SKIPPER DL2 Navigation Speed Logs
The SKIPPER DL2 is a Dual Axis Doppler Speed Log, working on the doppler principle, providing longitudinal and transversal ship’s speed (STW and SOG) and distance relative to sea water. The SKIPPER DL2 gives accurate navigation parameters, measured as they happen, and presented in a logical, user-friendly way.
SKIPPER DL2 Display
SKIPPER DL2 Specification
| Speed Log: | DL2 |
| Number of Axis: | 2 and 3 |
| Speed range longitudinal: | +/- 50 knots |
| Speed range transversal: | +/-50 knots |
| Water track (from): | 2 meter |
| Temperature accuracy error: | <1°C |
| Power Supply: | AC : 115-230 V 50/60 Hz |
| DC : 24 V | |
| Power Consumption: | Max 30 W for complete speed log |
| Display: | 9″ touch |
| Mounting dimensions display: | 190x119x114 mm. Bracket or panel mounting |
| Accuracy (Better than): | 0.2 knots or 2% whichever is greater |
| Accuracy: | 1% available as an option |
| Weight: | 1.4 kgs for display |
| 1.5 kgs for electronic unit | |
| 10 kgs for sensor and 40 m cable | |
| Standard cable length: | None (max 100 m) for display |
| 40 m for sensor | |
| Mounting options: | Steel Tank |
| Aluminium tank | |
| 100 mm Sea Valve for single bottom | |
| 100 mm Sea Valve for double bottom | |
| DL850 540 kHz retrofit in ETNSLB | |
| Atlas Dolog 2x retrofit | |
| Sperry SRD 421/500 retrofit | |
| Speed alarms: | High and low speed limits |
| Power failure | |
| Sensor failure | |
| Outputs: | 2xLAN (IEC61162-450) |
| 4xNMEA0183 (IEC61162-1) | |
| 2xAuxiliary (pulse, limit etc) | |
| 1xRelay (Alarm etc.) | |
| Inputs: | 2xLAN (IEC61162-450) |
| 2xNMEA0183 (IEC61162-1) | |
| 1xAuxiliary (alarm, sync etc.) | |
| NMEA Outputs: | Speed: VBW and VHW |
| Distance: VLW | |
| Others: MTW (Temperature) | |
| Classification: | IMO Wheelmarked |
| CCS on request | |
| RMRS on request. | |
| MED-B | |
| IEC61023, IEC60945, IEC61162-1/2/450, IEC62288 and ready for IEC61924 |
One full system consist of :
| Display option : | |
| CU-M001-SB Touch | |
| Sensor options : |
|
| DL2SG-SA for 100 mm Sea Valve | |
| DL2ST-SA for Steel Tank | |
| DL2STA-SA for Aluminium Tank | |
| DL2SDR-SA for Atlas Dolog 2x retrofit | |
| DL2SE-SA for ETNSLB retrofit | |
| DL2SW-SA for Sperry SRD 421/500 retrofit | |
| DL2STR-SA for Steel tank retrofit with diver | |
| Electronic Unit options : |
 |
| JB70D2-SA Standard | |
| JB70D2-SA-OPT For extra options | |
| Extra options software : | |
| JB70D2-OPT-1PC – 1% accuracy | |
| JB70D2-OPT-SYNC – Sync features | |
| Bottom housings : |
 |
| SB-100-SB Sea Valve for single bottom | |
| DB-100-SB Sea Valve for double bottom | |
| ETNSTCL Steel Tank | |
| ETNALC Aluminium Tank |
Types of Speed Logs
Electromagnetic — These devices, also called EM logs, rely on a coil in an electromagnetic sensor. When the AC current energizes the coil, it creates a magnetic field surrounding the sensor. As a vessel moves through water, an electrical field running perpendicular to the magnetic field is produced. The sensor electrodes detect and deliver the resulting signal representing the ship’s speed to a preamplifier, which then converts it to a digital format for viewing. This process is inexpensive and has the advantage of not requiring any moving parts. However, water salinity and temperature can affect calibration. The water flow slows down closer to the hull due to friction, affecting measurements.
Pitometer — Also referred to as a pit log, the instrument uses the principle of differential pressure to determine an object’s speed through the water. It operates by submerging a Pitot tube with an opening at the base in water. While the tube is stationary, the pressure (known as static pressure) remains constant. When the tube starts moving past the water, it creates dynamic water pressure that varies based on the velocity. The effect of static pressure is removed to obtain an accurate measurement of the dynamic pressure for calculating the speed. To achieve this, a second tube is installed near the first with an equivalent static pressure. Movement through water does not generate any dynamic pressure in the second tube. The difference between the pure dynamic and static pressure readings indicates the speed of the moving object.
Doppler — Doppler transducers rely on the Doppler frequency shift effect for estimating the speed of a moving body. A transducer produces high-frequency sound pulses toward both ends of a vessel using two transmitter windows. The reflected pulses are detected by two receiver windows located in the transducer. The time delay between the transmitted signals confirms the receipt of echoes from undisturbed water surrounding the object. The vessel’s fore/aft speed vector is estimated by processing the signal information. A pre-amplifier then transmits this information in a digital format.
Impeller — These logs function by attaching an impeller or paddle wheel to the bottom of a hull. They are employed on small yachts and other such vessels.
GPS (Global Positioning System) — A sensor accesses the GPS satellite signals to pinpoint an object’s speed, in both longitudinal and transverse directions. GPS receivers with integrated rate gyros and an antenna unit calculate the heading velocity, attitude, and course. The heading is then compared in relation to the vessel’s magnitude and direction of motion in the water. The information delivered by the satellites is processed by the system, integrating the velocity data with the longitudinal and transverse ground speeds of the vessel. Speed vectors combined with data related to the rate-of-turn assist in differentiating between the vessel’s translational and rotational movement. These are required for estimating the transverse speeds for both bow and stern as given on the docking display.
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Source: globalspec.com
