Dag Pike - 50 Ways to Improve Your Powerboat Driving

Driving a displacement boat at leisurely speeds leaves you all the time in the world to make decisions not that there are too many decisions to make at single digit speeds, because you will just tend to set a comfortable speed and go. That all changes when the boat is planing and you are travelling at speeds of 30 knots or more. The first thing you have to appreciate is that the time available for reacting to situations becomes compressed as the speed rises and this means that a much more intense focus is needed for driving the boat.

The speed factor affects different aspects of the driving experience. For example, when youre driving the boat at higher speeds the waves approach rapidly or even very rapidly and the reduced time factor means that both the boat and the driver have less time to recognise and adapt to the changing wave patterns.

There is less time for the driver to make the necessary driving decisions, for the speed of the engines to vary under throttle control, and for the boat to change its attitude in relation to the waves. We will look at many of these aspects later, particularly engine and propulsion response, but the reduced time needed to respond to changing conditions can mean that they are not effective at higher speeds.

Left to its own devices and at a constant speed, a displacement boat will normally find its own solution to the changing wave patterns. In a planing boat there will be times when the speed at which the boat is running will be excessive for the conditions. Here you need to respond with the controls to help the boat negotiate the waves, always assuming that there is adequate time for the necessary changes to take place.

Then there is the question of navigation. Even at modest speeds of 1.6km (1 mile) every two minutes, the navigation situation will be changing quite rapidly and you need to focus to keep on top of the situation.

Finally there is the increased stress on the boat and its crew that comes from higher speeds. Again you can help here by intelligent use of the controls, but the condensed time frame can mean that you have little time to recover from one wave impact before the next.

When speeds move above the 40-knot mark, the time factor assumes increased importance. Driving at these speeds does mean that you have to appreciate fully just how quickly things can change. The reduced time available for every decision and every response does not allow time to relax. Indeed, if you find yourself relaxing in a boat travelling at over 40 knots it could be argued that youre not doing the driving job properly. In open waters there may not be anything close by to give the impression of the reduced time scale and its only when you are operating in crowded waters that the difference becomes apparent as other craft and navigation features rush by. It can be difficult to imagine what it must be like when racing at 120 knots or more.

You dont have the luxury of time in a fast boat and it is important to recognise this at an early stage because the short time available will govern much of the way you operate the boat.

AT HIGH SPEEDS THINGS HAPPEN VERY QUICKLY AND YOU NEED TO FOCUS ON THE DRIVING AS WELL AS THE NAVIGATION.

Driving a fast boat in calm conditions is pretty straightforward. Once you get the boat up onto the plane you can largely set the throttle and let the boat go except, of course, you always need to be prepared for the unexpected, such as debris in the water or the wash of passing ships. Once waves come into the reckoning, the whole scenario changes. Not only do you need to trim the boat to match the conditions but you also need to take into account that waves are rarely regular and in any wave train you will get larger than average and smaller than average waves. The smaller than average waves are not going to be a problem but it is those larger ones that you need to focus on and build in a safety margin.

The problem with larger than average waves is that you are unlikely to recognise them until they are virtually on you. In some cases they can be transient and disappear before the boat encounters them and in the same way they can appear at short notice right in front of the boat.

Because of the varying and largely unpredictable nature of the waves you can encounter, you dont want to operate the boat right on its limits, and you need to build safety margins into your driving of the boat so that you have something in reserve should that larger than average wave suddenly appear.

We tend to focus on larger than average waves, but for every larger wave there can also be deeper than average troughs. These deeper troughs are a worrying phenomenon because you wont see and recognise them until you virtually fall into them. A larger than average wave may be sighted two or three waves ahead but that deep trough will only be recognised when you come over the crest of the wave that precedes it.

Driving a fast boat right on its limits is exciting and this is what you do when racing, but in normal cruising operations you want to keep something in reserve. The main reserve that you have to play with is the speed of the boat, so easing back on the speed immediately builds a reserve of performance. The question is how much of a reserve do you need?

A lot will depend on the prevailing sea conditions and the response time of the boat but a reduction in speed of 5 knots from the maximum or, say, 10% less than the flat-out speed for the conditions would be appropriate to give you a margin of safety against the unexpected. Like most things associated with fast boats, there are no hard and fast rules, but you will know when you are driving on the limit and when you feel that you have a comfortable margin. Taking that hard edge off the speed will also make life on board more comfortable for the boat and its crew.

IN STORMY CONDITIONS YOUR SAFETY MARGINS BECOME QUITE SMALL.

Unless the conditions are very good with a near flat calm, you will not be able to relax when driving a fast boat. Even in calm conditions you will need to be aware of the unexpected happening, such as the wash of a ship arriving in your path. In most cases when there are waves, the conditions will be constantly changing, and you will rarely find regular wave patterns where you can set the controls and let the boat take its course. On larger powerboats this can be possible, but on smaller craft up to, say, 12m (40ft) in length you will have to drive the boat with constant adjustments to the controls to optimise performance.

Two factors come into the reckoning here. First of all, it will take you time to assess the change taking place, perhaps the height and shape of a particular wave that the boat is encountering. This is called the reaction time. Then there is the time that it takes to work out your response to the situation in terms of what adjustments, if any, are necessary to the controls, and then to implement that action. This is called the response time; added to that theres also the time it will take for the engines to respond.

If you add the reaction and response times together, you have the time that it will take you to safely negotiate that particular wave. We are talking here about very short time intervals, normally fractions of a second, and when you are skilled at fast-boat driving the reaction and response times will be very small indeed. However,even an experienced driver will still be dependent on the response of the boat itself. A big heavy boat with diesel power is likely to be a slow responder, which is why it is common with such boats just to set the throttle at a comfortable speed and let the boat take its course. Any change in the throttle setting is unlikely to take place in time for it to be effective.