Nasaco EML-2 User manual

ELECTRO-
MAGNETIC
LOG
DESIGNED AND
MANUFACTURED
IN ENGLAND
RoHS
2002/95/EC
EML-2

TARGET EM DISPLAY DRILL TEMPLATE

INTRODUCTION.
The EML-2 log consists of a through hull sensor and an interface box which, when
correctly installed, outputs boat speed through the water, trip distance and total
distance. The unit is factory set but has the facility for final in situ calibration.
The output, which updates twice a second, is in the NMEA-0183 format using the
sentences VHW and VLW. The trip distance is reset to zero each time the power is
turned off while the total distance is cumulative and cannot be reset. The EML-2 can
be used with the NASA Marine Clipper or Target EM log display or any other
compatible display.
The EML-2 log is designed for use in GRP hulls.
HOW IT WORKS.
The EML-2 generates an alternating magnetic field in the water below the sensor. As
the sensor passes through the water it generates an alternating electric field whose
amplitude is proportional to the boat's speed through the water. This field is detected
by small stainless electrodes on the underside of the sensor. The interface box then
amplifies this signal and converts it into speed and distance readings. An LED on the
interface box flashes each time new NMEA data is sent out.
CHOICE OF SENSOR LOCATION.
The sensor must remain in non-turbulent water flow at all times. Choose a position as
close to the centre line as possible where the water flow is unrestricted and where the
sensor is accessible for cleaning. Avoid areas around devices which could cause
electrical or magnetic interference.
Ideally the sensor should be: -
- close to the boat's centre line.
- as vertical as possible.
- clear of the keel.
- clear of sources of electromagnetic interference.
- always immersed, no matter what the heel.
- internally accessible for cleaning.
Page 1

INSTALLING THE SENSOR.
IMPORTANT: Read and fully understand the installation instructions and only
proceed if you possess the required skills and correct tools.
WARNING: Always wear safety glasses and a dust mask when installing to avoid
personal injury.
WARNING: Immediately check for leaks when the boat is put back in the water.
WARNING: The O-rings must be intact and, the lower one, properly lubricated to
make a watertight seal.
CAUTION: Never use solvents or products that contain solvents which could attack
the plastic.
IMPORTANT: The sensor in manufactured from glass filled nylon and is designed
for use on the outer skin of a fibre glass hull. Never install the sensor in a wooden hull,
since swelling of the wood could fracture the plastic.
Once a suitable location has been selected, with the boat out of the water, drill a 3mm
pilot hole from inside the hull. Using a 51mm (2.0 inch) hole saw, cut a hole
perpendicular to the hull from the outside of the boat. Using a file, make a small
chamfer around the hole sufficient to accommodate the 2mm radius on the skin fitting
flange. Now sand and clean the hole, inside and outside, to ensure the sealant will
properly bond to the hull.
IMPORTANT: Ensure the hull is of constant thickness under the skin fitting flange so
the nut will fit squarely against the hull.
Using a proprietary brand of marine silicone sealant, apply about 2mm of sealant
around the skin fitting flange where it contacts the hull and also up the sidewall to a
distance 3mm higher than the combined thickness of the hull, the spacer washer and
nut. This will ensure there is sealant in the threads to seal the hull and to hold the nut
securely in place. From the outside of the hull, push the housing into the mounting
hole using a twisting motion to squeeze out excess sealant. With someone outside
holding the skin fitting in position, from the inside apply a 2mm thick layer of sealant
around the hole equal to the diameter of the rubber washer. Then place the rubber
washer over the skin fitting and bed down onto the sealant. Coat the upper face of the
rubber washer with sealant and tighten down the nut taking care not to over tighten it.
(see fig1)
Page 2

Carefully remove all surplus sealant from the inside and outside of the hull and leave
until the sealant has cured. It is recommended that the area around the skin fitting is
thoroughly cleaned and the whole assembly be fibre glassed into the hull as shown in
fig 2. ensuring that the top 20mm of thread remains free of resin or sealant.
Page 3
20mm
Minimum
GRP
Fig 2
Fig 1

Page 4
Before pushing the sensor into the skin fitting, ensure the lower O-ring is liberally
lubricated with silicone grease. Push the sensor into the skin fitting with the arrow
pointing forward and hand tighten the securing ring.
INSTALLING THE INTERFACE BOX.
The interface box is not waterproof and should be mounted in a permanently dry
location. The box can be secured using the two mounting flanges. Carefully connect
the five wires of the sensor cable to appropriate terminals on the interface box as
shown in fig 3. Plug in the power cable and connect it to a 12-volt DC power source.
The red wire is positive and the wire with the black stripe is negative. The power cable
is fitted with a 1-amp fuse. The NMEA output can now be used to drive any compatible
speed log display.
CONNECTING TO AN NMEA DEVICE
Connect the interface box BLUE/NMEA to the NMEA input of the device. Connect the
interface box SILVER/NEG to the NMEA- or NMEA reference of the device. The NMEA
0183 output sentences are VHW and VLW.
TO SENSOR
Fig 3
TO SENSOR
IMPORTANT
DO NOT REDUCE OR INCREASE
THE TRANSDUCER CABLE LENGTH.

Page 5
x x x
SILVER / NEG
RED / +
BLUE / NMEA
BLUE
RED
BLACK
Fig 4
EM LOG
BLUE
BLUE
RED
BLACK
SILVER
x x x
EM LOG
3 WAY CABLE
RED
x x x
SILVER / NEG
RED / +
BLUE / NMEA
Fig 5
CONNECTING TO THE NASA Marine Clipper EM or Target EM LOG
displays.
The Clipper or Target EM log display can be connected directly to the interface box
as shown in fig 4. Alternatively, if a longer length of cable is required, a three-way
cable and terminal block is supplied and is connected as in fig 5. Further EM logs
can be connected in parallel and function as independent repeaters. Do not
attempt to extend the cable between the sensor and the interface box.

Page 6
CALIBRATING THE EML-2.
First the set damping level to zero. With the boat at rest in still water, a small (usually
less than 2Kts) steady error may occur. This can be trimmed out by pressing the ZERO
SET key. Only press this key when the water speed in truly zero. The setting can be
cancelled by, disconnecting the power and reconnecting while the ZERO SET key is
depressed.
If the speed reading requires adjustment then carefully turn the calibration control,
clockwise to increase the reading or anticlockwise to reduce the reading.
IMPORTANT: Do not attempt to adjust the speed calibration until the ZERO SET
procedure has been correctly performed.
USING THE CLIPPER EM LOG.
A brief press on the ILLUM key will roster the character in the lower left of the display
between H and L. When showing H, a long press on the key will increase the
backlighting. When showing L, a long press will reduce the lighting. Pressing SPEED
will show the boat speed in knots with a symbol at the centre, bottom of the screen.
When this symbol is a straight line the average speed is constant, an arrow to the right
shows the average is increasing while an arrow to the left shows the average is
decreasing.
Pressing trip shows the distance travelled, in nautical miles, since the unit was turned
on. Pressing TOTAL shows the cumulative distance in nautical miles. Note, for clarity,
the units of 1000nm are displayed at the top left of the display.
INSTALLING THE TARGET EM LOG DISPLAY.
Select a convenient position for the display on a panel or bulkhead. The site must be
flat and the cavity behind the panel must always remain dry. (The cable entry boss is
not sealed to allow free passage of air to and from the unit and prevents misting of the
display.)
The positions for the fixing holes can be marked on the panel using the drill template
on the inside cover of this manual. Before drilling check that there is enough space
behind the panel to route the cables and to allow access to tighten up the wing fixing
nuts.
Drill the five holes and check that the unit fits. It may be wise to connect the cables
before finally fixing the unit in position. Fit the sponge rubber O-ring seal into the groove
in the mounting face of the display unit.
Fit the display unit into the panel and tighten the four wing nuts finger tight only. It is
important that the sponge rubber seal makes good contact with the panel or water may
get behind the unit and enter the cavity behind the panel.
It is good practice to run the cables vertically downwards from the unit. Doing so
prevents any moisture that may collect on the cables from running back into the unit.

CLEANING THE SENSOR.
From time to time it may become necessary to clean the face of the sensor. The
sensor can be removed by unscrewing the retaining ring and pulling it out of the
skin fitting. If the boat is in the water be aware that there is no valve in the fitting
and a significant water flow will result. It is essential that the blanking plug should
be at hand, with its O-rings well lubricated, ready to push into the skin fitting.
The face of the sensor should be free from growths, paint, grease, antifouling
etc. An old toothbrush can be used to scrub the surface. If the electrodes show
any signs of damage they can be removed using a 2mm Allen key. Spares are
available from NASA Marine. Take care, when replacing the electrodes, not to get
water in the threads.
After cleaning the sensor, lubricate the O-rings with silicone grease (Taking care
to avoid getting grease on the electrodes.) and re-install the sensor with the
arrow pointing forward.
TECHNICAL SPECIFICATION
NMEA 0183 output sentences VLW+VHW
Supply voltage 12v
Supply current 80mA
Speed Range 0.2 - 40 knots
Transducer cable length 5.0 metres
USING THE TARGET EM LOG.
A brief press on the SPEED key will turn the backlight on or off. A brief press on
the TRIP key will display the trip distance in nautical miles since the EM Log was
turned on. For clarity the units of 100NM are displayed on the lower left corner of
the display. A brief press on the TOTAL key will display the cumulative distance in
nautical miles. Units of 1000NM are displayed in the lower left of the display.
After 20 seconds the display will revert to reading speed, a prolonged press of
the SPEED key will revert immediately to the speed reading display.
SETTING DAMPING LEVEL IN TARGET OR CLIPPER EM LOG
Provision has been made to adjust the display damping in response to different
sea states. There are 9 levels of damping numbered 0 to 8. Level 0 is ideal for
calm conditions and responds quickly to small changes in speed while level 8
averages the speed over a longer period and is therefore slower to respond.
Pressing TRIP and TOTAL together shows the current damping level together
with the symbols TC (Time Constant), press TRIP or TOTAL to increase or
decrease the damping level then press SPEED to store the value and return to
normal operation.

NOTES

IMPORTANT READ THIS BEFORE
UNPACKING INSTRUMENT
LIMITED WARRANTY
Prior to unpacking this instrument read and fully understand the installation instructions.
Only proceed with the installation if you are competent to do so. Nasa Marine Ltd. will
not accept any responsibility for injury or damage caused by, during or as a result of
the installation of this product. Any piece of equipment can fail due to a number of
causes. Do not install this equipment if it is the only source of information and its failure
could result in injury or death. Instead return the instrument to your retailer for full credit.
Remember this equipment is an aid to navigation and not a substitute for proper
seamanship. This instrument is used at your own risk, use it prudently and check its
operation from time to time against other data. Inspect the installation from time to time
and seek advice if any part thereof is not fully seaworthy.
Nasa Marine Ltd. warrants this instrument to be substantially free of defects in both
materials and workmanship for a period of one year from the date of purchase.
Nasa Marine Ltd. will at its discretion repair or replace any components which fail in
normal use within the warranty period. Such repairs or replacements will be made at
no charge to the customer for parts and labour. The customer is however responsible
for transport costs. This warranty excludes failures resulting from abuse, misuse,
accident or unauthorised modifications or repairs. In no event shall Nasa Marine Ltd.
be liable for incidental, special, indirect or consequential damages, whether resulting
from the use, misuse, the inability to correctly use the instrument or from defects in
the instrument. If any of the above terms are unacceptable to you then return the
instrument unopened and unused to your retailer for full credit.
Name
Address
Dealer Name
Address
Date of Purchase
Proof of purchase may be required for warranty claims.
Nasa Marine Ltd.
Boulton Road, Stevenage, Herts SG1 4QG England
EU Declaration of Conformity
This declaration is issued under the sole responsibility of NASA Marine Ltd. This product is in
conformity with the relevant Union harmonisation Legislation. Harmonised standards applied:
EU directive 2014/30/EU (Electromagnetic compatibility) EN60945:2002-08
The original Declaration of Conformity certificate can be requested at [email protected]
THIS PRODUCT IS INTENDED FOR USE ONLY ON NON SOLAS VESSELS