Boat Handling Tips on travelling at speed.
The reason most of us have a nice powerful powerboat is so that we can travel at nice high speeds while the rest of the world is trundling along at an altogether more sedate pace.
While bombing around at highspeed might seem simple enough, there is a definite set of skills which go with it in order to get the maximum out of your boat in the safestand most comfortable manner.
One person who knows more than most about this is the RYA’s Chief Instructor for Motor Cruising and Power, Rachel Andrews. Rachel has been speeding around in all kinds of powerboats for over a decade now, so she’s in a good position to give some advice.
She explained: “Travelling at speed is great fun, but if you don’t handle your boat correctly and make sure itis trimmed right, then it can become uncomfortable or even dangerous. The complexities of advanced powerboat handling can best be learnt through the RYA Advanced Powerboat Course, but if you’re waiting for the weather to warm up, these tips from the RYA Powerboat Handbook will help.
It takes a lot of power to get on the plane. Once there it may be necessary to throttle back slightly to ease speed and conserve fuel. A displacement or semi displacement hull will never achieve the ability toplane on the top of the water so its speed will be governed by hull form and the power available.
Before accelerating ensure that the engine is either fully ‘trimmed in’ or to the neutral position depending on the craft. This helps the boat get up on to the plane.
As the throttle is pushed forward a powerboat begins to move from being a displacement boat at low speed and starts to climb on top of her bow wave and get on the plane.
As speed increases, less of the boat is touching the water. This reduces friction allowing speed to be maintained with less power.
Whenever turning at speed it is important to warn the crew so that they are not thrown out of the boat. Turning too sharply allows the prop to suck in air (ventilate) and lose grip on the water. Slowing the rateof turn or the amount of revs will allow the prop to grip again. Trim down before commencing a turn for greater grip and control during the turn.
When approaching a turn; set up the boat by trimming-in the leg, take off some speed, look around especially behind, warn your crew, then execute a wide turn keeping the boat on the plane by managing the throttle. If you turn too tightly most of the speed will be lost. Coming out of the turn apply power and trim-out.
S-turns(gradual turns to the right or left) can be made at reasonably highspeed as long as they are steady and controlled, when the conditions are suitable. Again use all round vision and communicate your intentions to your crew.
In turns some stepped hull designs can behave less predictably than ‘standard’ hulls and care should be taken to not trim in too far and to not reduce power suddenly in the turn. Consult the Owner’s Manual and dealer for detailed instructions relating to your type of craft.
Rachel explains the concept of boat trim: “At different speeds, your boat needs to be trimmed in different ways, both to get the maximum speed out of your boat and also the most comfortable ride.
“You can trim your boat in two ways; fore and aft – raising and lowering the bow, and from side to side levelling the boat if it is leaning to one side. Don’t forget that where you position people and kit in the boat will also affect the trim of the boat.”
Leg in to start to keep the prop in the water and help the boat get on the plane.
On the plane ease the leg out to achieve the best speed. Ease out too much and the prop sucks in air from the surface, making it spin faster but lose grip on the water, therefore slowing the boat. Ease the leg out bythe correct amount and the revs increase slightly without the throttle being adjusted, therefore speed increases.
If the boat starts to porpoise (the bow bounces up and down), trim the leg in to regain control, and then slowly ease out to re-trim.
Trim needs constant adjustment. If crew move around the boat or there is a change in sea conditions or speed, you need to check the trim. Fuel use makes the boat lighter – you may need to trim differently when tanks are full or half empty.
Rachel’s top tip: “Even when trim gauges are fitted, they can be unreliable. Practise in various conditions to get the best trim. When there are no gauges, use time increments to know whether the leg is up, down or centred. While in port count how long the tabs take to rise lower and centre. When trimmed correctly the revs rise slightly and the helm feels lighter without pull to either side.”
Trim tabs are either flat plates or vertical blades fitted either side of the boat and attached to the transom. They are used to trim or level the boat, both fore and aft and side to side. Trimtabs are controlled up and downwards by either a hydraulic or electricram system on the transom.
Tabs can be helpful when getting up on the plane. Tab down to lift the stern. Tabs should not be needed, but may help compensate for the crew standing at the rear or weed on the hull.
Although tabs are mainly used at speed, they can also be used tabbed down in marinas to increase grip on the water. Beware of powerful reversing when tabbed down, as this can cause damage to the tabs.
Tabs can make a huge difference to comfort and sea-keeping ability at speed. It is possible to achieve basic steering using one tab at a time.
Experimentation in different conditions will give the best compromise of comfort, fuel consumption and ride, but tab half down is a good starting point.
Rachel’s top tip: “If you have trim tabs and the ability to trim the drive leg then try to keep it simple. Use power trim for fore and aft trim and trim tabs for side to side trim.”
Hopefully these tips will translate easily when you get out on to the water, but for practical training, why not sign up for the RYA Advanced Powerboat course.
These pointers were taken from the RYAPowerboat Handbook, written by Paul Glatzel, if you would like to read more, pick up a copy by going to the RYA Website.
More information on Boat Handling.