Freeship & Delft

[sorenfdk]

Hi!

I have just started playing (or maybe "fooling" is a better word ) around with Freeship, and I like it!
But I do have one problem (so far!): When I try to calculate the resistance according to Delft, nothing happens! I'm using the design that comes up when I choose Files - New.

[SeaSpark]

From page 49 of the Freeship manual:

The calculation is restricted to run only if the
parameters of the model are in the same
range as those of the tested models.
These ranges are:
✔ Lwl/Bwl : [2.76 - 5.00]
✔ Bwl/Thull : [2.46 - 19.32]
✔ Lwl/Displ^0.333 : [4.34 – 8.50]
✔ LCB (in % of Lwl) : [-6.0 – 0.0]
✔ Cp : [0.52 – 0.60]
If there are no lines displayed in the graph to the right, then it's safe to assume that at least one of the parameters is out of range. You can switch to the results tab to check the details.

[sorenfdk]

Thanks for Your answer, but for once I have read the manual (well, most of it!), so I did check these parameters, and the "default" design is within the boundaries, so that can't be it...

[Martijn_vE]

Send the file to info@freeship.org and I'll have a look at it

[Mikey]

I had the same problem when importing my design to Freeship, quite a while back now. I remember that I managed to solve it by changing where the zero point was measured from in the originating programme and then re-export / import.

I also had to distort my beautiful slender hullform and make her fat and ugly to fit within the Delft parameters

Not for me...

[Martijn_vE]

I have removed the restriction that it does not calculate when the parameters are out of range. This will be in the next release (version 3.0). However bear in mind that this may produce erroneous results. The method is especialy sensitive when the prismatic coefficient is out of range, ad may even produce negative numbers for the viscous resistance when the Cp is too high!

[Mikey]

Thanks Martijn, good idea

CP is 0.56 so no problem, but LWL/BWL is 5.4...

[sorenfdk]

I just have to tell You all about this:
Martijn asked me to mail him the file that was giving me trouble. I did so, and received his answer (including a new file) within 15 (that's fifteen!) minutes! And it worked!