Re:Double bow bulb can be calculated for in DS
› DELFTship forum › Hydrostatics and stability › Double bow bulb can be calculated for in DS › Re:Double bow bulb can be calculated for in DS
For another perspective, here are some Froude number values
An Australian team used the DTMB 5414 model and arrived at
FN values of 0.2755 for 20 knots and 0.4136 for 30 knots. Their model testing of the DDG51 hull is described at:
http://www.cyberiad.net/library/pdf/tsl00a.pdf
and this is (IIRC) a model of 466 feet at the waterline and 505 feet LOA. For my DELFTship model these are the major values:
base model (no 2nd bulb/dome)
Design Length: 562′
LOA: 559.5
LWL: 524.16
Block: 0.4388
modified model (2nd bulb/dome, thin)
Design Length: 562′
LOA: 559.5
LWL: 524.17
Block: 0.4388
modified model (2nd bulb/dome, thicker)
Design Length: 562′
LOA: 559.5
LWL: 524.17
Block: 0.4391
The Froude numbers at various speeds:
Speed Base Model Thin 2nd bulb Thicker 2nd bulb
17.5 0.272 same as base same as base
20 0.310
26.5 0.411
27 0.419
30 0.466
38 0.590
38.5 0.598 [file name=11_2nd_bow_bulb_3.jpg size=66956]http://delftship.net/delftship/media/kunena/attachments/legacy/files/11_2nd_bow_bulb_3.jpg[/file]
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