Marine - Shipboard Underwater Log / Speed Log Equipment

Description:

The Underwater Log Equipment measures and indicates the speed of the vessel and its distance traveled through the water. It also transmits this data electrically to the various shipboard navigation, sonar, fire control and weapons systems as required.

Types of Underwater Logs:

Electromagnetic Log

The Electromagnetic Log operates on the principle of an electromagnetic field and electromagnetic induction.

Major components:

Sea Value - Mounted in the hull of the ship, the sea value and packing assembly provides a watertight support for the Rodmeter. It also functions to seal the hull of the ship when the rodmeter is removed for maintenance.

Rodmeter - The rodmeter provides an AC signal that is proportional to the ship’s speed. The rodmeter or “SWORD” as it is sometimes called is easy to identify. It looks like a long sword hence its name. The sensing unit of the rodmeter is contained in the “BOOT” at its lower end. An electromagnetic field is used to detect changes in the ship’s speed by electromagnetic induction.

Indicator – Transmitter (I/T) - The Indicator – Transmitter displays the ship’s speed on a dial and the distance traveled on a counter. The primary internal components of the I/T are the speed servo, the integrator and the distance servo. The I/T has output synchros that transmit ship’s speed and distance information to ship’s systems throughout the ship.

Electromagnetic Voltage Simulator (ELVS) - The Electromagnetic Voltage Simulator (UL-1000) is a piece of test equipment designed to simulate the voltage produced by the rodmeter to test and troubleshoot the ship’s speed log indicator – Transmitter independent of the Rodmeter. The ELVS is supplied with a variety of connector – cables so that it may be used with the majority of I/T types.

Model Examples:
Litton Log Equipment
Control Instrument Log Equipment
Gould – Chesapeake instrument
Mk4 mod 1&2
McKiernan – Terry
Mk5 mod 1
Dewey
Mk 6 mod 0,1&2
UL-1000

Original Equipment Manufacturers (OEMs):
Litton
Control Instrument
Gould – Chesapeake
McKiernan – Terry
Dewey

Doppler Log

The Doppler Log operates on the principle of transmitting pulsed sonic energy into the water and detecting the Doppler shift of the reflected signals. The Doppler shift is the difference in frequency between the transmitted and reflected signals.

Major Components:

Transducer – The transducer assembly transmits sonic energy into the water and receives back the Doppler shifted echoes.

Electronics Unit – The electronics unit houses the majority portion of the electronics for the system speed and distance processing.

Master Display Unit – The master display unit indicates vessel speed and distance traveled and contains switching that controls all system power and operations.

Model Examples:
Sperry Marine SRD Doppler Log
Raytheon Marine DSN Doppler Log
Ametek MRQ Doppler Log

Original Equipment Manufacturers (OEMs)
Sperry Marine Systems
Raytheon Marine Company
Ametek, Straza Division