| 1. |
- Burman, Magnus, 1966-, et al.
(författare)
-
Cost and Energy Assessment of a High Speed Ship
- 2008
-
Ingår i: International Journal of Small Craft Technology, RINA - Part B. - London : RINA. - 1740-0694. ; 150:1, s. 1-10
-
Tidskriftsartikel (refereegranskat)
|
|
| 2. |
- Ljungqvist, Kasper, 1984, et al.
(författare)
-
Comparison of Modern Keel Types for Sailing Yachts
- 2018
-
Ingår i: Transactions of the Royal Institution of Naval Architects Part B: InternationalJournal of Small Craft Technology. - 1740-0694. ; 159, s. 81-
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of three bulb keels is compared with that of a traditional fin keel. Hydrodynamic data from wind tunnel tests are used in a velocity prediction program (VPP) with the keels fitted to a 40’ cruising yacht. Two scenarios are investigated: keel retrofitting and new design. In retrofitting, the sail, mast and rig are unchanged, while in new design they are varied to obtain a constant heel angle (Dellenbaugh). Three keel materials are considered: cast iron, lead or a mix thereof. As expected, the bulb keels are superior to the fin keel in all but the lightest winds in the retrofit scenario. The differences between the bulb keels are small, but the keel with a bulb integrated with the fin is slightly slower than the keels with more distinct bulbs, in either L- or T-configuration. These are very close in retrofit, but the T-configuration has a slight advantage in the new design scenario.
|
|
| 3. |
- Pilate, J. P., et al.
(författare)
-
A three-dimensional inverse method for the design of sails
- 2016
-
Ingår i: Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology. - : Royal Institution of Naval Architects. - 1740-0694. ; 158, s. 73-87
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates an inverse process for the design of yacht sails. The method is described and then applied to the design of optimal sails for a specific yacht The proposed inverse method generates the three-dimensional shapes of a headsail and mainsail from prescribed loading (i.e. differential pressure) distributions, accounts for the effect of the sea surface, and also simulates the twist and shear of the incoming flow. The uncoupled iterative routine solves a sequence of analysis steps so that the sail shapes are deformed in such a way that their updated loading distributions converge to the specified target distributions. During each iteration equations derived from two-dimensional Thin Aerofoil Theory, calculate a geometry correction from the difference between the current and target loading distributions. This correction is applied to the sail geometry, and a vortex lattice method code calculates the updated three-dimensional differential pressure distributions, which are again compared to the target distributions. Usually only five iterations are required to converge to sail shapes that have the target loading distributions. The inverse method has been validated by inverting the traditional way of analysing sails, i.e. a set of sails with known geometry has been analysed and the loading distributions on the headsail and mainsail were calculated. These distributions were then used as an input for the inverse code. It was found that the difference in camber between the original sails and the calculated geometry is less than 0.01% of camber at the mid-span of the sails. The second part of the paper presents two methods for the design of optimal sails for a yacht One of the methods uses the more traditional analysis approach, while the other employs the inverse method described in this paper. The optimisation is performed for a Transpac 52 yacht in 12 knots (6.5 m/s) of true wind speed to obtain the best velocity made good. Results from both methods are presented and discussed and it is found that the results in terms of boat speed are similar although the trims differ slightly. However, the new inverse method is approximately nine times faster than the traditional analysis approach.
|
|
| 4. |
- Pilate, J. P., et al.
(författare)
-
A three-dimensional inverse sail design method
- 2010
-
Ingår i: Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology. - 1740-0694. ; 152:2, s. B107-B114
-
Tidskriftsartikel (refereegranskat)abstract
- Today sail shapes are usually designed using analysis methods i.e. based on experience the designer specifies a certain sail shape and then proceeds to determine the aerodynamic characteristics of this sail. Finding optimum sail shapes using such a method can involve a lot of trial and error. A new approach in sail design is proposed in this paper, where an inverse method is considered. The inverse method involves specifying the aerodynamic characteristics, and working backwards to obtain the corresponding sail shape to produce those characteristics. The paper investigates a single sail in an upwind condition. Because the solution of the inverse process is not unique, some variables have to be fixed. The sail shape is defined by three parameters: the planform, the camber, and the twist. In the present work, the planform is assumed to be defined by the class-rules of the yacht and is thus known. The sail designer has to specify one of the two possible trims: the twist or the camber. Then the theory, described in the paper, shows that there is a unique solution of the inverse process. Thus two cases are considered. The first involves a fixed twist and planform. There, the code generates the camber of the sail which will produce a given pressure distribution. The second case considers a fixed camber and planform. Here the code trims the sail twist to match the desired pressure distribution. Validation tests have been performed and results are presented. To validate the current approach, the pressure map was first computed from a specified shape. Then the resulting pressure distribution was employed as an input to the inverse method. The shape of the sail obtained with the inverse method is compared to the shape initially used in the analysis. The agreement is good in both inverse computations.
|
|
| 5. |
- Razola, Mikael, et al.
(författare)
-
Adressing localized assault loads in composite craft design
- 2013
-
Ingår i: Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology. - 1740-0694. ; 154:Part B2, s. B87-B93
-
Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the design of composite craft with respect to non-hydromechanic, local loads not explicitly covered in the basic design standards. The primary aim of this paper is to prompt a discussion on these localized assault loads and the associated robustness issue for composite craft. A background and review of craft robustness and resistance to these types of loads is presented to provide a basis for a more nuanced discussion on inherent differences between different material concepts. Through a literature review and interviews with designers and operators different opinions on what is regarded as robust craft and why are identified. Further, a discussion on how progress can be made with respect to designing more efficient craft out of composites, based on the outlining of a possible design approach, is presented.
|
|
| 6. |
- Rosén, Anders, et al.
(författare)
-
Model Experiment Addressing the Impact Pressure Distribution on Planing Craft in Waves
- 2004
-
Ingår i: International Journal of Small Craft Technology. - : Royal Institution of Naval Architects. - 1740-0694. ; 146
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the experiment was time-domain monitoring and analysis of the pressure distribution on planing craft inwaves. A model was instrumented with pressure transducers and towed in calm water, head and oblique regular andirregular waves. The transducers were concentrated to a fore matrix to capture the impact loads and an aft matrix tofollow the pressure in the transom area. In waves, the propagation of the pressure enabled a reconstruction of the impactpressure distribution time history from the transducer signals. The impact loads determined as the integratedreconstructed pressure were compared with inertia forces determined from accelerometer signals. Correlation was clearand verified the reconstruction method and the instrumentation in terms of transducer matrix position, size and density.Besides pressure and accelerations, rigid body motions, speed, wave height and resistance were measured. The paper describes the set-up, discusses difficulties concerning model hull rigidity, sampling frequencies and signal analysis, and shows on characteristic results. The paper concludes that detailed time-domain studies of the impact pressure distribution are accessible from the set-up and the suggested analysis methods.
|
|
| 7. |
- Tavakoli, S., et al.
(författare)
-
A theoretical method to explore the influence of free roll motion on the behavior of a high-speed planing vessel through a steady yawed motion
- 2018
-
Ingår i: Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology. - : Royal Institution of Naval Architects. - 1740-0694. ; 160, s. B67-B76
-
Tidskriftsartikel (refereegranskat)abstract
- This paper introduces a theoretically-based method to compute the behaviour of a planing hull in a steady yawed motion when it is free to roll. This method was developed by using 2D+T theory and the oblique-water entry of an asymmetric wedge. Sectional forces were determined using added mass theory. The forces and moments acting on the boat were computed by extending the sectional forces in the longitudinal direction. Trim angle and centre of gravity (CG) rise were found by solving the motion equations for the rigid body of the vessel. The results were compared against experimental data, and suggests that the current method has reasonable prediction accuracy for these parameters. Moreover, cases of free-to-roll and fixed-in-roll were determined and compared against each other, indicating that the trim angle of a boat is reduced, while CG rise increased in free roll.
|
|
| 8. |
- Werner, Sofia, et al.
(författare)
-
Wind tunnel test of an America’s cup keel - A test case for CFD validation
- 2007
-
Ingår i: Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology. - : Royal Institution of Naval Architects. - 1740-0694. ; 149:2, s. 23-33
-
Tidskriftsartikel (refereegranskat)abstract
- A wind tunnel test of a winglet keel model is presented. The test includes force measurements as well as a wake survey. Results are reported for several winglet pitch angles and two winglet positions. The measured trends as well as the absolute values of the forces and the wake fields can be used for validating CFD codes.
|
|
