Advanced Aerodynamics and Hydrodynamics for Powerboats

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.]