ENGINES AND PROPULSION 2 STEERING


How a boat is steered depends on the way it’s propelled. Those with outboards or stern drives steer with their drive units, while more traditional craft – that’s to say those with fixed shafts and props – must rely on rudders. Although the distinctions between them might at first seem unimportant, it makes a significant difference to their handling techniques – a subject we shall be dealing with later in this chapter.


Steering with prop thrust Basically, if the thrust is dead astern, the boat will move forward in a straight line. If the thrust is directed, say, towards the starboard side, the stern will be pushed to port and the boat will swing to starboard. Naturally, the opposite would be true if you turned the helm the other way. An important point to remember is that the ability to steer is entirely dependent on the thrust. As soon as you put the engine in neutral you lose that control. Both outboard motors and stern drives share this characteristic and, since outboards are likely to be the commoner of the two on angling boats, from henceforth we shall lump them both together under the word ‘outboard’.


Steering with a rudder


The usual arrangement is to have the prop immediately forward of the rudder so that turning the blade can deflect the prop’s thrust – also called prop-wash – from side to side. In some ways this achieves the same result as the previous method but there’s one crucial difference. Although the prop-wash makes the actions of the rudder more powerful, it isn’t absolutely essential. So long as the boat continues to move


through the water there will be waterflow over the rudder blade and you will have some steerage, regardless of whether the prop is turning or not. Unfortunately, some motorboat rudders can be very small – particularly those on high speed planing craft. Without the prop- wash these are virtually useless. However, most angling boats are designed to operate at low speeds, so have sensibly sized rudders – something this book takes for granted in all the situations described.


Rudder steered boats don’t steer particularly well astern. This is because the prop-wash is no longer flowing over the surface of the rudder, which must then rely on whatever waterflow there is.


RYA Seamanship for Sea Anglers 17


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