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TBDP©/VBDP© 'Maximum Velocity' (Velocity Analysis)'
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BREAKTHROUGH! 
'Velocity Optimization Analysis' by AR's unique analysis and TBDP©/VBDP© software.


Performance analysis of a hull design is best evaluated throughout the full operating velocity range of the hull/setup.  Testing performance characteristics at a specific velocity can be helpful, but performance and dynamic stability at one velocity is not always representative of conditions at other velocities.  It is important thus, to establish a maximum limiting velocity of the hull/setup, as an upper bound of full-range velocity analysis. This process is also valuable to help know 'how fast can my boat go?'

TBDP©/VBDP© software's 'Optimize=Velocity' analysis can complete performance checks to find required Trim Angle (WAngle), using maximum Power Available, to satisfy loading solutions at any velocity.  With 'Auto WAngle' feature, an analysis can be completed through the full operating velocity range to ultimately establish a 'Maximum Limiting Velocity' - there is no other Power/Trim Angle solutions beyond this MLVelocity. All hull performance characteristics can be calculated throughout this full velocity range to show operating and dynamic stability responses. 

Maximum Limiting Velocity - The above analysis procedure importantly establishes the potential maximum velocity that the hull could achieve based on available Power and unlimited Trim Settings. This establishes a velocity bounding, but disregards stability influences that could further limit real attainable velocity. Further analysis (using: Angle Optimization or Power Optimization or Economy Optimization) is necessary to examine the performance results to consider Dynamic Stability characteristics and safe operating settings, and so to determine Practical Achievable Velocity. For example, there are often (usually) stability issues that occur at a velocity less than MLVelocity that can prevent the boat from getting to the theoretical maximum. It's important to recognize these differences.onset of instability is the change in rate of required full power "WAngle" (trim angle) through the velocity range. If the required "WAngle" increases to very high values or the 'rate-of-change' of WAngle shows dramatic change (+ or -), then the upper velocity limit of the hull design and setup may be related.  If this maximum velocity and rate of required WAngleto reach Vmax is acceptable to you then ok - otherwise you may want to modify design, setup or operating characteristics accordingly.

Maximum Practical Velocity - When a key performance characteristic, such as trim angle, or dynamic stability change) shows a significant change this may indicate that the hull/setup is in the region of 'Maximum Practical Velocity'. TBDP/VBDP software analyzes derivative (rate at which a function is changing at a given point) of key performance indicators (eg: δxCFDynamic/δV, δTrimAngle/δV, δPorpoise/δV) to calculate key velocity of inflection to predict critical operating velocities.

This is often seen as a significant change in required 'Trim Angle (WAngle)', 'Dynamic Stability' or 'Hump/Transition Zone' or other key indicators. Operating velocities greater than this MPVelocity value may be approaching a region of unstable or unsafe operation for this hull/setup. TBDP©/VBDP© software can generate a series of analyses to establish the velocity that is evaluated as 'maximum Practical Velocity'. This is a unique analysis (using Angle Optimization or Power Optimization or Economy Optimization) of trends and significant changes of key performance results that can indicate that the hull/setup is in the region of 'Maximum Practical Velocity', which is less than 'Maximum Limiting Velocity' and represents more practical region of stability.

Note: All of these (above) steps can be done automatically using the 'Auto 1-2-3 Performance Analysis Wizard' to guide you through the 3 steps of Velocity, WAngle and Power Analysis.

For example, an indication of hull behaviour and onset of instability is the change in rate of required full power "WAngle" (trim angle) through the velocity range. If the required "WAngle" increases to very high values or the 'rate-of-change' of WAngle shows dramatic change (+ or -), then the upper velocity limit of the hull design and setup may be related.  If this maximum velocity and rate of required WAngleto reach Vmax is acceptable to you then ok - otherwise you may want to modify design, setup or operating characteristics accordingly.

 

Test Velocity - Alternatively, TBDP/VBDP can "Set for TEST Velocity" which will automatically set the program parameters to calculate the Velocity at a specified Trim Angle (START ANGLE).  This option is useful when evaluating the effect of small design configuration changes or dimensional changes on performance and velocity.  For example, the complete performance effect of increasing a vee-pad hull PADWIDTH from 12" to 13" can be quickly shown using this option.  

[NOTE: that the quantified effect on performance of very small changes (such as the example above) will represent predicted results under ideal operating conditions.  These ideal conditions are of course, not always representative of typical operating situations, as there are many other factors that can also impact performance like water conditions, acceleration modes, handling/cornering conditions, etc.  The absolute predicted changes in say, velocity, can effectively be used for design evaluation purposes - you will now know what the potential performance improvement or degradation could be AT THE VELOCITY TESTED.]


Performance Analysis/Optimization Options - TBDP/VBDP can employ 4 different Optimizing methods of performance analysis, each highlighting different performance scenerios  and features. Get full performance data,data points for chosen analysis method:
1) Max Velocity or Test Velocity,
2) Trim Angles with Full Power,
3) Economy analysis with Lowest Power & Lowest Trim Angle,
4) Power Required analysis for specified Trim Angles. [includes acceleration and Elapsed Time]

Each optimizing method presents comprehensive performance results measures through full operating velocity range, detailed hull performance characteristics.

[See also 'How can I estimate the Top Speed of my hull?']


All above research results included in performance analysis software by TBDP©/VBDP©


[more about AR's research     more about AR's publications    and    technical articles/papers]
 

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