Can you
explain the differences in the forward scans?
In
the FORWARD VERTICAL SCAN, the scanning beam is pointed directly
forward of the boat. The beam begins just below the water surface and sweeps to
straight down. This creates a view which shows the entire water column and bottom
contour in the path of the boat. The Forward Vertical Scan and down-looking are
done with a single transducer with no moving parts. By
rotating the phased array 90° we allow the system to perform a FORWARD HORIZONTAL
SCAN. The scanning beam sweeps from either 45° port to 45° starboard or
90° port to 90° starboard. The center of this beam is angled downward at 10° to
avoid surface 'noise' and allow the beam to scan the bottom.
The
iScan V90 performs a Forward Vertical Scan as well as traditional down-looking.
The
Color Twinscope performs a 90° Forward vertical Scan and adds a 90° Forward horizontal
scan, along with the traditional down-looking view.
The
iScan 180 is able to scan in a Forward Vertical manner and uses twin thru-hull
transducers to increase the Forward Horizontal Scan to a full 180°. This is advantageous
for boats with a deadrise angle greater than 9° or with a keel that would block
the Forward Horizontal Scan of the Color Twinscope. For fishing, this provides
the greatest scanning area. For navigational safety, this creates an increased
ability to scan the sides of channels or track along underwater hazards such as
reefs. Like all other Interphase Forward Scanning Systems, the iScan 180 also
provides traditional down-looking.
Index
What
are the different types of forward scans used for?
The
FORWARD VERTICAL SCAN is most often used for NAVIGATIONAL SAFETY. This scan sweeps
through the entire water column and displays bottom contour directly in the path
of the boat. By using this scan, it is possible to observe shallow conditions
ahead of the boat and to judge if the shallows present a danger to your boat.
Alternate
uses for the FORWARD VERTICAL SCAN include, but are not limited to:
Bass
Fishing - Attach the transom mounted transducer to a trolling motor mount and
sweep a large area. This is a good technique for finding bottom contour over which
bass feed. Shipping Containers, Whales and Iceberg Detection - The scan can be
adjusted to scan near surface only. Our products are used by circumnavigators
to avoid collisions with hazards even in the deepest waters.
The
Forward Vertical Scan is available in the PROBE, ISCAN V90, COLOR TWINSCOPE and
ISCAN 180 products.
The
FORWARD HORIZONTAL SCAN is most popular for fishing. This scan allows fishermen
to sweep a sonar beam through the water ahead of the boat and then steer to fish
and schools of bait fish. Our forward scanning sonar has been used for everything
from marlin fishing to tuna to searching for squid. The beam is angled downward
at 10 degrees, allowing it to scan the bottom. This is useful for following a
ridge or other bottom feature to find fish.
In
addition to fishing, the FORWARD HORIZONTAL SCAN is also used in conjunction with
the Forward Vertical Scan for navigating. The Forward Vertical Scan can indicate
a hazard directly in front of the boat. Small boats can maneuver to scan the bottom
around the hazard. Larger vessels find the Forward Horizontal Scan useful for
looking at the rise and fall of bottom contour. Once a hazard is detected in the
Forward Vertical Scan, one can switch to the Forward Horizontal Scan to judge
if it is possible to navigate around a hazard. The Forward Horizontal Scan can
also be used to scan the sides of a channel or harbor entrance. The iScan 180
provides a 180° horizontal scan and is best suited to this application.
The
Forward Horizontal scan is available in the COLOR TWINSCOPE (with a 90° scan)
and the ISCAN 180 (with 180° scan).
Index
How
do I know if I am scanning fish or the bottom?
The
Forward Horizontal Scan intersects with the bottom at approximately 5X water depth
forward of the transducer. If you are in 100 feet of water, adjust the forward
range to 600 feet (the closest forward range GREATER than the expected intersection).
This way you can know that you should be scanning the bottom. In the iScan series,
stronger returns are indicated by stronger colors (red, yellow) and weaker returns
are indicated by weaker colors (green, blue). The scale on the display provides
examples of the 12 possible colors in the range of returns. Hard, rocky bottom
produce stronger returns than soft muddy or sandy bottoms. Once you know you are
scanning the bottom, then returns between the bottom and the transducer can be
understood to be in the water column. Must suspended objects in the water column
are fish. Note that a protrusion such as a submerged piling can also be scanned
in the water column. Learning the difference between a piling and a marlin is
a matter of knowledge and experience.
The
Forward Vertical Scan has a very intuitive display. The bottom typically appears
as a 'slice' out in front of the boat. Once you have located the bottom, any return
above the bottom is in the water column.
When
learning to use forward scanning sonar it is best to go to an area where you are
already familiar with the bottom features. Play with the controls of your forward
scanning sonar to learn how various features appear. This will aid you when you
are in unfamiliar conditions.
Index
Index
Can
I install a thru-hull transducer on my aluminum boat?Yes.
The transducer body is composed of urethane plastic. This will not promote galvanic
corrosion. The fairing block that Interphase makes for our thru-hull transducers
is also plastic. The thru-hull stem is bronze. After installation, the stem must
be isolated from the hull to prevent galvanic corrosion. Several methods can be
used or combined to isolate the stem. Some examples include; sealing the base
of the faring block inside and at the top of the fairing block with silicon sealant,
placing PVC over the stem and sealing the base of the PVC, sealing the base of
the stem and covering the stem with heavy-duty shrink wrap. Other methods can
be utilized. See your professional transducer installer for further recommendations.
The important factor in installation is to isolate the stem from the aluminum
hull. If the stem and hull are isolated from each other, galvanic corrosion cannot
occur.
Index
How
large of an area does the scanning beam cover?The
angle of the scanning beam is approximately 12°. You can estimate the diameter
of the beam by dividing the forward range by 5. Example: if the forward scanning
sonar is scanning 100 feet forward, the diameter of the beam at 100 feet is approximately
20 feet. If you are sweeping the beam over 90°, the beam will be 20 feet in diameter
at 100 feet for the entire 90° sweep. If you are performing a Forward Vertical
scan and the bottom was less than 100 feet deep, then the diameter of the beam
would change as it scans the bottom. Example: You are scanning 200 feet forward
while in 75 feet of water. Near the surface, the beam diameter is 40 feet. Directly
beneath the boat, the diameter of the beam (at the bottom depth of 75 feet) is
15 feet.
Index
When
in water less than 20 feet, an arc appears on the screen from the surface to the
bottom. It remains at a consistent forward range. What is this arc?The
arc is a SIDELOBE. It appears at the same forward range as the depth. All sonar
beams have sidelobes. These are weak sonar beams that project out from the sides
of the main beam. In traditional down-looking sonar, sidelobes reflect away from
the transducer and are not detected. In forward scanning sonar, the beam is horizontal
to the bottom, allowing the sidelobe beam to reflect off of the bottom and back
to the transducer. In shallow water, weak sidelobe beams create a strong enough
return to be detected. They create a distinctive arc shape. See the Interpretation
Section of your operations manual for a drawing of a sidelobe. Sidelobes also
appear on radar images. It is possible to recognize sidelobes and learn to mentally
'filter them out'. In water less than 20 feet deep it is not usually possible
to lower the gain to the point of removing the sidelobe without losing bottom
depth as well. Reducing gain will reduce the sidelobe, but be cautious not to
lower the gain below where the system can acquire a reliable depth reading.
Index
Why
can't I see fish when I have the GAIN in the AUTO mode?The
unit sets the Gain based on down-looking returns. If the bottom is a hard rock
bottom, then the system will adjust the Gain downward to prevent strong returns
from cluttering the screen or creating bottom multiples. This adjustment may 'screen
out' weaker returns such as those created by fish.
When
encountering a soft bottom, the Gain will be increased to provide consistent depth
readings. If large schools of bait are present, the system may temporarily 'lock
on' to these schools and present their depth as the bottom depth. It may be necessary
to reduce the Gain to prevent false depth readings.
No
single gain setting is appropriate for all situations and needs. Some boaters
prefer to never allow the system to adjust the Gain Automatically. This is because
they want to know if they are over a rock bottom or softer bottom, or scanning
weeds or a coral head. If the unit adjusts Automatically, it may be more difficult
to determine the density of the bottom because the system is always adjusting
to provide the optimum bottom reading. While Auto Gain can be a helpful tool,
sometimes manual adjustments are more appropriate to an individual's needs, application,
or local water conditions. Just as the cruise control in your car is helpful during
long trips on the freeway, you wouldn't use it in town.
Index
As
the bottom depth approaches the depth range, the depth reading become less consistent.
How can I adjust for this?Adjust
the STC. All Interphase sonar systems utilize a technology know as Time Variable
Gain (TVG). As the depth increases, the unit internally increases the gain. As
the system approaches the maximum current depth range, it may adjust the gain
high enough for it to detect particulate matter in the water. This is more likely
in dense or murky water. This can produce erratic depth readings much more shallow
than the actual depth.
STC
stands for Surface Time Constant and can be used to force the system to ignore
'noise' near the surface for the purpose of acquiring depth readings. This does
not effect near surface returns in the forward scan. You can adjust the STC to
a desired depth, promoting consistent depth readings. Because the amount of gain
used by the TVG circuits varies depending on depth and bottom hardness, the STC
can be adjusted for each range. It may not be necessary to make an STC adjustment
in every range.
Index
What
do fish look like in the forward scan? Are there fish symbols?
Because
forward scanning sonar is true sonar, we do not create artificial fish symbols.
Our sonar systems are used for research, search and rescue as well as fishing
and navigational safety. Therefore, we try to produce the most accurate returns
possible to provide the highest quality of sonar information to the wide variety
of applications of our products.
Fish
appear differently on forward scanning sonar than they do on traditional down-looking
fish-finders. When any sonar 'pings' a fish, the sonar signal reflects off of
the air bladder of the fish. This is how professional tournament fishermen are
able to tell different species of fish on their fish-finders. They recognize the
pattern of the air bladder in particular fish. A down-looking sonar strikes the
fish along the spine and the air bladder can then produce a 'fish arch'. Fish-finders
that display fish symbols look for this arch and any other suspended returns and
display them as fish, whether they actually are or not. With forward scanning
sonar, the fish may be 'pinged' from a variety of angles. If the fish is swimming
away from or toward the transducer, then it does not create a very strong return.
This is because the area of the air bladder presented to the sonar beam is very
small. The same fish, swimming across the sonar beam, can produce a very strong
return because it is presenting the maximum area of the air bladder to the sonar
beam. Therefore the same fish may show up as a much stronger or weaker return
than when it was detected from directly above.
Schooling
fish show up as varying densities of 'cloudy' returns. The density depends of
the size of the fish and how tightly packed the school is.
Keep
in mind that while our forward scanning technology is unique, we are utilizing
a standard sonar beam. This beam detects fish in the same manner as any down-looking
fish-finder. Our technology simply allows us to scan forward, so that you can
detect fish and approach them ready to go, rather than scattering them as you
pass overhead and trying to find them again.
Index
I've
seen 2 types of thru-hull transducers for the Color Twinscope, 1 with single transducer
and 1 with dual transducers. What are the dual transducers for? Do they provide
an extra function for the display or is it to offset a larger keel? Does a large
keel affect the horizontal sweep of the sonar (single or dual)?
We
offer the twin thru-hull transducers for small high speed boats. The single thru-hull
transducer is twice as wide as each of the dual thru-hulls. If the boat does no
allow an installation on or close to the center line, then the transducer is sometimes
placed 2-3 feet away from the center line. On a high speed boat (40+MPH) the drag
can be felt in the steering. If the boat does not have trim tabs to trim this
out, then the boat can 'pull' to one side at high speeds. The dual transducer
configuration allows for a transducer on each side of the hull which evens out
the water flow across the hull.
This
does not account for the forward horizontal sweep being blocked by a keel, or
deep V hull. In order for the forward horizontal scan to pass beneath the hull,
the angle between the transducer and lowest point on the hull must be less than
10 degrees.
If
the transducer(s) cannot be mounted in such a way as to allow the Forward Horizontal
Scan to sweep under the hull, then the iScan 180 should be considered. The iScan
180 uses twin thru-hull transducers to perform a 180° Forward Horizontal Scan
without keel or hull interference.
Index
Can
I detect object floating on the surface, such as logs or pallets?Objects
floating on the surface are masked by 'surface noise' or aeration at the surface.
Wave action and boat action create this aeration. The depth of aeration varies
depending on conditions. Sonar reads air as an object. This is how fish-finders
function. They do not see the body of a fish, but rather the air bladder of the
fish. Hence, any object in the aerated water near the surface is masked by the
surface aeration. An object must protrude down below the surface aeration in order
to be detected. A deadhead, where most of the tree sticks down below the aeration,
can be detected, but a log floating horizontally on the surface is masked by the
surface noise.
Objects
such as shipping containers, icebergs, and sleeping whales can be easily detected
by Forward Scanning Sonar. The Forward Vertical Scan is used for this application.
Index
How
fast can I go and still operate my Forward Scanning Sonar?
The maximum speed
has to do with 2 factors:
1.
Boat performance: The transducer can send and receive as long as it has smooth
flowing, non-aerated water across the send/receive surfaces. We have talked to
boaters with small boats that lose the sonar signal when they come on plane at
10 knots. We have talked to other boaters who have a usable signal at 30 knots.
It depends on boat performance and transducer placement.
2.
Forward range/depth versus speed: The maximum forward distance is about 5-6X water
depth forward of the transducer. If you are running in 20 feet of water, then
your maximum forward range would be about 100-120 feet. At 30 knots, this is probably
not enough warning to make the unit an effective tool. If you are moving slowly
into an area that is of concern, then the unit can be effective. Deeper water
can give you greater distance and increased warning time. The maximum forward
range is 1200 feet.
Special
note: The minimum effective operating depth is 10 feet.
Index
When
operating in shallow water, how far ahead can I scan?
The
maximum effective forward range is approximately 5-6X water depth. Thus, in 15
feet of water, the maximum forward range would be about 75-90 feet. At 25 MPH
this would not provide enough warning time to avoid collision. However, when operating
in shallow water, the prudent boater will be traveling at low speed. Forward Scanning
Sonar is usable for navigating channels and other shallow areas. In fact, it is
most often used for this application, keeping in mind that the product is designed
to keep a boater out of shallow water, but is not typically used to navigate once
in extremely shallow water.
The
minimum effective operating depth of the Forward Scanning Sonar System is 10 feet.
In water less than 10 feet forward scanning sonar may show false returns or fluctuating
depth readings. Note that most planing hulls aerate the transducers at planing
speeds, rendering them inoperable.
Index
Is
the Color Display sunlight viewable?
Yes.
Our color displays utilize bright backlighting combined with specialized filtration
to provide clear viewable images, even in direct sunlight.
Index
What
type of transducer is right for my boat?
The
first line of inquiry should be about the boat. Transom mounted transducers are
intended for low speed boats with external props. Boats with inboard motors and
boats that regularly exceed 40MPH (35 Knots) cannot use transom mounted transducers.
Inboard motors create aeration and excess turbulence that prevent the transducers
from operating properly. I/O motors where the prop is aft of the transom do not
create this situation. Be careful that the driveshaft of the I/O does not block
the forward horizontal scan. Boats that exceed 40MPH run a risk of having the
transom mounted transducers torn free of the transom. The transom mounted transducers
are not designed to be used at these speeds and should not be mounted on boats
that operate above 40MPH.
In
addition, the transom mounted transducers are mounted on kick-up brackets. This
allows the brackets to kick up at about 35-40MPH. This is intended to allow the
transducers to kick-up if they strike an object, or to be pulled up when trailering
a boat. Once kicked up, the transducers must be manually reset in order to function.
Thru-hull
transducers are for boats that exceed 40MPH and /or have inboard motors.
Note
that the 180° Forward Horizontal Scanning products are only available with twin
thru-hull transducers.
Index
Where
do I place the transducer?
Keep
in mind the primary rule for transducer operation. This is: the transducer can
function as long as it has an unobstructed forward view and has smooth flowing
non-aerated water surrounding it. Transducer placement depends on boat size, speed,
hull configuration and sonar application.
On
displacement hulls, the transducer is generally located 1/3 -1/2 aft of where
the bow meets the water line. The transducer should never be mounted more than
1/3 aft of where the bow meets the waterline. It is important that the transducer
be below turbulent aerated water created by the bow.
On
sailboats with a fin keel, the transducer is most often placed forward of the
leading edge of the keel though it is sometimes faired into the keel. As this
location may be where the sling rests when hauling the boat, the transducer may
be placed on either side of the hull with the foremost face of the transducer
even with the leading edge of the keel. Alternately, the transducer may be placed
forward of the keel ahead of the lifting strap location. This should not be forward
of 1/3 aft of where the bow meets the waterline.
On
planing hulls the transducer is typically placed near the transom. This is to
provide smooth flowing water at the highest speed. However, most planing hull
boats create transducer aeration when on plane regardless of transducer location.
It
should be noted that thru-hull transducers can effect boat performance in two
important ways. The first concern is cavitation created by the transducer that
causes reduced engine performance by disrupting water flow around the propeller.
This is smoothed out by the hull in some boats, but on planing hulls with the
transducer near the transom, the hull is not able to clear the cavitation. The
second concern is uneven drag on high-speed boats. This may occur when the thru-hull
transducer is mounted far off of the centerline of the boat. At low speeds and
on large boats the effect is negligible. On smaller boats at high speeds the drag
can effect the steering. The effect increases as the boat's speed rises. Boats
with trim tabs can usually trim this out, but boats without trim tabs may feel
a pulling sensation toward the transducer side of the boat. For this reason it
is recommended that the transducer be installed on or close to the centerline
of small high speed boats.
A
less intuitive mounting location for the thru-hull transducer on a planing hull
is on the centerline just forward of midship. The goal in this mounting is to
place the transducer so that it is out of the water at planing speed. As most
transducers are aerated at planing speeds, this removes the transducer from the
water flow preventing cavitation and steering problems. Most applications for
forward scanning sonar occur when the boat is at low non-planing speeds including
fishing and navigating hazardous waters. Under these speed conditions the transducer
is in the water. Note that the transducer should not be operated when it is out
of the water.
On
trailered boats, be certain that the mounting is such that the boat does not rest
on the transducers. This could result in damage to the transducer and/or boat
hull.
Explore
possible mounting locations while the boat is on the trailer.
Index
How
do I get speed and temperature on my Forward Scanning Sonar?
The
Color Systems accept NMEA speed from a GPS. They also accept water temperature
information from a NMEA source. A NMEA speed/temperature transducer is not available.
The Monochrome
Systems utilize an analog speed/temperature transducer. Both transom mounted and
thru-hull transducers are available.
Index
What
split-screen views are available on my Forward Scanning Sonar?
You can view either the Forward
Horizontal Scan or the Forward Vertical Scan in a split-screen mode with the traditional
Down-looking view. You can also view either Forward Scan along with the Data View
in split-screen. It is not possible to view both the Forward Vertical and Forward
Horizontal Scans in a split-screen mode. The two scans would interfere with each
other.
The Data
Mode features large digit depth, lat/lon and water temperature in a split-screen
with any forward view.
Index
Can
I use my Forward Scanning sonar as a depth-sounder and fish-finder?
Yes.
All Interphase Forward Scanning Sonar systems include a traditional down-looking
view and digital depth directly beneath the transducer. The down-looking view
can be operated as a split-screen or full screen view. Many features of traditional
fish-finders are available in the full screen view such as Zoom.
The
digital depth is always displayed regardless of scanning mode. Large depth numbers
are available in the split-screen Data Mode.
Index
Can
my Forward Scanning Sonar output data to other instruments on my boat?
Yes.
The Color Systems output NMEA Depth data.
Index
When
operating the Forward Horizontal Scan, how can I tell how deep a return is?
The
Color Systems have a unique CURSOR function. You can place an on-screen cursor
on any return and a data box will provide the Depth, Range and Bearing of the
center of the beam at that location. If the return is a school of fish, then you
will know that there are fish at that depth, range and bearing. If the return
is a rock pinnacle, you know that the pinnacle extends up AT LEAST to this depth.
The pinnacle may extend above the beam. For detecting the height of returns the
Forward Vertical Scan is best.
The
on-screen cursor can also be activated in the Forward Vertical Scan. The corresponding
data box will provide range and depth at the location of the cursor.
Index
What
do the colors mean on the Forward Scanning Sonar?
The
colors indicate STRENGTH OF RETURN. In the iScan series, stronger returns are
indicated by stronger colors. Each Forward Scanning Display has a Color Scale
to assist in understanding the strength of the returns you see on the screen.
The scale ranges from Dark Red through Yellow to Light Blue. Red returns are the
strongest returning signal. The scale on the display provides examples of the
12 possible colors in the range of returns. If the Gain is adjusted properly,
the colors can provide an indication about hardness or density of a sonar return.
At the same depth, a soft mud bottom provides weaker returns than a hard rock
bottom. At the same range, a metal container provides a stronger return than seaweed.
Note that color does not indicate depth. A protrusion such as a submerged piling
can also be scanned in the water column. Learning the difference between a piling
and a marlin is a matter of knowledge and experience.
When
the Gain is in the Automatic mode, it adjusts for the best down-looking depth
reading. This may change the strength of returns. Be sure to note the gain when
judging the strength of returns.
Index
Can
the display be mounted in-dash?
Yes.
The iScan Color Series displays come with a Quick Disconnect Mounts (QDM) as well
as hardware for mounting in-dash. The QDM is convenient for boaters that wish
to remove their electronics during winter storage or when docked in areas with
poor security. Each system comes with a cut-out to allow your installer to install
the display in-dash. When mounting in-dash, remove the lower half of the QDM.
The upper half of the QDM contains the contacts for power and I/O communications.
Index
The
30 foot transducer cables from my transducers are not long enough to reach my
display. Can I extend the cables?
Yes.
We carry 30 foot extension cables. A maximum of one extension may be used. The
cables should not be extended beyond a total cable run of 60 feet. If you extend
the cables and have a Remote Station, then the total cable run to the Remote station
would be 90 feet. This exceeds the maximum recommended transducer cable run. The
Remote Station would suffer from a loss of approximately 15% of signal.
Index
Can
I operate a Second Station?
Yes.
Interphase Forward Scanning Color Systems may be attached to a Remote Station
Kit that includes a second display, power Quick Disconnect Mount and 30 feet of
cable to go from the Master to Remote stations. The remote station kit allows
for one button control of either the Master or Remote station.
Index
Is
Forward Scanning Sonar difficult to operate?
The
Forward Vertical Scan is very intuitive and most boaters learn the basic operation
and interpretation quickly.
The
Forward Horizontal Scan takes more time to learn due to the downward angle of
10 degrees and the interpretation of an unfamiliar view.
We
suggest that you take the system to an area where you are already familiar with
the bottom conditions and then spend some time playing with the different settings
and scanning modes. For initial operation it is best to explore in 20 - 50 feet
of water depth. This will allow for strong returns. Once you become familiar with
interpreting bottom conditions that you are familiar with, it will be much easier
to interpret unfamiliar conditions. Expect to spend a little time learning the
operation and interpretation of the system. Users who do so report that they find
our products valuable for their boating needs. How valuable? See our Feedback
page.
Copyright © 1998-2006
Interphase Technologies, Inc. All rights reserved.
