Race speed measurement

[CornelP]

Guys, one question for the racers: how do you measure speed at the saw events?
Is it based on a race type transponder/antenna, GPS or radar gun? I am trying to get organized for next year, when we want to have a more official SAW race, not just the usual drag racing.
I did look at the NAMBA rule book, but could not find anything specific about how these races are organized...

[Darin Jordan]

Guys, one question for the racers: how do you measure speed at the saw events?
Is it based on a race type transponder/antenna, GPS or radar gun? I am trying to get organized for next year, when we want to have a more official SAW race, not just the usual drag racing.
I did look at the NAMBA rule book, but could not find anything specific about how these races are organized...

There are timing lights setup, I believe at 1/16th of a mile distance. Time elapsed to pass across that given distance is used to calculate the speed. A pass is done in both directions, and the average is your official Speed... It's all based on the time to travel a given distance.

[Fluid]

Two electronically controlled infrered sensors are placed 330 feet apart, and the time is recorded. Two back-to-back runs are averaged, then the time is divided into 225 to obtain the mph. This is what the NAMBA Rule Book has to say:

2. 1/16th Mile Straight-line

a. A 1/16th mile straight-line speed will be for a measured distance of 1/16th
mile (330 feet) and will consist of an average of two consecutive passes
through the course. These two passes must be made on a continuous run, with
no physical intervention by the operator or any other persons between such
passes. It is thus required that the craft execute at least a 180 degree turn
between passes.

b. Timing Equipment Specifications

i) The device or devices used to time and record 1/16th mile
straightaway record runs will be automatic infrared equipment, and
will be capable of timing to the nearest 1/l00th second

ii) The equipment used to trigger the timing equipment must have the
differences between the trigger points, when tracking from opposite
directions, of no more than four feet when checked at a distance of
300 feet. In addition, the measured difference for each piece of
tracking equipment will be within plus or minus six inches of each
other. Example: at 100 MPH, the boat will cover 1.47 feet in 0.01
seconds, thus the plus or minus six inches will still give accurate
results even at this speed.



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[CornelP]

Thank you a lot guys... now it's time to look for suppliers of systems or maybe some infrared laser sensors connected to a PLC... just have to find some powerful enough: the lake we race on is about 110m wide and quite deep, so no chance to have some gates closer together. It has to be either long range or maybe with some proximity sensors (min 20m range) on the bank.
It could actually be a challenging project!

[NativePaul]

beaten to it.