Wah tadi ada yg posting nanyain soal propeller dll tapi mungkin
kehapus ya. Saya ingetnya pertanyaan pertama. Mungkin ini bisa
membantu. Tapi sebaiknya anda rajin surfing saja, toh jawabannya
sekarang sudah ada semua di internet. kalo mentok mungkin baru bisa
sharing sama temen2.
Salam
Budiman
Propeller walk
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Propeller walk is the term for a propeller's tendency to rotate a boat
as well as accelerating it forwards or backwards.
A right-handed propeller (which rotates clockwise when in forward
gear) will tend to push the aft of the boat to starboard. When in
reverse gear, the effect will be much greater and opposite. A
right-handed propeller will now push the aft of the boat to port.
Knowing of and understanding propeller walk is important when
maneuvering in small spaces. It can be used to one's advantage while
mooring off, or it can complicate a maneuver if the effect works
against you.
Propeller walk is a complicated effect which depends on ship geometry,
direction of travel, propeller direction, vessel speed and depth of
water. Three causes are identified for a vessel in deep water:-
* 1. Upward oblique flow at the propeller location.
* 2. Vertical wake distribution at the propeller.
* 3. Unbalanced lateral forces on the rudder (when set amidships)
arising from the propeller slipstream impinging on the rudder blade.
The first of these results from there being a measurable difference in
speed of water flowing close to the hull and that at lower depths
which has not been affected by the vessel's motion. At low speeds the
last effect is most pronounced and when going astern has even more
influence.
In shallow water the upwards flow from under the vessel becomes much
less strong and ultimately disappears. Model tests carried out show
that, at a very small underkeel clearance, screw bias caused a ship to
sheer to starboard (rather than port) when moving ahead and that there
is an intermediate depth where the sheer from bias is neither one
thing nor the other.
Finally, when moving ahead with the propeller moving astern, flow into
and around the propeller is very confused. Generally the overall
result for a single screw ship when stopping is a sheer to starboard,
but this is not always guaranteed; sometimes it may go the other way,
depending often on any yaw rate on the vessel when the propeller
starts to turn astern.
Other terms for propeller walk are propeller effect, asymmetric thrust
and asymmetric blade effect.
JALESVEVA YAYAMAHE
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