Oil Drilling and Offshore Support Vessels
As oil drilling becomes depleted on land, more and
more of the offshore oil drilling have to be carried out in offshore deeper waters.
When oil drilling was initially carried out in
shallow waters offshore, they used self-elevating units called jack-ups or
liftboats. Basically, these were boats with 3-legged attachments which can
be towed to the location to be drilled and then the legs were extended
into the waters. The floating structure was then jacked up above the
water, using a geared rack  and pinion arrangement. When jacked
up, the structure looks very much like a 3-legged stool.
As the oil from the shallow waters became depleted,
oil drilling companies move further and further to carry out offshore
drilling. Column
Stabilized Units called semi-submersibles are utilized in deeper offshore oil
drilling. These consisted of hollow tank columns that can float on the
water, attaching themselves in place by tension legs fixed to the seabed.
Other offshore units like Floating Production
Storage and Offloading (FPSO), SPARS, Tension Leg Platform also become
common for offshore oil drilling in deep waters.
To support the offshore oil drilling activity, offshore
support vessels are chartered to assist the oil drilling rigs. They will
be at the vicinity of the oil rigs, with engines running all the while
ready to carry cargo in the form of drilling mud, cement, bentonite,
 brine and other chemicals. They are also required to carry
pipes, risers, and other spare parts for the rig.
Usually, they will be assisting in tug operations,
pulling the floating rigs and sometimes carry workers to and from the
offshore oil
drilling rigs.
Their size is normally less than 70 meters long, but
they have very powerful engines to drive their propellers. Most of these
propellers are controllable pitch propeller (cpp), meaning the pitch
angles of the propeller blades can be changed hydraulically, so that even
though the engine rotates in one direction, the direction of the thrust
can be change from ahead to astern and vice versa.
In addition, many of them are fire fighting vessels.
The engine driven pumps are powerful enough to send jets of water
including foam to any vessel or rig on fire. The support vessel itself is
protected by suitably spaced fixed water nozzles all around so that there
is a water curtain to cool the ship while it fights a fire on another
vessel.
The direction of the foam/water monitor where the
water shoots out can be controlled remotely from inside the bridge.
Usually these ships are equipped with bow and stern  thrusters so
that they can move sideways under its own power.
However, since the size of these sophisticated
vessels are relatively small, the crew will have to endure quite a lot of
sea movement during heavy weather. And the crew sleeping quarters can be
quite small.
Offshore oil drilling rigs rely a lot on these small offshore
support vessels to bring in their supplies and carry out their activities.
Whenever, there are oil drilling activities, you will invariably find
offshore support vessels.
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