Trans RINA, Vol 153, Part A1, Intl J Maritime Eng, Jan-Mar 2011 The flotel ship offers the following compared to a semi-submersible flotel: 4.1
A flotel ship is considerably cheaper to build and operate than a semi-submersible.
A ship has considerably lower costs in moving from one site to another, and moves much faster.
But flotel ships present also one important
disadvantage: a semi-submersible is more stable in motions than a mono-hull (ship-shaped) unit and is therefore more suitable for harsh environments. The problem of roll movement can be minimized for a ship with the installation of active anti-rolling systems, such us active tank anti-roll stabilizers. But the heave movement, the main cause of seasickness, cannot be avoided in a ship.
Apart from semi-submersibles and ships, mono-hull
barges have also been used for many years to providing extra accommodation for the offshore industries, also offering other possibilities such us heavy lifting or pipelaying. They
are An advantage is:
Cheaper than the other types: semi-submersible and flotel ships.
Disadvantages are:
Not self propelled. It needs tugs for movement. Only suitable for benign and shallow waters, as they are not normally provided with dynamic positioning (DP) systems, and should be anchored.
However recently, there has been an increasing number of projects of self-propelled barges (at low speeds) with DP systems, which means that they are becoming the preferred solution for many marine contractors.
In some cases, jack-up platforms are used as
accommodation vessels, but these are limited to shallow waters of a few metres depth.
The following sections consider the four types of flotels:
Section 4: Ships. Section 5: Mono-hull barges. Section 6: Semi-submersibles barges. Section 7: Jack-up barges.
We will see a representative example of each of the types.
Figure 9: main duties in a flotel ship. (source: Ocean Hotels Plc)
A flotel ship is normally tank tested to determine its ability to maintain position in DP mode and its suitability for personnel transfer in a variety of environments. Model tests should be used to evaluate passenger comfort (so-called MIR or Motion Illness Rating) in accordance with requirements for other passenger vessels related to vertical acceleration. In this
normally non self-propelled
mono-hull vessels and represent a low cost alternative in benign/intermediate waters.
advantages 4.
OFFSHORE FLOTEL SHIPS INTRODUCTION
As discussed, the use of ships as offshore flotels is quite recent, with M/V Edda Fjord being the first flotel ship with performance good enough to prompt several other projects since. During 2008 and 2009, the financial crisis and the decrease in oil price, have led to delays and even cancelations of some of these projects, but those still in development will begin operation in late 2010. Table 3 shows some of these projects. It can be seen that most of them are not pure accommodation vessels, but have other features, mainly related to offshore support and subsea construction. During the time where its service as a floating hotel is not required, the ship may be used for rapid transport of offshore personnel, in areas with which lack an established infrastructure,
Some of them may
to or between rigs, vessels or ports. also be used as
offshore
construction vessels (with a much lower capacity, of course) for subsea operations with the assistance of a remotely operated vehicle (ROV) or diving services. The large cargo deck would be used for
offshore equipment or used as a working deck for different
offshore operations such as
overhauling. Therefore, they are outfitted and prepared for the following duties:
Accommodation support. Hook-up, commissioning and start-up support. Maintenance support. Light construction work Crane operations.
Therefore, these ships are very versatile and are similar to any offshore construction vessel. The picture below from Ocean Hotels Plc illustrates quite clearly all of these ideas.
storing of equipment
A-46
©2011: The Royal Institution of Naval Architects
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