OK, here is my thought… Take a RC modeling plywood and make your canoe. Then make offset surface inside the hull. Fill with cement/water mix and add some sort of cotton in it to hold all together.

Yes, alter only those coordinates you need in a coordinate window, without dragging points on the screen. The approximate coordinate may be red by positioning the cross hair where you want to have the final location of any point.

When you trigger “HOME” ==> “SHOW CONTROL NET” command, you will see points on control curves. Drag them around and you will have total control of it.

Thank you all who read and helped me in figuring out this puzzle (at least for me).
The numbers were correct all along, here are the conclusion:

1. Layer density must be relative to the water density, either fresh or salt.
2. Model should not be symmetrically replicated, meaning only half of the model should be present on the screen
3. With small relative values there is an error in rounding off, at least with displayed precision numbers.

Here is the backup calculations:
Foam density 4.03 lb/ft³
Salt water density 63.99 lb/ft³
Relative density 4.03/63.99=0.06298

After calculations in Delftship:
Calculated panel weight 0.005T = 0.005 * 2240 = 11.2 lb
Theoretical panel weight @4.03 lb/ft³ = 2′ * 8′ * 0.1667′ * 4.03 lb/ft³= 10.74 lb
Difference 0.45 lb (4%)

Conclusion: In order to have correct layer weight calculations, the density must be entered in relative to the density of fresh/salt water. For example, if the foam sandwich density is 4.03 lb/ft³ and the salt water density is 63.99 lb/ft³ then the density number in the layer field should be 4.03/63.99=0.06298

Thank you all for the help, hopefully I am correct.

I tried to use values as suggested, I used 4.03 lb/ft³ in layers property and the answer – weight of the panel – was 0.3T It is definitely not correct. Then I used relative density of the sandwich component 4.03/63.99=0.063 AND reduced thickness of the panel to 1″ instead of 2″ Miraculously the weight of the panel now is 4.48 lb (0.002T) I consider this to be close to the original 4.03 lb/ft³ value because of whatever rounding errors. I still have not received a convincing answer what values should I use for layer density. I attached 2’x4’x2″ foam sandwich model – really just one flat surface with 4 corners with 2″ draft.

Can anyone help, please?

Attachments:

• 8x2x2foamboardwith2-FGskins_2013-06-10.fbm

Well, it has been a week or so, but I got exactly zero replies. I guess not so many people have time to go methodically through the above calculations. In this case my next iteration would be to claim that layer density calculations are not correct in Delftship. Or, I am doing something fundamentally wrong, which not that unusual… Would any one help me in sorting all this out? Thank you.

Any suggestions for my problem after being posted for a few days? Any at all? I have this update captured on screen dump.

This is more than just a glitch. I was working today with a model and noticed that when converting from metric to imperial the graphs and centers disappeared. I have a video clip to show it. Just rename and remove “.GZ”

Lucky for me I just did a plan view and selected all nodes at “0” and manually set them to “0.0000” in the coordinates box. After that the data was shown normally and with right precision.

Obviously most probable root of this glitch is in the rounding off error. Hopefully it will be corrected.
20121101_2215_Metric_Imperial_Bug.avi.GZ

Thanks, I havn’t thought about that. Now it works fine. Much appreciated. 🙂

I think the right way would be to import offsets in any CAD program as complex curves with a text file and make sure these lines do resemble the sail-body-plans. After that it is a matter of exporting X-Y-Z coordinates of the curves and importing them into Delftship program. It should work.

Thanks, how obvious! Somehow I thought that the midship location is defined automatically — back to the drawing board!

One down. OK, I found out how to run the program off the USB pen drive. I installed the program on the hard drive and then just copied program containing folder onto my USB drive. So far it worked.

I also figured out that older blocks do get imported into 5.06 version. Now if only I could have an option of using short-keys!

Thanks for the help.

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