Sea Chest Research Articles

Adventures of a sea squirt sleuth: unraveling the identity of Didemnum vexillum, a global ascidian invader

The magnitude of the worldwide invasions of Didemnum vexillum Kott, 2002 has taken a number of years to be comprehended. During the past 15 years, it has been identified as different species depending on its location—D. carnulentum on the U.S. west coast, D. lutarium or D. vestum in New England, D. lahillei or D. helgolandicum in France and the Netherlands, D. vexillum in New Zealand, D. pardum or D. moseleyi in Japan. A number of recent publications refer to it as Didemnum sp. or Didemnum sp. A. This paper presents a chronology of the steps in the development of our awareness and understanding of this species based on comparative morphology and genetics, and lists invaded regions and the approximate minimum length of time it has been known in each area. Evidence is presented that D. vexillum may have originated in Japan. The importation of vast quantities of Japanese oysters and spat into many countries prior to the 1960s is discussed but eliminated as a likely vector because there are no reports of a sudden didemnid ascidian appearance prior to the 1970s. Introductions (including to the type locality in New Zealand) are very likely due to shipping (either via hull or sea chest fouling), with subsequent local spreading by fouled recreational craft, barges, etc., drifting and reattachment of dislodged fragments, and movements of fouled aquaculture stock and gear. Based on morphological and genetic comparisons of hundreds of world-wide samples, museum type specimens, and anecdotal information on the presence of this species in various locations over several or many decades, the valid name is concluded to be Didemnum vexillum Kott, 2002 due to the lack of any pre-existing published description. D. vestum Kott, 2004 is synonymized under D. vexillum.

Bow-thruster noise remediation in R O G E R R E V E L L E, AGOR-24

A program was initiated for Scripps Institution of Oceanography, sponsored by ONR, to silence the bow thruster in the research vessel ROGER REVELLE, AGOR-24. The ship suffered habitability problems during long-term dynamic positioning operations. A one-half-scale mockup of the ship’s bow thruster, sea chest, guard grids, and local hull surfaces was constructed for air tests. By measuring velocity distributions at the (absent) impeller location while separately drawing air through the mockup system at high velocity, it was demonstrated by calculation that the offending noise originated in unsteady cavitation of the impeller of the vertical-axis thruster. Several modifications to improve the flow were designed and evaluated in the mockup. Further, a modified impeller was designed on the basis of cavitation avoidance. The new impeller was designed-in-detail, manufactured, and installed along with several structural modifications of the thruster and sea chest, approved by the thruster manufacturer, during ship overhaul. No additional acoustic treatments were applied. Quantitative measurements of compartment levels of noise and vibration, and structural and water-borne noise were carried out to compare with premodification measurements. Results now indicate an absence of bow-thruster cavitation noise in adjacent compartments during DP operations. Thrust performance was preserved.

Leon Edel: In Memoriam

Leon Edel: In Memoriam Daniel Mark Fogel On September 5, 1997, four days short of his ninetieth birthday, Leon Edel died at his home in Honolulu, Hawaii. His Life of Henry James is not only by far the greatest work of scholarship and criticism on Henry James but also one of the finest biographies ever written, and even, as John Aldridge put the case a quarter of a century ago, “one of the truly distinguished works of scholarship . . . of all time.” The New York Times obituary of Edel (Monday, September 8) quotes more recent opinion to much the same effect: the novelist Louis Auchincloss calling the Life “the great American literary biography,” and the poet Richard Howard hailing it as one of the “grand English-language biographies of our time,” providing “the replete characterization of a fully creative human existence.” No student of Henry James will agree with Leon Edel on every point. Some of us differ with him very sharply on fundamental issues in interpretation of James’s life and work. Yet all of us are so deeply in his debt that we are barely conscious most of the time of how much our fundamental knowledge of our subject, as pervasive for the student of James as the air we breathe, has been derived from Leon Edel’s lifelong labors—from the Life of Henry James, of course, but also from Edel’s discovery and preservation of basic materials (for instance, Henry James’s letters to Morton Fullerton and to Alphonse Daudet that Edel discovered in Paris soon after entering the city on the heels of General de Gaulle in 1944) and from his James editions and scholarly resources, among others The Complete Plays of Henry James, The Complete Tales of Henry James, the four volumes of Henry James Letters, the Bibliography of Henry James (with Dan H. Laurence), The Complete Notebooks (with Lyall H. Powers), and The Library of Henry James (with Adeline R. Tintner). Born in Pittsburgh, Pennsylvania, the first son of Jewish immigrants from Russia, Simon and Fannie Malamud Edel, Joseph Leon Edel was raised in the Canadian Midwest. After earning his bachelor’s degree at the age of nineteen at McGill, Edel proposed to write a master’s thesis on James Joyce. He was rebuffed by his professor, George Latham, because “A writer has to die before we write dissertations about him.” Latham suggested to Edel, however, that Joyce and other modernist experimenters “all go back to Henry James.” “Henry James!” Leon Edel exclaimed. “Who’s he?” [End Page 207] By 1928 he had produced a master’s thesis on James and had developed his first major Jamesian theory. Discerning, in Percy Lubbock’s edition of James’s letters, the rough contours of the Guy Domville debacle, Edel hypothesized that James derived from his theatrical experience, albeit an episode of public failure and humiliation, lessons that proved invaluable for the novels and tales of his last two decades. Ten years later, as the first person to examine the contents of a sea chest of James’s literary remains packed by the novelist’s amanuensis, Theodora Bosanquet, Edel found his theory confirmed in a famous passage in the writer’s notebooks, James’s affirmation to himself that out “of all of this wasted passion and squandered time” he had learned a “precious lesson,” “the divine principle of the scenario.” Edel went to Europe in 1928 as the winner of a prestigious Province of Quebec Scholarship. The stock market crashed. He decided he should earn a higher degree, and he enrolled in doctoral study at the Sorbonne, where he wrote two James dissertations, one in English on the prefaces to the New York Edition, the other in French on James’s theatrical experiences (the basis for the monograph-length introduction to The Complete Plays of 1949). In 1929, Edel began a series of interviews with persons who had known Henry James. He interviewed G. Bernard Shaw, Theodora Bosanquet, Harley Granville-Barker, Allen Wade, and James’s valet, Burgess Noakes, among others. He met Morton Fullerton, who had been James’s friend since 1890 and who for a brief period was Edith Wharton’s lover. He befriended Wharton...

Vortex-Induced Vibration Experienced on Sea Chest

A rare kind of structural vibration induced by flow was experienced on sea chests of high speed ships. Model experiments in cavitation tunnel revealed the cause of vibration and the mechanism of excitation. The results showed that the free shear layers flowed into the cavity of sea chest were rolled up periodically into vortices and the vortex excitation resonated with the natural frequency of the vibration system composed of the sea chest structure and the water involved in it. Countermeasures reducing the excitation were also obtained by the model test.Energy method was applied for the estimation of the natural frequency of sea chest vibration system. The calculated results by this method were verified to correlate well with the results of vibration test on sea chest model, together with the measured results on actual ship.

シーチェスト防食亜鉛装備基準

Machinery Plant Committee Group III reviewed and partly altered the original standard established in 1971.The standard gives standard design, calculation method such as current density and service life, and fitting method of sea chest protective zinc.

Temporal and spatial resolution of pump sampling systems

A simple empirical method is described for determining the fine-scale resolution of continuous flow-through sampling systems. An input delta function is provided by injection of fluorescent dye into the sampler intake. The output fluorescent signal provides time-domain estimates of delay and signal spread; Fourier transformation of the output provides the frequency domain transfer function of the system. Systems with direct intakes (hose or through-hull fitting) can resolve features of 30-s duration or less; however, sea chest intakes cause substantial blurring of the input signal. Attempts to increase vertical spatial resolution by slow lowering rates can result in profiles characterized by appearent micropatchiness and multiple layering, artifacts of the procedure.