Jetties :  These are the structures in the form of piled projections and they are built out from the shore to deep water and they may be constructed either for a navigable river or in the sea.

In rivers, the jetties divert the current away from the river bank and thus, the scouring action is prevented.
As the current is diverted to deep waters, the navigation is also controlled.
In the sea, the jetties are pr at places where harbour entrance is affected by littoral drift or the sea is shallow for a long distance.
Thus, they extend from the shore to the deep sea to receive the ships.
In a limiting sense, a jetty is defined as a narrow structure projecting from the shore into water with berths on one or both sides and sometimes at the end also.
 Jetties are exposed to severe wave action and their structural design is similar to that of breakwater.
However, the designed standards may be released to a certain extent due to the fact that the jetties are usually built normal to the most dangerous wave front.
The impact caused by the berthing ships will depend on the skill of the berthing officer, local condition of currents, wind, etc.
The berthing velocity depends upon the condition of approach, wind, etc. and it decreases with the increase in the size of the ships    _{Your Comment}