Quantifying sprint kayak training on a flowing river: Exploring the utility of novel power measures and its relationship to measures of relative boat speed

2021 ◽  
pp. 1-10
Author(s):  
Cruz Hogan ◽  
Martyn J. Binnie ◽  
Matthew Doyle ◽  
Peter Peeling
Keyword(s):  
Boat Speed

Why Yacht Rudders Break

2020 ◽  
Vol 162 (A4) ◽  
Author(s):  
K Klaka
Keyword(s):  
Steady State ◽  
Design Calculation ◽  
Allowable Stress ◽  
Structural Failure ◽  
Force Coefficient ◽  
Calculation Process ◽  
Sailing Yacht ◽  
Is Design ◽  
Boat Speed

For most sailing yachts, losing a rudder is probably the most catastrophic structural failure other than losing the keel. Rudder failure happens with distressing regularity. This paper examines the hypothesis that the underlying reason is design failure. There are many qualitative decisions to be taken in the design calculation process. Example calculations are presented which show that the maximum rudder force generated in steady state conditions is easily underestimated. For a typical spade rudder of a typical modern production sailing yacht, the normal rudder force should be calculated using a boat speed of at least 125% hull speed, and a force coefficient of at least 1.3. Care must be taken in selecting an appropriate value for the allowable stress of the material used for the stock.

HYDROPHONE STREAMER NOISE

Geophysics ◽  
1974 ◽  
Vol 39 (6) ◽  
pp. 781-793 ◽  
Author(s):  
M. Schoenberger ◽  
J. F. Mifsud
Keyword(s):  
Noise Reduction ◽  
Near Field ◽  
Random Noise ◽  
Original System ◽  
Coherent Noise ◽  
Signal Ratio ◽  
Motion Sensitivity ◽  
Noise Characteristics ◽  
Noise Ratio ◽  
Boat Speed

Experiments were performed to determine the noise characteristics of a hydrophone streamer that had incorporated a number of noise reduction features. In the original system, the channels to which the depth‐controller birds were attached were 3 to 4 times noisier than nonbird channels. Fortunately, the bird noise is near‐field and is eliminated simply by increasing bird/hydrophone separation to 9 ft. On this cable, no other discrete noise sources are evident. The boat, propulsion system, lead‐in cable, tail buoy, and ambient sea conditions (moderate seas) do not generate significant noise at towing speeds above 5 knots. The noise on individual hydrophones not near birds is mainly random with only a small coherent component traveling horizontally through the water from the direction of the boat. However, since the 145-ft hydrophone arrays of 20 detectors are much more effective in reducing random noise than coherent noise, the array output consists of approximately equal portions of each. A twofold decrease in the total noise‐to‐signal ratio would result from doubling the array length (to 290 ft) while maintaining the same hydrophone density. This would result in a four to fivefold decrease in the coherent noise‐to‐signal ratio and a 30 percent decrease in the random noise‐to‐signal ratio. Additional noise reduction would result from increasing the hydrophone density and decreasing the motion sensitivity of the hydrophones. (The streamer hydrophones are not the motion canceling type.) At a towing speed of 5.3 knots, the noise level recorded on an array (not near a bird) is equivalent to pressures of 1 μbar. In normal operations with an 8-gun sleeve exploder source, a stacked section signal‐to‐towing noise ratio of 3 was obtained at 3.0 sec. However, the towing noise increases as the cube of the boat speed, and the S/N ratio would decrease by a factor of 11 if the boat speed were doubled. Conversely, decreasing the boat speed by 18 percent would double the signal‐to‐towing noise ratio.

D-1 Evaluation of the effects of vibration on the boat speed and the comfort in rowing

2015 ◽  
Vol 2015 (0) ◽  
pp. _D-1-1_-_D-1-5_
Author(s):  
Akihiko ARIMITSU ◽  
Yosuke IGARASHI ◽  
Takeshi TOI
Keyword(s):  
Boat Speed

scholarly journals Rasio Jumlah Mikroplastik dan Plankton di Kawasan Perairan Teluk Benoa, Bali

2021 ◽  
Vol 4 (2) ◽  
pp. 8
Author(s):  
Felixita Abigael Raintung ◽  
I Gede Hendrawan ◽  
Widiastuti Widiastuti
Keyword(s):  
Food Chain ◽  
Water Area ◽  
Marine Organisms ◽  
Plastic Waste ◽  
Food Sources ◽  
Total Abundance ◽  
Small Particles ◽  
Closed Water ◽  
Main Producer ◽  
Boat Speed

Plastic waste will degrade in the water and will break down into small particles called microplastics. Microplastics have a shape similar to food sources for marine organisms such as plankton, where if these microplastics are accidentally ingested by marine organisms it will enter the food chain and end up in humans through bioaccumulation and biomagnification. Plankton are divided into two types, namely phytoplankton as the main water producer and zooplankton as the second energy level that connects major producers with consumers at a higher level of food. This research was conducted to determine the type and ratio of the amount of microplastic and plankton as a source of food for marine organisms. This research was conducted in the waters of Benoa Bay, which is a semi-closed water area and has a variety of activities and there are also two large rivers that can contribute to pollution waste in the waters of Benoa Bay, this can lead to competition between the amount of plastic and plankton as the main producer in food chain. This research was conducted from February to July 2020 and sample analysis was carried out at the Marine Science Laboratory, Faculty of Marine and Fisheries Sciences, Udayana University. Sampling is done by pulling the trawl horizontally with a distance of 500 meters and a constant boat speed of 5 km/hour. The composition of the types of microplastics found were film, fragment, foam and fiber. The highest composition of phytoplankton comes from the Bacillariophyceae class, while the highest composition of zooplankton comes from the Malacostraca class. The average total abundance of microplastics is 1.69 particles/m3, while the average total abundance of plankton is 2851 Ind/m3 and a ratio of 1:1687. This result shows that until now the abundance of plankton is still much greater than the abundance of microplastics in the waters. However, considering the high amount of plastic use from household and tourism activities, it can also increase the inclusion of plastic waste that will enter the ocean.

scholarly journals COST-EFFECTIVENESS OF SAILCLOTH SELECTION FOR DIFFERENT CLASSES, TYPES AND SPECIES OF SAILING BOATS

2017 ◽  
Vol 5 ◽  
pp. 22-29
Author(s):  
Svitlana Yeroshkina
Keyword(s):  
Salt Water ◽  
Basic Material ◽  
Modern World ◽  
Scientific Article ◽  
Scientific Analysis ◽  
Full Analysis ◽  
Selection For ◽  
Materials Used ◽  
Selection Of ◽  
Boat Speed

Results over of theoretical analysis for the selection of corresponding basic material of sail clothes fabric for a different classes, types and views of sailing boats are given in the article. Sailing boats needs the proper of yachting equipment, that goes both with the manipulation of boats and rigging (in accordance of views, classes and types of sailing boats). The material for sailing is elected by participants of competitions depending of the area of navigation, the strength of wind, the whole distances and boat’s possibilities, coming from technical criteria and parameters of the boats. Full analysis of economic efficiency is conducted and price politics of different material’s types for sails in accordance with its chemical composition is analyzed. The most effective type of factory fabric is certain for sewing of sails for racing boats. For a deep scientific analysis and practical realization of the investigated process an accent is done on the exposure of the most popular sailing sailcloth materials used only on the famous world regattas. These results are very important and needed foremost for the first-class skippers of modern world racing boats, to identify most practical and super persistent to the wind, the sun, salt water materials that use in sewing of racing sails. Necessary analyses and descriptions of scientific article concerning sewing of racing sails also will be useful to the yachtsmen that only begin the way in the world of cruise yachting and sporting yachting races. Importance of faithful direction at the choice of material for sails is done not only for the decision element of victories in races and regattas, but also for an answer on many questions, constrained concerning speed of boat, norm of coverage of sails and, in the end, with maneuverability, boat speed.

scholarly journals VPP-Driven Sail and Foil Trim Optimization for the Olympic NACRA 17 Foiling Catamaran

2021 ◽  
Vol 5 (01) ◽  
pp. 61-81
Author(s):  
Kai Graf ◽  
Oliver Freiheit ◽  
Paul Schlockermann ◽  
Jan C. Mense
Keyword(s):  
Olympic Games ◽  
Strong Impact ◽  
Large Set ◽  
Prediction Program ◽  
Velocity Prediction ◽  
Rudder Angle ◽  
Boat Speed ◽  
The Olympic Games

Abstract. The Nacra-17 catamaran is currently the only type of multihull that participates in the Olympic Games. It features semi-L-shaped daggerboards, allowing the boat to foil. For maximizing boat speed, the sailors have to cope with a large set of trimming parameters. Boat speed depends on sail trim, but additional trim parameters also have a strong impact on boat speed: the rake of the daggerboard and the rudder, the platform trim and heel angle and the rudder angle. The project described here tries to assist the sailors in finding an optimized set of trim parameters. This is done with the help of a proprietary velocity prediction program, which - besides solving for equilibrium of all forces acting on the boat - searches for the set of daggerboard and rudder rake, rudder angle, heel angle and platform trim, for which performance yields a maximum. The paper describes the method as well as some of the results.

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