Trans RINA, Vol 156, Part B2, Intl J Small Craft Tech, Jul-Dec 2014
Table 10: Propeller Operating Conditions for Surveyed Rock Lobster Vessels Vessel
Propeller Speed Steaming (rpm)
A
B3 C D
433 333
Estimated
steaming Time (hrs/year)
217.4 2684 - 2992
244 22 750 482
Propeller speed setting (rpm)
200 244 177 300
Table 11: Recommended Propeller Clearances [11] (1) Minimum clearance between tip and hull 1
(2) Minimum clearance between tip and keel 608 3025-3344
Estimated Time Spent (hrs/year)
Pitch/Diameter Ratio
1.30 0.8
465 Unknown 805 1.3
Gear Box Reduction Ratio
3:1
4.5:1 4.5:1 2:1
(% of propeller diameter) 17% 4%
(3) Minimum distance from deadwood to propeller 1 at 35% of propeller diameter 27% (4) Maximum distance from propeller to rudder at 35% of propeller diameter (5) Maximum bare shaft length
Table 12: Recommended Propeller Clearances for Vessels Surveyed Vessel
Propeller Diameter (m)
A 0.9 B D
A B C D
v (kns) 7.00
8.50 8.00 8.00
E 7.60
1.35 0.71
Tip Hull Clearance (1.) (mm)
135 230 121
v FN Duration (hr) 0.30 1.43
0.36 5.00 0.38 0.08 0.38 15.00 0.34 12.00
s (nm) 10.01
42.50 0.66
120.00 91.20
36 54 28
Reco v (knots) 6.00 7.00 7.00 7.00 7.00
A B C
v (kns) 9.00
7.00 8.40
v FN 0.31
0.29 0.31
Duration (hr) s (nm) 24.00
24.00 10.00
216.00 168.00 84.00
CB (Estimated) Froude Number
0.31 0.36 0.38 0.34
Reco v (kns) 8.50 6.50 7.00
10% 4x shaft diameter
1 These clearances are closely associated with the number of blades and can be estimated by = 0.23 - (0.02 x n), and 3 = 0.33 - (0.02 x n) where n = the number of blades on the propeller.
Tip Keel
Clearance (2.) (mm)
Tip Dead Wood Clearance (3.) (mm)
294 441 232
Table 13: Current and Recommended Steaming Speeds for Rock lobster Vessels Surveyed #
Reco v FN 0.26
0.30 0.33 0.33 0.31
#: Vessel; v: speed; s: distance; t: time; Reco: Recommended
Table 14: Current and Recommended Steaming Speeds for South eastern shark and scalefish Vessels Surveyed #
Reco v FN 0.29
0.27 0.26
Table 15: Estimated Block Coefficient for surveyed southern rock lobster vessels Vessel
A B C D
0.48 0.5 0.4 0.4
217.36
2684 - 2992 22.1 482
Estimated Steaming Time (hrs/year)
Extra time (hr) 1.41 1.85 2.00
New Duration (hr) 25 26 12
Estimated Fishing Time (hrs/year)
608
3025-3344 465 805
Max Distance from propeller to rudder (4.) (mm)
90
135 71
Extra t (hr) New Duration (hr)
0.24 1.07 0.01 2.14 1.03
2 6 0
17 13
3 Including time spent participating in B.S.C.Z scallops ©2014: The Royal Institution of Naval Architects B-65
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