Trans RINA, Vol 156, Part B2, Intl J Small Craft Tech, Jul-Dec 2014


Assuming that the fins are not required for a significant wave height of between 0 and 1m, from Figure 12 it can be estimated that these fins can be in the retracted position for 5% of the time a vessel spends at sea.


18000 16000 14000 12000


Figure 12: Wave Height Data for Tasmanian Waters [15] Table 17: Recommended Modifications


for


Surveyed Vessel


Southern Rock- Lobster Vessel A


Recommended Modifications


Replace Bilge Keels with retractable fins Steaming Speed Reduction Replace flat plate rudder with NACA section


Southern Rock- Lobster Vessel B


Southern Rock- Lobster Vessel C


Southern Rock- Lobster Vessel D


Southern Rock- Lobster Vessel E


Integrate keel cooling into bilge keels Steaming Speed Reduction Replace Propeller with accelerating duct and Kaplan Propeller


Steaming Speed Reduction Replace flat plate rudder with NACA section


Steaming Speed Reduction Replace flat plate rudder with NACA section


Replace Bilge Keels with retractable fins Steaming Speed Reduction Replace flat plate rudder with NACA section


SESSF Vessel A


Replace Bilge Keels with retractable fins Replace Keel Cooling with heat exchangers Steaming Speed Reduction


SESSF Vessel B


Replace Bilge Keels with retractable fins Replace Keel Cooling with heat exchangers Steaming Speed Reduction Addition of Bulbous Bow


SESSF Vessel C


Removal of Bilge Keels Replace Genset Keel Cooling with heat exchangers Steaming Speed Reduction Replace current Propeller with accelerating duct and Kaplan Propeller Addition of Bulbous Bow


Vessels 10000 8000 6000 4000 2000 0 Vessel A Vessel B Vessel C Vessel D Vessel E


Current Fuel Consumption Fuel Consumption After Adopting Recommendations


Figure 13: Estimated Current Fuel Consumption for Southern Rock Lobster Vessels Surveyed and Fuel Consumption after Adopting Engineering Solutions


The pipes used for keel cooling can also create large amounts of appendage drag if they are misaligned. By removing these pipes and


replacing them with a


circulating sea water system, the appendage drag of the vessel is reduced. If, for operational reasons, the cooling system cannot be replaced, the bilge keels should be modified to contain the keel cooling pipes.


Most of the vessels surveyed except for Vessel C operating in


the SESSF used either flat plate or


articulated plate rudders. These rudders while providing high lift


also have a high drag compared to NACA


section rudders [16]. Previous research [17] suggests that for a vessel travelling at 10 knots, an aerofoil rudder requires 4% less power than the equivalent flat plate rudder and when turned 10 degrees, it requires 3% less power than the equivalent flat plate rudder.


In summary, some of the vessels surveyed already used some of the recommendations discussed above. For example, vessel E uses heat exchangers to cool the installed engines and south eastern shark and scalefish vessel C has an articulated air foil style rudder. A list of recommendations is summarised in Table 17.


©2014: The Royal Institution of Naval Architects


B-67


Fuel Consumption (l/year)


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  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88