Friday, July 3, 2009

Online Computer Simulator Uses Input Data to Predict Your Boat's Actual Performance

We recently came across - which describes itself as "an interactive performance prediction program that actually simulates the conditions present under your boat," and provides you a full report on it's potential performance. Among the things the simulator is designed to show are the required RPM and power for all speeds, shown in dyno-sheet format; the projected top speed and RPM; and the rate of propeller slippage.

The idea has a lot of potential and could be very useful for things like checking to see if your current setup is optimized, planning a future repower or engine upgrade project, or even for choosing a prop to run on your favorite high-altitude lake. In theory, accurate predictions of performance could allow you to save money on power upgrades by helping you purchase the right parts, and reducing trial-and-error.


In depth, here are some of the parameters that the simulator takes into account:

-Hull dimensions, weight and aerodynamic characteristics
-Special hull features: Steps, Running Strakes, Keel Pads
-Engine Dyno Data: (two options)
-Input actual dyno sheet data
-Use a generic dyno curve based on your engines' power
-Power to 3000 HP
-Amazingly accurate modeling of hydrodynamic, viscous and aerodynamic lift and drag.
-Drive Units
-Uses a library of hydrodynamic data to support 17 different production & racing drive units!
-Gear ratios for all popular drive units compiled in one place!
-Adustable propshaft height and setback
-Your choice of propeller type, pitch, diameter, blade-count, and finish
You specify the conditions:
-Ambient temperature
-Altitude correction
-Salt, fresh or brackish water

The code was developed over a decade of research, including numerous on-water tests, model testing in an instrumented towing tank, and a lot of impressive engineering. The results of this testing is said to provide highly accurate performance predictions that are sensitive to even small changes in propellers or setup you might want to make:
"The code uses the established fundamentals of planing dynamics as it's core, but takes it a few steps better. We've incorporated the effects of special hull features, and have made some landmark improvements to the way high-speed, lightly loaded hulls are modeled mathematically. Many other secrets we've unearthed along the way about how to predict the behavior of high speed hulls, drive units and propellers play pivotal roles in the software coding."
The site usually charges a penny-per-hp to do the calculations, which is actually pretty cheap - and a lot less than buying the wrong set of cleaver props. But the site is offering a free trial version (and has been, since 2006, apparently) that allows you to run up to single or twin 375 HP Mercury Magnums - to see how it works. So it might be a good thing to check out and test. Those of you who are more technically oriented than I am would be better judges as to the program's accuracy, but if it's relatively reliable, it might be a useful tool for a lot of performance boaters. If you do, let us know what you think about the results!

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