Bat Blaster - How it works

The Principles of Audio Slalom

The Bat Blaster is intended for use in Audio Slalom - an event similar to regular slalom water skiing, but with the crucial difference that there are no physical buoys.

Instead of the skier rounding 6 symmetrically placed buoys in a fixed length course (as in regular water ski slalom) the skier must generate six audible signals from a device known as an Audio Slalom Signal generator (ASSG) in a fixed length course to achieve a clean pass and so be entitled to increase the boat speed and return for a subsequent pass.

The ASSG generates a signal when the skier is a defined distance from the centreline of the boat path - analogous to rounding the physical buoys, which are always 11.5m from the centreline of the boat path.

Bat Blaster Operation

The Bat Blaster is an ASSG, and is in fact the only ASSG that has so far been used at World, European, US, and Australian Championships. It operates by constantly measuring the angle of the tow rope and hence (based on the tow rope length) computing the skier's position every 10 milliseconds.

The unit also determines when a skier commences a pass by monitoring for the first time the skier crosses the boat wake from left to right. At the start of the pass, the unit begins a timed period (course length divided by boat speed), and in this period generates one loud signal each time the skier reaches the appropriate width - for audio slalom, the course width is currently defined as 9.1m.  The unit counts these imaginary buoys scored by the skier, and indicates the end of the pass with two short blasts for success (six imaginary buoys) or one long blast for fail (less than six buoys).

Physical Construction

The main elements of the Bat Blaster are

• a hinged aluminium clamp that locks on to the trick release fixing area on the tow pylon
• a tracking arm which attaches to the tow rope and activates a rotary sensor embedded in the fixing clamp
• a very loud horn mounted above the fixing clamp
• a control unit with LCD and six operator buttons mounted on the fixing clamp, facing towards the boat crew for simple operation.

Most elements of the Bat Blaster are fabricated in aluminium. The control unit is die cast and sealed to IP66 specification (i.e. it is rain proof and dust resistant, but would probably not survive being dropped in a lake).

Power Supply

The Bat Blaster has a rechargeable internal NiCad battery giving power for approximately 50 passes of the course. Chargers are available for recharging from European/Australasian mains (220-240V) and US mains (115V). A universal socket adapter is available for the 240V charger to fit most European and Australasian wall socket pin configurations.

Power leads are also available for powering the Bat Blaster directly from the electrical power supply in the tow boat. These leads provide power to operate the unit even if the internal battery is completely drained. They will also simultaneously recharge the internal battery provided the boat engine is running. Leads for powering the unit from the boat battery are available either with a cigarette lighter socket plug, or with alligator clips for direct battery attachment. If your boat battery is easily accessible, the alligator clip leads are recommended for most trouble free operation if the internal battery is completely drained (the cigarette lighter socket does not always provide an entirely solid connection).