

steps and duration vary depending on the source of

your GRIB file.

Along with the automated animation it is also possible

to use the time dial to step through the file manually,

viewing the forecast for a specific date and time.

As you move the cursor around the chart you will

see the wind speed, wind direction and barometric

pressure values at the cursor point for the current

forecast time selected.

The angle of the wind barb indicates the geographical

wind direction from 0 to 359 degrees. Wind speed is

indicated by a combination of short barbs, long barbs

and pennants at the end of the wind tail. See below.


Zero knots / Indeterminate Wind Direction

Wind direction

Wind direction

Wind direction

Wind direction

1 x Short Barb = 5 knots

1 x Long Barb = 10 knots

1 x Pennant = 50 knots

2 x Long Barbs, 1 x Short Barb = 25 knots



Using GRIB files

Where can I get GRIB files?

GRIB files are widely available, most standard resolution data is free to

the user with the exception of communication costs.

There are three basic methods of getting a GRIB file,

different methods are used by each provider:

• Website. Straight-forward area list or interactive map

tool to download the region you require

• E-mail services. Developed to be very efficient

on data use. The user sends an e-mail that contains

specific codes for the data they require and receive

an e-mail with GRIB file attachment in return –

useful for smartphone use

• PC based client programs. These usually works

in a very similar way to a browser based tool, but

as you already have the program installed there is

less to download (only the GRIB file itself ) so is

faster and saves on communication costs. Some

client programs also include a compression tool to

further save on data cost.

UGrib Software

zyGrib Software

Free GRIB Sources











period (days)

Other features Yes Yes Yes 0.5º 3,5,7

Website or PC Client software. Includes file compression and max file size

tools for low bandwidth applications Yes Yes Yes 1.0º 15 (max)

E-mail request service – originally designed for low bandwidth

applications – can be used from smartphones Yes Yes Yes 1.0º 3 Yes Yes Yes 0.5º 3

*Correct at time of going to print



Higher resolution GRIB forecasts are available, these are usually subscription based services. Data is generally

from a very high resolution localised model and/or has been subjected to some form of post processing of the

raw GRIB data.

High Resolution GRIB Sources











period (days)

Other features Yes Yes Yes 0.01º 1,3,5 Requires client software – available from PredictWind Yes Yes Yes 0.02º 1,3,6 Also supply free 0.5º GRIB data

Loading GRIB files onto Zeus

Up-to-date GRIB weather files are easily loaded via a quick and

simple process.

*Correct at time of going to print

• Download a file from your chosen source, save it

to a USB stick

• Insert the USB stick containing the file into the

USB port on the front of the Zeus unit

• Copy the file to Zeus via the Files option under Pages

• File transfer is also possible via Memory Card.

Transfer with a USB stick

Smartphone transfer


Many modern smartphones can receive GRIB files

via email, or by using their web browser, and save

them to the phone memory. In many cases the

phone will act as a USB drive if connected to the

B&G Zeus.



Sailing Overlay

What does the Sailing Overlay do?

B&G’s Zeus is the first and only chart plotter developed specifically for sailing.

The unique Sailing Overlay allows the display of navigation information

designed to aid the sailor in determining the tidal effects on the boat and the

best position to tack or gybe to reach a waypoint or clear a headland.

Data displayed in the Sailing Overlay includes:

• Through-Water and Over-Ground vectors show the

effect of tide and leeway on your course

• Mark and Boat Laylines, which help the skipper

easily assess whether the boat will be able to clear a

headland or obstacle on its next tack. Laylines can

be corrected for tidal flow

• Recent min/max layline positions allow the

navigator to make a safe decision to tack for a

headland or waypoint in shifting winds, based on

the recent variation in wind direction

• Time and distance to layline information is

provided for each tack, allowing preparation time

for manoeuvres.


Are you always being asked,

“how long until we tack?”

Display “Time To Layline” in the

data bar so you can always know

the answer to the question.

What other information is available?

The data bar at the top of the chart screen can be

configured by the user, allowing the selection of any

Zeus system data.

As part of the part of the process for displaying the

laylines, information regarding time and distance

to the layline is calculated. This information can be

displayed in the data bar, and prove invaluable when

asked “how long until we need to tack?” or if you wish

to stay a certain distance from the coastline

The Heading Extension line allows the user to see if

they are achieving the Target True Wind Angle.



What are laylines?

In simple terms, laylines represent the most efficient

way of reaching your destination, given the present

wind conditions – by sailing along your target laylines

you can maximise your Velocity Made Good (VMG).

• “Mark Laylines” display the target course to sail to

reach the destination

• “Boat Laylines” display the target course of

the yacht.

The point where the two sets of laylines intersect can

be thought of as the tack (or gybe) point.

Zeus also offers the ability to correct laylines for the

effects of the current tide measurement.

How do laylines work?

Laylines are based on the True Wind Direction (TWD)

from your instrument system along with either (a) your

target upwind and downwind sailing angles or (b) your

actual sailing angles.

Target angles provide you with the most efficient

sailing angle, while actual angles use real data from the

live measurements.

• Targets are set by either entering your upwind

and downwind sailing angles into Zeus, or they can

be provided automatically from a Polar Table

equipped H3000 system (Hercules Performance or

Hercules Motion)

• Actual data uses your current True Wind Angle.

What can I see?

Boat vectors (blue line)

• Vectors show predicted

position of boat at a

future time

• User set based on distance

or time

• Select from Water vector

(Heading/Boat Speed),

Ground vector (COG/SOG) or

both – allowing the navigator

to assess tidal effects.

Boat laylines (solid lines)

• Starboard (Green) and Port

(Red) tack

• Laylines use Manual, Actual

or Polar Targets (H3000

Hercules Performance or

Motion only)

• Tidal correction available.

Mark laylines (solid line)

• Indicate tacking point to

make the waypoint

• Tidal correction available

Min/Max laylines

(dashed lines)

• Indicates the best and worst

case layline positions

recorded in recent data

(manual user reset available)

• Allows the navigator to make

an informed decision on a

“safe” or “risky” call to tack

on a layline.



Zeus provides the user with three options:


Should be selected if you do not

have an instrument system that

can send polar target information

to the Zeus system but you want

to sail to a target wind angle.

Manual Laylines allow the user to

preset the upwind and downwind

sailing angles for the boat. Target

angles vary by boat and conditions,

but angles of 45º upwind and

165º downwind are a good

starting point.


Are incredibly useful for cruising

yachts, where the focus is more

on tacking in the right place to

clear obstructions to stay safe

rather than sailing at optimum

performance all the time. In this

mode the laylines are calculated

from the current True Wind Angle,

either directly from the instrument

system if available or calculated

from Boat Speed and Apparent

Wind Angle. This setting gives you

a realistic tacking angle based on

your current performance.


Are based on the upwind and

downwind Target True Wind Angle

from the Polar table stored in

compatible instruments. It is also

possible to display the Target True

Wind Angle in the data bar.

All types of layline can be

corrected for tidal flow.

Tidal Correction

Zeus offers the user the ability to correct the laylines

for tidal effects. Unlike PC based chart plotters,

which often use tidal models to predict tidal effects

along your entire route, the B&G Zeus uses the live

instrument data to calculate the tidal effect on the

boat, and applies this information to the laylines.

This means the user does not have to worry about

updating the tidal model.

In the screenshots opposite we can see the difference

between laylines with tidal correction applied, and

those without tidal correction applied.




= Current Rate

and Direction

In this example we can see the boats “through the

water” performance and compare it with its “over the

ground” performance to calculate the measured tide

rate and direction.

Boat Speed 9kts Heading 042°M

SOG 7kts COG 047°M

Tide Rate 2.12kts Tide Direction 239°M



If the yacht is tacked according to the laylines in image 1, it would not make the waypoint,

due to the adverse tide – at least 2 more tacks would be required. In image 2 we can see

that the laylines have become wider to account for the tide, tacking on these laylines will

help ensure the yacht makes the mark.

1. Laylines without tidal correction 2. Laylines with tidal correction

Heading, Leeway and Course

Heading is the direction that the yacht is pointing

as you sail through the water. This is not always the

actual direction your are travelling through the water –

due to leeway.

Leeway is the angle that the boat slips sideways,

relative to the direction it is pointing.

We refer to the angle that we actually travel through

the water (heading + leeway) as “Course”. Course does

not include any tidal effects as it is measured relative to

the water. The difference between Course and Course

Over Ground is caused by tides or currents.

On advanced instrument systems, like B&G H3000,

it is possible to calculate Leeway and correct the wind

data for this value, on less advanced systems the

leeway value is not available so calculation is based

only on Heading.


In addition to tide, remember that windshifts will

affect your ability to make waypoints, familiarise

yourself with the limit layline feature to judge

how likely a windshift is to prevent you from

making your waypoint.



Time Plots

What is a Time Plot?

Time plots allow you to graph the data that is being sent to your B&G

Zeus from the instrument system.

There are two standard layouts for Time Plots

in Zeus:

• Layout 1 displays 4 Time Plots alongside the Wind

Plot (Boat Speed, AWA, TWA)

• Layout 2 displays 3 Time Plots alongside the Wind

Plot (Depth, TWA, Boat Speed, VMG to Waypoint).

The user can change between layout 1 and 2 and edit

the data in each layout.


Look for correlations between changes in wind

speed and changes in wind direction - if you

know that an increase in wind leads to a 10

degree windshift you can prepare for it.

What is a Wind Plot?

A Wind Plot is a special type of Time Plot specifically

designed to help you understand recent changes in

wind speed and direction, this is generally referred to as

wind trend. While normal Time Plots display horizontally,

Wind Plots are configured vertically with the newest

data being displayed at the top of the screen.

By showing the data in this format Wind Plots show

changes in wind direction in an intuitive way – if the

wind is shifting to the right, so is the graph.

Alongside the wind direction is the wind speed, this

enables you to correlate the changes in direction and

speed – does the wind tend to shift to the right in

gusts? Here you can see.

What can I see?

Historical data (green line)

• The green line plots the data from the

instrument system

• The user can select which data to display.

Time periods

• For each Time Plot or Wind Plot the user

can set the time period shown

• Default period is 10 minutes

• User options are 5, 10, 30 and 60 minutes

• Barometric pressure up to 48 hours.



B&G Zeus

The only


designed for


View and predict vital

weather information.

Port and Starboard coloured

Laylines indicate when to

safely tack or gybe.

Water and ground vectors

show the effects of tide

and leeway.

Makes your B&G instruments

quick and easy to calibrate.

Also compatible with other

instrument systems.

Find out more at




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