Re: A mistake of delftship for yatch design

[dssdaad]

cruzmayora

So according your book the Midship section should be located at the middle of LWL right??
ANSWER= ACCORDING TO BOOK “PRINCIPLE OF YATCH DESIGN” YES.

In the case that you mentioned here the middle of the LWL should be at 4 mts. not at 4.5 right???

ANSWER= NO, IF YOU CONSIDER AFT END OF SHIP IS X0.0 THEN THE MIDSHIP MUST BE AT X4.5 ACCORDING TO “P.Y.D.” BOOK.
YOU CAN SEE SOME PICTURES AT THE BEGINNING OF THIS TOPIC ABOUT THE RELATED PAGE OF THE BOOK.

so your book is giving you two different locations of the Midship section Half LWL and (0.5+LWL/2), right?
ANSWER= NO, MY BOOK IS GIVING ME ONLY ONE SOLUTION FOR YATCH HULLS. 0.5 IS JUST AN EXAMPLE. YOU CAN CONSIDER IT:

Xm: X COORDINATE OF MIDSHIP (FROM AFT END)
Xslwl: X COORDINATE OF START POINT OF LWL FROM AFT END.
LWL: W. LINE LENGTH
SO ACCORDING TO THE BOOK, THE MIDSHIP:
Xm=Xslwl+LWL/2
IN THE EXAMPLE
Xm=0.5+8/2=4.5m
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“Easy test. Make new (default) model which DS generates. Now try to get LCB %% right

DS “KNOWS” location of LCB for the model, just does not want to calculate LCB%% correctly.

Tell us how YOU got the right calculation for LCB%% in DS (what steps) for default model…. ”

THE REASON OF THE PROBLEM IS Xflw. THIS IS THE START POINT OF LWL. AND IT IS NOT CONSTANT. AFTER EACH HULL GEOMETRY CHANGE ALSO Xflw CHANGES. FOR THE CORRECT SOLUTION
ACOORDING TO BOOK, THERE ARE TWO WAY. DEFAULT DS LOCATES ITS COORDINATE SYSTEM AT STERN. EITHER DS AUTOMATICALY LOCATE ITS COORDINATE SYSTEM ON TO START POINT OF LWL OR Xm=Xslwl+LWL/2

I CANNOT MANUALLY ENTER Xslwl EVERYTIME WHEN GEO. CHANGED.