The Ship Transverse Thrust are includes the following points: On last article we have already share about Speed Control of a Vessel. Make sure you also already read it.
* Ahead movement of the propeller: The effect of transverse thrust when making an ahead movement is less worrying than that of an astern movement. Perhaps because the result is less noticeable. The net result is a tendency for a right-handed propeller to give a small swing to port when running ahead.
* Astern movement of the propeller: The helical discharge, or flow from a right handed propeller would strike the starboard quarter of the hull and create a substantial force to swing the stern to port, giving the classic ‘kick around’ or cant of the bow to starboard.
* Pivot point and transverse thrust: When a vessel is making a slow headway, the pivot point lays forward of amidships and thus the turning lever creates a substantial turning movement. So you must consider that at higher forward speed the astern transverse thrust would not hit the quarter. However at progressive slower speed, the astern transverse thrust becomes more pronounce and reaches its peak just prior to the ship being completely stopped.
With the same ship is making sternway, the pivot point moves aft of amidship. This time the turning lever is much shorter and results in a smaller turning moment. This force may be poor in comparison with stronger wind or tide forces acting at the forward of the pivot point.
In certain pilotage situation, it can be apparent when at colose proximity with solid piers, the astern trunsverse thrust can be used to advantage by reacting in the opposite direction i.e. for a right-handed propeller, the bow cants to port. This technique is known as the “Wedge Effect“. Similary, in the vicinity of shallow water, the same effect can cause the transverse thrust to reverse. In the case of a right-handed propeller, the upward water flow on the port quarter is restricted by the small Underkeel Clearance (UK) and would cause the bow to cant to port.
With a left-handed propeller, it is simply a case of remembering that the results a transverse thrust are opposite. In case Controllable Pitch Propeller (CPP), the direction of rotation is constant no matter what movement is demanded.
Thats a few about Basic Of Ship Handling Principle, for the others, later I’ll write on a different topic. Hopefully, by knowing the Basics of Handling Principle, we can maneuvering a vessel with well. Later maybe we will share a litle about Pilotage Guidanes for Ship Master If you have any Questions, suggestions, or different opinions, you may contact by comment box here. Let’s share for Berita Kapal reader !