Estimating Ship Underwater Radiated Noise from Onboard Vibrations

The acoustic signature of an Orca-class training vessel (Patrol Craft Training, PCT) Moose from the Royal Canadian Navy (RCN) was measured at the RCN’s Patricia Bay acoustic range on Vancouver Island, British Columbia, Canada. The acoustic range trials included accelerometer measurements on the ship hull and in the engine room and hydrophone measurements at approximately 100 m from the ship. The trials were carried out at the ship speed range of 3 to 20 knots. The test data from all the trial runs was used to derive, evaluate and validate the method of estimating ship underwater radiated noise from onboard vibrations. In the investigation, the runs were split into two sets: a training set and a testing set. A least squares approximation, AQV (average quadratic velocity) SL (source level) correlation, was then applied to the training set data to formulate a transfer function to estimate the underwater radiated noise from onboard vibrations. The AQV is calculated from accelerometer measurements (vibration levels) and SL is obtained from the hydrophone measurements. The third octave frequency band (from 10 Hz to 10 kHz) SL estimations of the testing set runs (using the transfer function and AQV) are within 1 to 3 dB of SL from the hydrophone measurements. This study demonstrates a capability of monitoring underwater radiated noise from ships using only onboard vibration levels which may be of interest for future projects relating to the reduction of shipping noise against a threshold in acoustically sensitive environments.

“The Army Origin of the Royal Canadian Navy”: Canada’s Maritime Defences, 1855-1918

In 1954 army historian George Stanley claimed that naval initiatives from the eighteenth century to the 1870s by the French and British armies in Canada and the local land militia were the true roots of the Royal Canadian Navy. He privately admitted that he was being intentionally provocative. The present article, however, reviews subsequent scholarship and offers new research that strengthens Stanley’s findings, and shows that the Canadian army continued to promote the organization of naval forces after the 1870s. The army, moreover, lobbied for the founding of the Royal Canadian Navy in 1910, and supported the new service in its troubled early years. En 1954, l’historien de l’armée George Stanley a affirmé que les initiatives navales entreprises du 18e siècle aux années 1870 par les armées française et britannique au Canada et par la milice terrestre locale étaient les véritables racines de la Marine royale canadienne. Par contre, il a aussi admis en privé qu’il avait été délibérément provocateur. Le présent article passe en revue les études ultérieures et propose de nouvelles recherches qui viennent renforcer les conclusions de Stanley et indiquent que l’armée canadienne a continué de promouvoir l’organisation des forces navales après les années 1870. De plus, l’armée a fait pression en faveur de la fondation de la Marine royale canadienne en 1910, puis elle a appuyé le nouveau service au cours de ses premières années tumultueuses.

Comparison of Royal Canadian Navy Watchstanding Schedules

ABSTRACT Introduction Life on board a naval vessel is exceptionally demanding. Workdays for naval sailors can quite easily become 18+ hours long when watch schedules, training, and drills/evolutions are taken into account. Rotating watches and short off-watch periods can force sailors into a biphasic sleep pattern that is not sufficiently restful or a rotating pattern that is impossible to adapt to. Materials and Methods Six different watch systems were evaluated over four separate at-sea trials. Engineering and tactical/combat departments have had different watch systems in the past because of constraints related to the specific environment in which they work. Therefore, two of the watch systems were engineering-specific watch evaluations, three of the systems were specific to tactical/combat departments, and one watch system was evaluated with the entire company of the naval vessel. Results Both two-section (1-in-2) watch systems and three-section (1-in-3) watch systems were evaluated, which involve two or three shifts of sailors rotating through a full continuous 24-h day, respectively. Moving beyond three rotations of sailors is impossible on Canadian naval vessels due to bunk space and other limitations. The best watch system that we evaluated with respect to fatigue and quality of life at sea was the 1-in-3 straight 8-h shift system that was tested for the entire ships’ company. The system has a single 8-h daily watch obligation (red watch, 4:00 am-12:00 pm; white watch 12:00 pm-8:00 pm; and blue watch, 8:00 pm-4:00 am). The best 1-in-2 system was the 8-4-4-8 system in which sailors are on-watch for 8 h, off-watch for 4 h, on-watch for 4 h, and then rest for 8 h. Both of these two systems have the advantage of equitably sharing the Window of Circadian Low (from about midnight to about 8:00 am), especially when melatonin concentration in the body is usually at its peak, between 2:00 am and 6:00 am. Conclusions The goal of this work was to comprehensively evaluate both submarine and surface fleet watch systems. We were able to develop alternative watch systems that increased Royal Canadian Navy operational readiness and improved the quality of life of our sailors at sea.

ROYAL CANADIAN NAVY - FIGHTING THE INTERNAL BATTLE WITH A BATTLE DAMAGE CONTROL SYSTEM AND EMBEDDED KILL CARDS

Naval ships are designed for deployment in extreme and dangerous environments. In order to meet their external battle requirements and achieve mission success naval ships must maintain their ability to Float, Move and Fight. All actions taken to contain and prosecute damage, and repair and restore the capability to support the External Battle are recoverability actions and form what is called the Internal Battle. Through the ongoing development of a Battle Damage Control System and embedded Kill Cards the Internal Battle is better prosecuted through improved picture compilation, system monitoring plus personnel accountability.

Garner, Hugh (1913–1979)

Hugh Garner was a British-Canadian writer, journalist, and editor. His fictional writings reflect on the experiences of marginalized individuals, echoing his own early experiences of poverty and unemployment. Garner and his family moved from Batley, England, to Toronto, Ontario, when he was six years old, and settled in the working-class neighbourhood of Cabbagetown. The Great Depression forced Garner to leave high school in search of work to support himself and his family. He held a wide variety of jobs, working as a bicycle messenger, a factory labourer, a newspaper copy boy, and even riding freight trains across North America to pursue short-term and seasonal farm jobs. Politicized by these experiences, Garner volunteered in the Spanish Civil War, serving with the Abraham Lincoln Battalion of the communist International Brigades. After the Fascist victory in 1939, he enlisted with first the Royal Canadian Artillery and then the Royal Canadian Navy in World War II. With the war’s conclusion he returned to Toronto where he made a career of his writing, managing to support his wife, Alice Gallant, and their two children, Barbara and Hugh Jr, through the publication of short stories, novels, plays, radio and television scripts, and articles, and through his editorial work at Saturday Night Magazine and New Liberty Magazine.

Terahertz Spectroscopy and Brewster Angle Reflection Imaging of Acoustic Tiles

A Brewster angle reflection imaging apparatus is demonstrated which is capable of detecting hidden water-filled voids in a rubber tile sample. This imaging application simulates a real-world hull inspection problem for Royal Canadian Navy Victoria-class submarines. The tile samples represent a challenging imaging application due to their large refractive index and absorption coefficient. With a rubber transmission window at approximately 80 GHz, terahertz (THz) sensing methods have shown promise for probing these structures in the laboratory. Operating at Brewster’s angle allows for the typically strong front surface reflection to be minimized while also conveniently making the method insensitive to air-filled voids. Using a broadband THz time-domain waveform imaging system (THz-TDS), we demonstrate satisfactory imaging and detection of water-filled voids without complicated signal processing. Optical properties of the tile samples at low THz frequencies are also reported.