a) “bulbous
bow (bulb) used as a important part of the hull “ discuss the reasons in
support of this statement
04
b) explain
the reasons that in modern ship construction sometimes , bulbous bow is
completely eliminated or existing ones are being modified 04
c)
a) the properly designed bulbous bow
reduces wave-making resistance by producing its own wave system that is out of
phase with the bow wave from the hull, creating a canceling effect and overall
reduction in wavemaking resistance. as it can potentially reduce the hull
resistance considerably this lead to better fuel economy for the vessel that
are moving at speed thus it help in reducing co2 emission. In
addition bulbous bow gives additional buoyancy to the vessel at the forward
end. Strong bulb gives addition protection to the vessel in the event of the
damage in under water area of the forward
b) it has
been found that bulbs are not efficient at all service speeds (relate it to
Froude numbers). In very low ship speeds, bulbous bows have found to increase
the drag. Because a bulb is only effective when it makes its own wave, along
with the bow wave. But at very low Froude numbers, wave making hardly occurs.
But the bulb still being below the waterline, increases the total wetted
surface area of the ship, therefore contributing to increase in its skin
friction resistance.
Currently large ships
are being built that are moving at super slow speed slow steaming is becoming a
preferred option. It reduces consumption and emissions. Container ships and
bulkers now are so large that they need not go fast because their
attractiveness is the amount of cargo they can shift, reducing shipping costs.
So these large ships
are , timetabled to deliver their goods at, more economical rate. The bulbous
bow then becomes superfluous and can actually hamper efficiency as the ratios
no longer mean it does its job. Due to above on those ship bulbous bow is modified or
eliminated
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