Summary1. Animal-borne instruments provide researchers with valuable data to address important questions on wildlife ecology and conservation. However, these devices have known impacts on animal behaviour and energetics. Tags deployed on migrating animals may reduce reproductive output through increased energy demands or cause phenological mismatches of foraging and nesting events. For marine organisms, the only tagging guidelines that exist are based on lift and thrust impacts on birds -concepts that do not translate well to aquatic animals. Herein, we provide guidelines on assessing drag from animal-borne instruments and discuss the ecological impacts on marine organisms. Of particular concern is the effect of drag from instruments to the welfare of the animals and for the applicability of collected data to wild populations. 2. To help understand how drag from electronic tags affects marine animals in the wild, we used marine turtles as model aquatic organisms and conducted wind tunnel experiments to measure the fluid drag of various marine turtle body types with and without commercially available electronic tags (e.g. satellite, TDR, video cameras). We quantified the drag associated with carrying biotelemetry devices of varying frontal area and design (squared or tear drop shaped) and generated contour plots depicting percentage drag increase as a framework for evaluating tag drag by scientists and wildlife managers. Then, using concepts of fluid dynamics, we derived a universal equation estimating drag impacts from instruments across marine taxa. 3. The drag of the marine turtle casts was measured in wind speeds from 2 to 30 m s À1 (Re 3Á0 9 10 4 -1Á9 9 10 6 ), equivalent to 0Á1-1Á9 m s À1 in seawater. The drag coefficient (C D ) of the marine turtles ranged from 0Á11 to 0Á22, which is typical of other large, air-breathing, marine vertebrates (0Á08-0Á26). The C D of tags in reference to the turtle casts was 0Á91 AE 0Á18 and most tags caused minimal additional drag (<5%) to adult animals, but the same devices increased the drag for juveniles significantly (>100%). The sensitivity of aquatic animals to instrument drag is a dynamic relationship between the fluid flow patterns, or C D , and the frontal area ratio of the animal and tag. 4. In this paper, we have outlined methods for quantifying the drag costs from animal-borne instrumentation considering the instrument retention time (time to release from the animal) and the activity of the instrumented animal. With this valuable tool, researchers can quantify the drag costs from animal-borne instrumentation and choose appropriate tags for their intended study organism and question. Reducing drag will ultimately reduce the impact on the instrumented animals and lead to greater biological realism in the collected data.

For birds diving to depths where pressure has mostly reduced the buoyancy of air spaces, hydrodynamic drag is the main mechanical cost of steady swimming. Drag is strongly affected by body size and shape, so such differences among species should affect energy costs. Because flow around the body is complicated by the roughness and vibration of feathers, feathers must be considered in evaluating the effects of size and shape on drag. We investigated the effects of size, shape and feathers on the drag of avian divers ranging from wing-propelled auklets weighing 75 g to foot-propelled eiders weighing up to 2060 g. Laser scanning of body surfaces yielded digitized shapes that were averaged over several specimens per species and then used by a milling machine to cut foam models. These models were fitted with casts of the bill area, and their drag was compared with that of frozen specimens. Because of the roughness and vibration of the feathers, the drag of the frozen birds was 2–6 times that of the models. Plots of drag coefficient (C(D)) versus Reynolds number (Re) differed between the model and the frozen birds, with the pattern of difference varying with body shape. Thus, the drag of cast models or similar featherless shapes can differ both quantitatively and qualitatively from that of real birds. On the basis of a new towing method with no posts or stings that alter flow or angles of attack, the dimensionless C(D)/Re curves differed among a size gradient of five auklet species (75–100g) with similar shapes. Thus, extrapolation of C(D)/Re curves among related species must be performed with caution. At lower speeds, the C(D) at a given Re was generally higher for long-necked birds that swim with their neck extended (cormorants, grebes, some ducks) than for birds that swim with their head retracted (penguins, alcids), but this trend was reversed at high speeds. Because swimming birds actually travel at a range of instantaneous speeds during oscillatory strokes, species variations in drag at different speeds must be considered in the context of accelerational stroking.

This paper reviews some recent major changes made to the Senior Mechanical Engineering Capstone Design Program at UBC. The program now consists of a two-term senior level design sequence where student teams work on open-ended design problems sponsored by outside clients. In order to reinforce relevance and ensure that practices parallel those of industry, the Department recruited local senior engineers to serve as engineering mentors to the students and work in concert with the course instructors. Several milestones were established during the duration of the program year to reinforce good design practice beginning from an agreement on client needs and proceeding through concept generation, selection, analysis and finally ending with prototype construction and evaluation. The paper highlights the improvements made to the program as a result of these changes and presents an example of a student design project developed under the new model.

The University of British Columbia (UBC) and the British Columbia Research Incorporated (BCRI) collaborated to design a fishing vessel suitable for use on the west coast of Canada. This vessel, called the UBC Series parent hull form, was designed to have a large aft deck area and a volumetric coefficient comparable to those of modern Canadian fishing vessels. The resistance characteristics of this hull were improved without compromising on functionality and usable space. A resistance algorithm developed from the results for a systematic series of low-L/B displacement-type vessels, the UBC Series, was previously published (Calisal&McGreer, 1993). However, during the design process, the seakeeping performance of the vessel was never addressed. This paper describes the seakeeping performance of the UBC series in head seas. An algorithm, developed from the results of the model tests, can be used to calculate the seakeeping response of similar low L/B vessels. To calibrate the seakeeping measurement procedure, tank instrumentation, and data collection system, the ITTC Standard Seakeeping hull form (the S-175 hull form) was tested and the results were compared against published results for this hull form. The same techniques used for the standard hull form were then used to measure the seakeeping performance of the UBC Series. Possible application of the algorithm for non-UBC Series forms is also discussed.

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