Lowrance StructureMap HDS Gen 2 User manual

“The single biggest mistake made by fishfinder
owners, is a lack of confidence.”
– John ‘Fishton’ Easton
Firstly I would like to thank you for purchasing this book, and to
all of you who bought my first book and then inspired me to do
another. There is a lot of truth in the saying - “Everybody has a
book in them, but very few have a second.”
The first Fisherman’s Guide to Sonar was primarily an extension to
the user manual and installation guide. A common mistake made
by many in this high tech fishing industry. There is no replacement
for the user manual, please read it at least once if you are
unfamiliar with the Lowrance range that you have bought. This
book is very different as it deals more with Sonar Performance,
getting the very best out of your investment.
The single biggest mistake made by fishfinder owners, is a lack of
confidence. Sure, in some cases it is justified, like the extreme case
of the chap who recently posted a picture on social media of his LSS
transducer mounted upside down with a caption - “Can anybody
help as I am getting no readings on my DownScan?” Inmost
cases though, it is simply a small tweak, or a lack of confidence not
only in the equipment but in ones self. I recently experienced this
frustration myself as I just couldn’t get the results another user was
getting using the same equipment. I simply had to accept that our
conditions and targets are vastly different for the specific
application at the time, and there was nothing wrong with my
installation or setup. This is why a mental reference is so
important when it comes to sonar, and it’s not just dirty fresh water
that can give poor sonar results but crystal clear ocean water with
an abundance of micro organisms will offer the same challenges.
In these cases we simply need to learn how to make the best of a
bad situation, and not get disheartened when we don’t get those
picture perfect returns.
Having said that, one needs to make sure that your equipment is
installed correctly, and you know how to test if it is in fact installed
perfectly or not. In most cases where I have come across a poor
installation / setup, it has been on the ‘good advice’ of a fellow
angler who has, in his own words - “Been using
sonar all my life.” Unfortunately, he has
obviously been doing it wrong all this time,
and how many other people has he led into
the dark?
I trust you will enjoy this second edition of
Fisherman’s Guide to Sonar and look forward to
getting some feedback from you, good or bad.
The Author - John ‘Fishton’ Easton
ii
• Foreword •

6
Google Earth
(Windows/Mac/Android)

8
SketchUp Mobile Viewer

14
Cone Size / Frequency
1. I have never understood why the
deep penetrating frequencies
such as 50kHz typically have
a wider cone and the shallow
water 200kHz a narrow cone.
2. The reason I say this is because
in deep water the coverage area
is already quite large due to the
distance from the transducer,
so a wide beam is not that
essential - in fact, you want it
to be quite small in order to get
detail and target separation at
great depths.
3. Whereas the 200kHz for
shallow water should be as wide
as possible due to the much
shorter distance from the
transducer.
4. This is emphasized further
when trolling, even when the
actual depth is >1000ft.
The Sound Wave
Tip: Take care when choosing the right transducer/s for your fishing style.
Airmar P66

27
The Transducer
HDI 83/200kHz
HDI v.s TM150(CHIRP)
Several frequency options were used but the
basic settings remained the same.
The TM150 came out on top in all cases.
Airmar TM150

29
The Transducer
Shallow (<100m/
300ft) Transducer
Properties
1. This depth range is by far
the most popular as it
includes everything from
Largemouth Bass on flats in
less than 10ft on Inanda
Dam, trolling for Salmon on
the Baltic sea to Amberjack
around old ship wrecks in
300ft off the Florida Keys.
2. The Lowrance HDI, Airmar
P66 and TM150M
transducers are certainly the
most popular transom
mount transducers.
3. Taking the transducer
properties into consideration,
it is easy to decide which is
the best transducer for your
style of fishing.
Tip: Gen3 owners - If the majority of your fishing is done deeper than 50m/
150ft it will be in your best interest to start considering the B175 range of
transducers. In less than 150ft the TM150 will outperform the B175.

36
Transducer Selection
Deep Water Trolling (Ocean)
Fitting an offshore boat for deep water trolling, a
good idea is to fit two units in order to get the
benefit of two sonar sources:-
1. Display #1 - for charts and narrow beam
50kHz/High CHIRP to track the bottom using
a TM260 transducer (19°/50kHz) for example
2. Display #2 - for 83kHz/Medium CHIRP and
StructureScan (DownScan and SideScan) to
track bait and fish in my trolling depth only*
using an LSS-2 and a TM150 transducer
The Transducer
TM260 Display #1
Display #2 * - Max Depth Range of Lures + 50%
LSS-2
TM150

41
Transducer Installation
Transducer Cable Shield
Electric Steer Trolling Motors
1. Use 12mm x 8mm polyurethane coiled air hose.
2. Cut off 4 coils for 42” shaft and 5 coils for 60” shaft.
3. Use a marker to dot the inside line where the hose will
be split. * VERY IMPORTANT*
4. Secure both ends of the hose to a table with clamps
with the dotted line facing up. Clamping two lengths
of timber to either side of the tubing will help stop it
from rolling when you cut.
5. Split hose along dotted line using a sharp lubricated
Stanley blade.
6. Clip over transducer cable and secure to motor shaft
starting at the bottom allowing the first coil free.
Tip: Lubricate transducer cable with WD40 and dip the hose in water before clipping over cable.

44
Transducer
Installation
The Water Test
Perfect Angle
Once all corrections have been
made for known angles, carry
out the ‘Tennis Ball Test’.
1. Cable tie a tennis ball about
6ft above the weight (might
have to replace with larger
weight) of your ‘H’ marker
buoy and drop into 20-30ft
of water.
2. Make a very slow pass right
next to the marker buoy
first on 200kHz and then
on 83kHz.
3. If your setup is perfect, your
display should look like the
video seen here. Tip: Do not attempt this test in windy conditions or strong currents.
005 tennis ball perfect

52
The Display
Display Resolution
1. Resolution is the number of vertical and
horizontal pixels your display is made up of.
2. Vertical Pixels (Height) - As we are dealing with
depth, it is obvious that vertical resolution is
important for traditional and DownScan sonar.
An interesting observation is that the Elite4 has
the same VP as the HDS9 Touch.
3. Horizontal Pixels (Width) - SideScan resolution
is dependent on horizontal resolution.
Horizontal resolution also plays a role in the
quality if the image when it comes to History
Resolution which is effected by boat speed and/or
display scroll speed.
Tip: Too many pixels on a physically small display can be just as detrimental as too little on a large display.

59
The Display
Option 2- Wiring Diagram
You will need: -
1. 1 x HDS7 Touch Gen3
2. 1 x Elite7m.
3. 1 x Elite7 CHIRP
4. 1 x N2k Starter Kit.
5. 1 x N2k ‘T’ piece and 2ft cable (see grey)
6.LSS-2 Transducer (StructureScanHD)
7.Airmar TM150 CHIRP transducer
8. Trolling motor adaptor for HDI transducer.
9. RAM Mount for 2nd Console unit.
Tip: You can also use the HDI transducer for CHIRP.

75
Chart Distance (83kHz <100ft depth))
1. Slow Cruise (20kph) = 960ft/292m
2. Fast Troll (10kph) = 480ft/146m
3. Idle Speed (5kph) = 240ft/73m
4. Trolling Motor (2.5kph) = 120ft/37m
2D Sonar in Perspective
Tip: These distances will be greatly
reduced when using 200kHz for example.
004 chart speed

79
Targeting Fish in Deep Water
Standing Timber
1. If the thermocline is a factor and at a
depth that you are comfortable fishing,
go looking for standing timber where
the tips stick through the thermocline.
2. Even if the actual water depth is 2 - 3
times what you would normally fish,
just look for bigger trees.
Tip: Start looking in areas where very steep banks or cliff faces are nearby.
The Thermocline
005 thermocline

85
SideScan Sonar
The Water Column
1. The water column does
not simply consist of
what’s directly beneath
the boat, but left to right
as well.
2. The deeper the water the
greater this area.
010 sidescan column

95
StructureMap - Hardware
1. Naturally you will need an HDS Gen2
or later with SideScan.
2. A perfectly mounted transducer which is
level, parallel to keel and with a clear
view to the left and right.
3. A good quality SD card no more than
8GB with a fast transfer rate.
4. An external GPS receiver such as the
Point-1 mounted as close to the LSS
transducer as possible for high accuracy
charts.
StructureMap

101
Species
Species will also determine the strength of the echo, as can be seen here in this comparison:
1. Carp - Very strong as they have the largest swim bladder, solid skull construction and large scales.
2. Tilapia - Next strongest echo due to a medium swim bladder, large skeleton and medium scales.
3. Largemouth Bass - The weakest echo due to a medium swim bladder, light frame skeleton and small scales.
Fish and Down Sonar
Tip: This is why
Largemouth bass are
so difficult to see on
SideScan sonar.

• CHAPTER 4•
SONAR DOCTOR

111
Sonar Ailments
* - This is the #1 solution to the problem of RF noise.
RF Interference - Trolling Motor
Try each of these possible remedies step by step
in the order they are here:-
1. Make sure all cables are in perfect order
and not damaged (especially section on
shaft of trolling motor), plug pins are not
damaged, dry inside and the plug itself
secure.
2. Make sure transducer and fishfinder power
cables are NOT neatly strapped to trolling
motor power cable in bow well.
3. Make sure Fishfinder and Trolling Motor
supply cables are not running in the same
loom from the back of the boat.
4. Earth Trolling Motor* fin to negative
(black) supply from battery going to
fishfinder with a small gauge wire
(2.5mm)
5. These steps should also sort out any
interference on the console units from the
main motor’s tachometer supply.
Earth lead to Trolling motor Fin

117
• Section 2•
DIY Test Kit
Build your own Test Kit
1. Multi Display Setup - 15ft Ethernet / N2k Starter
kit / Power cable / 12V 7Ah Battery
With this kit you can test everything from power, to
network to RF interference.
2. Single Display - Power Cable / 12V 7Ah battery and
N2k Starter kit if you have a Point-1.
Check power supply problems, RF Interference and N2k
issues if you have a Point-1 or other external receiver.
3. There are a number of Apps available that will help
you with testing your setup. Try the iNstall App by
Gemeco for a host of tools - https://itunes.apple.com/us/app/
install/id692762311?mt=8
Tip: Simply changing over head units with a fellow angler is the quickest way to test your unit.