WHY YACHT RUDDERS BREAK

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.

EXAMPLE OF APPLICATION OF THE PONTRYAGIN’S MINIMUM PRINCIPLE “PMP EXTENSION”: ZERMELO PROBLEM (WITH CURRENT SPEED MORE THAN BOAT SPEED HYPOTHESIS)

We present an example of application covering several cases using the extension of the Pontryaguine minimum principle (PMP) in the case where we add a constraint on reaching a target variety at the final time: the Zermelo problem with current speed more than Boat speed hypothesis, where we consider a boat crossing a channel under a strong current and where we try to reach the opposite bank by minimizing the lateral offset or by minimizing the crossing time.

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

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.

Automated Rescuing Boat Tracking System Using Raspberry Pi

During floods, safety boats will be dispatched to help flood victims. The location tracking system is important to ensure the safety of the victim. Therefore, this project is conducted to track live locations and monitor flood survivors wirelessly. In tracking the victim’s location, a small and compact computer, called a Raspberry Piis installed on the boat and the recorded data has been uploaded online. This will help firefighters to monitor the location of the boat easily and help the victims navigate the boat to a safe place. A safety camera is installed to help firefighters monitor the situation as well. For system validation, various tests are conducted on-road, swimming pool and Panchor river in Muar, Johor, Malaysia. Hence, the performance on road is accurate. In fact, the recorded speed reading is similar to the speed measured by Google Maps. At the Pagoh Higher Education Hub (HPTP), Johor, Malaysia swimming pool, it is observed that, the faster the boat speed, the shorter the time required to complete a 50 meters trip. Finally, the river testing has shown that the boat speed increases when the boat moves in the same direction as the water current and slows down if the boat and river currents move in opposite directions.

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

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.

Why Yacht Rudders Break

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.

Modeling of Dynamics of Land Boat Based on the Magnus Effect

The motion of a wind powered land boat is studied. It is supposed that the land boat moves along a straight line in a steady horizontal wind flow. The axis of rotation of the Savonius rotor is vertical. The rotation of the Savonius rotors induces the Magnus force that maintains the motion of the load boat. Such vehicles can be used to perform transportation in large open areas, where there is an access to free wind. In this paper, the mathematical model of the land boat driven by the Savonius rotor is constructed. The quasi-steady approach is used to describe the aerodynamic action upon the system. Corresponding aerodynamic coefficients are approximated basing on experimental data. The angle between the wind velocity and the velocity of the boat is a varied parameter of the model. The equations of the model are presented as a dynamic system of the second order. The conditions of existence and stability of stationary modes of the dynamic system motion are obtained. It is described how the boat speed at steady motion depends upon the angle formed by the velocity of the boat and direction of the wind. In particular, it is shown that the maximum of the boat speed is achieved on the close-hauled course, that corresponds to the recommendations of the sail settings known in sea navigation.

PENGARUH MODIFIKASI BURITAN SPEED BOAT TERUBUK EXPRESS 6 TERHADAP KECEPATAN KAPAL

Speedboat Terubuk Express is a fast ship that is used as a means of sea transportation to carry passengers with a capacity of 60 people. Because it continues to experience losses, currently the Terubuk Express speedboat is modified by adding capacity and replacing the main drive engine which previously used an outboard engine with 4 x 200 horse power replaced with an internal engine that uses diesel fuel with power 1140 kilowatt. This study aims to determine the effect of stern shape changes and interaction total resistance before and after being modified on the hull to the speed of the ship.In this study several stages were carried out, namely a field survey to obtain the effect of size addition, making a model using Maxsurf 13.0 software, input data and running simulations using Hullspeed 13.01 then analyzing the results which included obstacles and speed.Based on the results of the analysis and calculations showed that the change in stern shape on the express speed boat speed caused L / B to increase by 1.2%, an increase in the comparison of the L / B value could affect the ability of the boat's motion and stability. The total resistance of the ship increased by 1.05% which at a speed of 35 knots before the change in total resistance was 33.5 kN while after the change in the total resistance became 35, 1 kN. Changes to the installed power engine can give a maximum speed of 49 knots with a total barrier of 47.5 kN. Increased speed greatly affects the engine seat and the strength of construction and the location of the longitudinal of bouyancy.