Tech Analysis: GPS

We take a look at the advanced global positioning satellite technology that helps Powerboat P1 crews know where they’re going

It’s good to know your place in the world. But it’s especially important when you’re being bounced and battered at 100mph, squinting through the spray to pinpoint the next marker buoy while surrounded by other boats – some just metres away – all chasing an advantage. At such times, precise knowledge of where you are and where you’re headed is vital.

That’s when a good GPS chart-plotter can be invaluable. It shows instantly where you are, where the next buoy is, and how to get from one to the other. It also shows speed, but in the white heat of a race, that’s almost incidental. Just one measurement of speed really counts: the number of boats behind you.

Craig Wilson, throttleman of the double Evolutio title-winning #99 Fountain Worldwide 1st4boats.com team, knows more than most about that. He says GPS plays a part in keeping the speed up, especially around the marks. “It’s all about making the line around the buoy as smooth as possible, so you don’t sacrifice momentum,” he explains. “We enter wide and come right past the turn buoy at the apex, then drift wide on the exit. On the GPS, we lay out the course and in testing try to pick out the best line. We’ll spend hours figuring out the best lines.”

So GPS is a useful tool for success in Powerboat P1, but how exactly does it work? GPS – it stands for Global Positioning System – relies on five terrestrial monitoring stations and 24 man-made sattelites that orbit 12,600 miles (20,200km) above us. These plough six set furrows, orbiting the earth once every 12 hours, so at least four satellites are always ‘visible’ to your GPS receiver wherever on earth you are.

Each satellite emits a continuous signal that travels at the speed of light to your GPS receiver. By noting how long the signals take to arrive from four different satellites, the receiver can calculate the GPS receiver’s longitude, latitude and altitude. Powerboat P1 racers require just three signals, though. That’s because they’re at sea level – much of the time, anyway…

It’s an effective method. The Raymarine GPS receivers used by Powerboat P1 teams, for instance, are accurate to within three metres. These are off-the-shelf units, too, so anyone can have this level of accuracy.

Raymarine is an official Technical Supplier of the Powerboat P1 championship. The company also sponsors the #77 Lucas Oil Evolution-class team, whose pilot – Shelley Jory – originally started out in powerboating as a navigator. Familiarity with your GPS unit is vital, she says. “In a race, it’s so fast and furious that you don’t have time to think: ‘Oh, which button is it?’ You’ve got to know. It has got to be idiot proof.

“I also plot the course on a chart as backup. I then make a very simple drawing of it, which I take into the boat,” Jory says. “But you really go on the GPS. Everything is programmed into that. We have two GPS units in our boat – one is for a backup because you’re putting them under extreme pressure. But it’s amazing how strong they are. They withstand so much banging around.”

The #77 Lucas Oil boat is fitted with Raymarine C80 GPS chart-plotters, mainly because this unit offers the optimum balance of weight and size in an environment where both are at a premium. The C80 has a high-resolution 8.4-inch colour screen that remains visible in direct sunlight. It’s waterproof, and it’s easy to use. Such units can face considerable forces – spikes of up to 30g alongside continuous severe vibration and shocks.

A Raymarine spokesperson says: “Our comprehensive and punishing test programme ensures our equipment would, in fact, cope with demands well in excess of this. The human body would give up under these conditions long before the equipment did.”

The Raymarine C80 is an example of how far GPS units have come in the past decade. A GPS used to show just longitude and latitude, which would then have to be transferred to a paper chart. The C80, by contrast, is also a chart-plotter, fish-finder and radar, with inputs for SIRIUS satellite radio and marine weather. It can also talk with a boat’s instruments and autopilot.

Even with such sophisticated technology available, there’s still room for a traditional approach. #47 Silverline Buzzi Bullet SuperSport team owner and throttleman Drew Langdon, for instance, relies more on compass course and charts, an approach shaped by his experience in endurance racing events such as the Round Britain.

“We run mostly without GPS and have two compasses and two charts,” he says. “Powerboat P1 circuits are virtually line of sight. We find that a very reliable way of getting from A to B.”

In the open cockpit of a Supersport boat, such as Langdon’s, there are different stresses on a GPS unit, and the attrition rate can be higher than in Evolution. Even so, GPS does have a role for Langdon. “It can be useful for getting the first mark off the start line because the start line is the only place where you don’t know where you’re going to be,” he says.
 
Like Jory, Langdon says simplicity is everything in a racing environment: “You want simple menus. Definitely not touch-screen – impossible when you’re bouncing around. You need buttons. And handles alongside the unit so you’ve got something to hold on to when you extend your finger, otherwise you won’t hit the button you’re aiming for.”

So there you have it. GPS is accurate to within three metres, even when travelling at over 100mph on choppy seas, and your finger has to be accurate to within three centimetres on the receiver’s buttons. But then precision has always been an integral part of Powerboat P1.