March 24, 2015 at 12:20 #37665
test: box: L=10m, B=6;m T=3m mean shell thickness=0.01m
calculated by hands:
total displ. vol = 10.02×6.02×3.01 = 181.56m2
wetted surface area = 10x3x2 + 3x6x2 + 10×6 = 156m2
delftship free result:
wetted surface area = 216
I suspect that the result by delftship is not right.Attachments:
March 24, 2015 at 16:06 #37668
nobody explain this difference?
March 24, 2015 at 17:00 #37669MaartenKeymaster
The most likely explanation for this descrepancy is that you placed this box with one side on the center line (the SB side of the box), but did not remove this side plane of the box. Then, when calculations are done, the SB side is mirrored (including this extra side): now there are two planes at the center line touching, but wetted. To get correct results remove the offending surface.
To understand what happened, move the box away from the center- you’ll see the calculations are correct.
I hope this explains the confusion.
March 24, 2015 at 17:42 #37670
thank you very much.
March 30, 2015 at 12:35 #37689
about block coefficient in delftship
In this sample, why the block coefficient is more than 1.
Cb is calucated with displaced volume in delftship?
March 30, 2015 at 16:13 #37690MarvenKeymaster
CB is calculated using the displaced volume and the length and beam from the project settings. So either the displacement is calculated incorrectly (perhaps by using the wrong shell thickness or appendage coefficient) or the length and beam from the project settings are incorrect.
June 2, 2015 at 16:24 #37750Lewis ArdronParticipant
My calculations for the volume of your “test piece” agree with Delftship.
With your calculations for whetted area you are not taking into account the skin thickness you specified. Delftship adds the skin to the outside of the lines plan.
January 19, 2018 at 09:06 #39117Markku LindholmParticipant
For wetted surface You shold take accout allso the bottomplate area, 6×10 =60.
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