Delft resistance formula

[fredschmidt]

Rick

When I double click on godzilla.bat it open in a text editor, do not run. I think that is the ambient Wine. Was good if someone that run Godzilla in Linux Ubuntu give me a help.

fcfc

I read the paper. Is the same problem. When we use the formula and extrapolate for length beyond the basic hulls we can have fictitious values.

[fredschmidt]

Rick

I obtain run Mozilla. I open with Firefox and run with Wine.

Crazy.

Thanks Rick more one time. Was a great information use Michlet/Mozzila.

I will go see if is usable for my intents. Best regards.

[Guest625101138]

Fred
A good test of it is to use Michlet to produce data for one of the Delft series hulls to confirm how close it is. I would be interested in the results if you get them.

After that exercise set GODZILLA the task of finding the lowest drag hull having the same stability as the one you have used for the Michlet exercise.

Rick

[fredschmidt]

Rick

Annex the results for a hull do in Delftship. The file in.mlt is generated by Delftship.

I noted that Cp and wetted surface are different in the two programs.

Unhappy after dozen hulls Wine stop Godzilla. I will run as soon as possible in Windows.

[Guest625101138]

Originally Posted by fredschmidt

...

I noted that Cp and wetted surface are different in the two programs.

...

You need to check that the hull length you have set in Delftship is the LWL. This is what Michlet uses to determine the stations. If you have the overall length then the hull will be seen by Michlet being that length on the waterline. I expect you will get good areement if you make this change.

Rick W

[fredschmidt]

The Loa ~= Lwl, see annex drawing
Loa = 0.990 m
Lwl = 0.981 m

[idkfa]

Hi Rick,

What's the L/b the range for Michlet, thought is was only for slender hulls? And Delft does go thinner than, l/b > 5? But the relationship of Cp to Fn still holds?

[fredschmidt]

I run Michlet with Correct Lwl = 0.981 m

For Delft

Cp = 0.596
S = 0.144 m2

For Michlet

Cp = 0.615
S = 0.157 m2

[Guest625101138]

Originally Posted by idkfa

Hi Rick,

What's the L/b the range for Michlet, thought is was only for slender hulls? And Delft does go thinner than, l/b > 5? But the relationship of Cp to Fn still holds?

I have seen good agreement between Michell integrals and measured data on hulls with L/B of 4.

Rick W

[Guest625101138]

Fred
To determine the cause of the difference I would scale up to check that it is not a resolution error due to truncated data. I would also increase the number of waterlines and stations when exporting to Michlet to check that the resolution Michlet is getting is OK.

You can look through the offset table in Michlet and compare a few points with Delftship to check they agree. Confirm that the in.mlt file has the correct LWL.

Rick

[fredschmidt]

Rick

I change the Lwl value from 0,990 to 0,981 and the values remainder constants, the difference of 9 mm do not affect them.

Ok, I go check some offsets.