Trans RINA, Vol 154, Part A2, Intl J Maritime Eng, Apr-Jun 2012
The stockpile is at the export site, downsizing or eliminating the need for large expensive negative pressure sheds ashore and large wharf facilities;
Provides dust-free transhipment, eliminating issues close to residential areas;
Can handle rougher seas, therefore eliminates demurrage;
Shallower draught feeder vessels can be used from very small ports or unprepared beaches at scheduled times, eliminating the need dredging of sensitive areas;
jetty structure and the bond for its for the community
Upon completion of the mine life, a small harbour is
removal at end of the mine life; available
traditional owners;
Revenues from mining royalties can be secured at an earlier timeframe;
Reduces the need for road transport (and
associated greenhouse gases) by using small harbours closer to the mine site;
Provides employment and training opportunities in feeder vessel operations;
Reduces capital expenditure and sovereign risk; Operating expenditure can be reduced due to lower power and manning requirements when compared to more traditional systems;
Port charges, such as berthage, wharfage and tugs, can be reduced;
The FHT well dock arrangement eliminates stevedoring damage to feeder and transhipment vessels;
An FHT with SLV feeder vessels can handle inbound fuel and other dangerous goods (such as ammonium nitrate) and outsized heavy lifts into areas with little or no infrastructure;
A feeder vessel can be secured within the well dock bow first to push the FHT to redeploy to disaster sites, cyclone moorings or dry dock;
The FHT requires minimal manning (4-6 crew); The FHT has no propulsion engines or large superstructure and incorporates anchor ground tackle to suit the combination of the FHT and export vessel.
The FHT can use stern transverse thrusters to avoid beam sea conditions.
It is acknowledged that typical Landing Helicopter Dock (LHD) ships, such as the Canberra Class selected for the Royal Australian Navy (Semaphore, 2007), incorporate a similar stern door access for loading smaller vessels. However the FHT system is unique in the sense it is a permanently open aft wet dock which is not restricted to small craft only. The wet dock in this instance has been designed to reduce surge, sway and yaw effects and dampen roll, vessel.
pitch and heave motions of the feeder or for
A small shallow harbour eliminates the cost of a major
The primary advantage of the FHT system is that it can dramatically reduce transhipment delays caused by inclement weather, by greatly reducing relative motions between the FHT and feeder vessel.
The feeder is
significantly sheltered when inside the FHT well dock when compared to the more exposed location when a feeder is in a traditional side-by-side mooring arrangement. transhipment
For example, it is common for alongside operations to
typically be limited to
significant wave heights of up to approximately 2.5 metres which can be seen in many operations currently in the market. Preliminary investigations
indicate that
feeder vessel operations can be handled, uninterrupted, in seas of up to 5 metres for the FHT concept. The main purpose of this paper is to present some of the results from a series of physical model experiments which were conducted to investigate this specific issue.
3. LITERATURE REVIEW
To the authors’ knowledge, there are no publicly available studies that have investigated the relative motions of two vessels, of similar relative sizes as proposed in the FHT concept, where the smaller vessel is moored inside an aft well dock. There exist several published studies that have investigated the relative motions of two vessels in a side-by-side arrangement, with most studies
dealing with the application of
numerical codes to this problem, and their efforts to validate predictions by undertaking a comparison against limited scale model experimental data. For example, see Kodan (1984), Buchner et al. (2001), Fang and Chen (2001), Inoue and Ali (2003), Kim et al. (2003), Hong et al. (2004), Lewandowski and Naud (2004), Koo and Kim (2006), Huijsmans et al. (2007) and Xiang et al. (2007). It
is important to note that there are some significant
differences in the relative lengths of the two vessels compared to our current study. For example, the ratio of feeder length to mothership length ranges from approximately 48% up to 93% of the proposed SLV/FHT concept under consideration here. As might be expected, the range of vessel displacements also vary considerably which makes direct
comparison of the published
numerical and experimental data with the results from the present study a more complicated task, and possibly of limited value.
When two vessels are moored side-by-side, it is expected that the motion of both vessels will be affected by the presence of the other vessel, both through the mooring system and from hydrodynamic interaction. Thus, it is inappropriate to assume that the motions of any single vessel in a known seaway will be the same as the case when that vessel is alongside any other vessel. In addition, the manner in which the vessels are connected and moored can have a significant effect on the resultant motions. This is one of the reasons why validation of numerical predictions, usually through the conduct of physical scale model experiments, is so important in such cases. One common general
trend found from the
A-98
©2012: The Royal Institution of Naval Architects
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62