Helming techniques for coming alongside Basics


The pivot point We have seen (see page 63) how all vessels reducing way reach a speed at which they effectively stop steering with their rudders. Understanding this is essential when coming alongside. Equally important is to grasp the fact that when a boat’s rudder steers her, it does so from the stern. The rudder is set one way and the stern is forced the other by the water flowing over the rudder blade. In fact, it is the aft part of the boat that is shoved away from the rudder. The forward part swivels the other way, with the boat effectively swivelling around a ‘pivot point’ in the vicinity of amidships. Propeller torque A further issue is that when a propeller is running astern at low boat speeds, it pulls the stern one way or the other because of the torque of its circulation. Most single-screw boats have propellers which revolve clockwise when viewed from the stern as they drive ahead. This is called a right-hand propeller and


it pulls the stern to port when it runs astern. A boat with a right-handed propeller therefore berths most tidily ‘port side to’, because as she takes way off by running her engine astern, she is naturally tending to swivel in towards the dock. If other forces such as tidal stream oblige her to berth starboard side to, so be it, but in the absence of extraneous factors, port side to is best. A boat with a left- handed propeller behaves the opposite way. Because of these features, a right-handed boat is best brought into a port-side to berth at an angle of around 30° (a). When her bow is virtually hitting the dock, she steers to starboard and swings the stern in towards the wall (b). The engine is put astern at the same time so that the propeller will help pull the stern in. She should lose the last of her way neatly alongside, giving her crew ample time to step ashore with their lines (c).


a


b c


72 | MANUAL OF SEAMANSHIP


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