Tech Analysis: Boat controls

When it comes to controlling a Powerboat P1, it’s more than just wheel, stick and pedals. It’s a balancing act of high-speed proportions

When it comes to controlling a Powerboat P1, there are plenty of options for getting the best performance and speed out of the hull. Whether it’s steering with the rudder, using the trim tabs to get the boat on plane, adjusting the angle of the driveshafts and props for perfect power delivery or using ballast to adjust the balance of the boat, there’s a multitude of choice. No wonder it requires two people to balance the jobs.

The main control mechanism of a Powerboat P1 is the rudder, controlled by the boat pilot through the steering wheel. Located (as you’d expect) at the back of the hull, it helps the boat turn in the water. When you take a look at the boats out of the water, the size of the rudder – or rather lack of it – is surprising for such a powerful and big machine. But a bigger rudder would actually cause extra drag, hampering straightline speed. Some teams will use two rudders, others will mount the rudders on the engine mechanism so it turns as one unit. It’s all a matter of personal preference, like so many ‘black art’ areas of boat design.

The next control elements of note are the trim tabs. These are hydraulic flaps, located near the rudder at the rear of the hull. They’re invariably controlled by the throttleman with pulleys on or near the throttles for ease of use. They’re used to balance how the boat sits in the water. Getting the best speed out of a powerboat is all about balance – referred to by crews as ‘trimming the boat’. The boat should ride on its stern to limit the amount of hull running in the water, because this causes drag. But engines also need to be at the right angle to give the maximum thrust through the water.

This is where adjustable driveshafts come in. Most Powerboat P1 teams use a conventional straight-line shaft drive, rather than the more complex stern drives, which can be difficult to maintain and lose power. Some teams, though, used the more complex Arneson drive, which can alter the angle of the propeller while racing for optimum power delivery.

One thing that Powerboat P1 crews don’t have to worry about while racing is changing gear. Although SuperSport teams can use multi-speed boxes, the general preference across the field is for the Evolution class-standard ‘crash’ gearbox – effectively one gear. Picking the right ratio is all about achieving a balance between acceleration and top speed, and teams will monitor ocean conditions before making a last-minute selection for each race. Shorter gears are better for calm waters, whereas longer ones are more suited to rough conditions as they keep the revs up, preventing boats bogging down in the waves.

The final thing for crews to think about – but only in the Evolution class – is water ballast. Evolution crews can use hydraulic pumps at the rear of the boat to suck water into ballast tanks all along the hull’s length. These adjust the weight distribution of the boat and – in conjunction with the trim trabs and adjustable drives – can be used to perfectly balance the hull in the water for optimum power delivery and speed.

In the cockpit, the job doesn’t stop there. The pilot has to watch the GPS screen, on which is laid out the details of the course and the buoys, while the throttleman has to keep an eye on an array of engine temperature, fuel and oil pressure dials, as well as the tachometer, to avoid over-revving the engine as the boat leaps out of, and crashes back into, the water. The positions of the throttle and trim tab controls can vary from boat to boat, with some throttlemen preferring them in one location so that everything can be done with one hand, while others prefer one hand for each job – speed and boat attitude.

So, it may look easy (and fun!) driving a Powerboat P1 across the rough seas, but spare a thought for the myriad of decisions which are being made every second by the crews in the cockpit as they bounce and are pummelled from wave to wave. There’s a reason why these guys are the best in the world at what they do.