New Lines Prediction Program

[Remmlinger]

I have written a lines prediction program for sailing yachts. Based on the few input parameters that are required for the resistance prediction, the software creates a faired hull. The output file contains a table of offsetts, that can be read by several CAD-programs.
The program can be downloaded at

http://www.remmlinger.com/UliLines.html

Have fun
Uli

 

[quequen]

Amazing job mr. Remmlinger!. One can imagine the next step: input just LOA, Beam, Disp., an iterative genetic algorithm finds the best Cp, Cb, faires your linesplan and traces the VPP polar chart. Then we have the time to watch some Müller / Messi goals at youtube .
A similar approach, thought, was made by mr Marcus Boyle with his PolyCAD and Yachtlines. Impressive work too, although I'm not shure if resistance is taken into account.

 

[Remmlinger]

YachtLINES

Thanks a lot Quequen for the reference to YachtLINES by Marcus Bole. I did not know that software and just tried it. It is indeed very similar to my idea, but the math that he uses is different and the result is less suited for my purposes than those of my own program UliLines. I tried to create the Delft parent model Sysser 25 with YachtLINES but the result is disappointing. The sections are not close to the published lines plan of Sysser 25. But thanks again for your comment, it is always interesting to find out what competitors are doing.
As for the Müller / Messi goals I have to admit that I did not watch a lot soccer this year. We had a beautiful summer and I live close to the shore of lake Constance......
Regards
Uli

 

[Remmlinger]

Feedback ?

After about 100 downloads from my website I would be interested in some feedback. Especially I would like to know if somebody analyzed the results in Rhino, Delftship or Michlet.
Uli

 

[Mikko Brummer]

This is brilliant, thank you Uli! I have a database of 7000 sailboats, with more or less all that data in there for each boat. However, when I tried with the Dehler 33, I get this truncated stern - can you suggest what to change?

 

[Remmlinger]

Dehler 33

Thanks Mikko for testing my program!

I happen to have an input file for the Dyna-ship. This is a Dehler 33 with an increased draft (+ 60 mm), see attachment. It should run properly. The data was taken from Karsten Hochkirch's PhD thesis and also measured from an Rhino-file of the hull.

It seems that in your input file the waterplane-area is too small and in addition the LCF is rather forward. Therefore the program reduces the beam in the rear, which leads to the unrealistic stern. How did you determine the Awl?

The stem at the bow is of course not that of a Dehler 33. As I was mainly interested in the underwater part of the hull, I did not ad additional control parameters for the modeling of the stem. The best thing to do is to cut the bow off, like you did it.
Uli

 

[Mikko Brummer]

Thanks Mikko for testing my program!

I happen to have an input file for the Dyna-ship. This is a Dehler 33 with an increased draft (+ 60 mm), see attachment. It should run properly. The data was taken from Karsten Hochkirch's PhD thesis and also measured from an Rhino-file of the hull.

It seems that in your input file the waterplane-area is too small and in addition the LCF is rather forward. Therefore the program reduces the beam in the rear, which leads to the unrealistic stern. How did you determine the Awl?
Uli

Thank you Uli, I'm most greatful. I've been looking for the lines of the Dyna for quite some time, since it is such a well documented test case. Hence I started with Dehler 33 from my BoatBase, as soon as I saw Ulilines. I will certainly remember you in your donate-link.

I'll have to find a better way to estimate the Awl from the principal dims - any suggestions there?

 

[Mikko Brummer]

Your input file made a beautiful hull, thanks

 

[Remmlinger]

Thank you Mikko for your kind posting. It has significantly increased the visits to my website.
You also showed me a new usage of my program that I did not think of: Reverse engineering! But I have to point out that the hull that you created with my program still differs from the real Dehler 33. It is a specific characteristic of the Dehler 33 that the max. Tcb and the max. Bwl do not occur at the same section. This is something that I can not model with my program, where the main section has max. Tcb and max. Bwl. This seems not to be a big issue since I used the model from my program in a VPP and the results compare well with towing tank measurements.
Uli

 

[Mikko Brummer]

But I have to point out that the hull that you created with my program still differs from the real Dehler 33. It is a specific characteristic of the Dehler 33 that the max. Tcb and the max. Bwl do not occur at the same section. This is something that I can not model with my program, where the main section has max. Tcb and max. Bwl. This seems not to be a big issue since I used the model from my program in a VPP and the results compare well with towing tank measurements.
Uli

Ok - I don't think it's a big issue either. I reshaped the bow a little, and will add a keel and a rudder and plan to make a CFD run sometimes when I find the time. I already made an X-35 model I've also been missing for a while - simply brilliant!

 

[quequen]

My reverse-engineering attempts have been unsuccesful, maybe the Tcb / max Bwl is the problem? Many wide-stern monohulls have Tcb forward max Bwl. I'm trying with my own hull designs so I have no doubts about input data. Here an example (mini 6.5m). There is one more feet added to the stern (?), sternlines have a rare curvature. I need some orientation, thought!

 

[Remmlinger]

quequen, in your input file the LCF is forward of the LCB (LCF = 0.55 and LCB = 0.56). This is very unusual, you are asking for an afterbody with large displacement and small waterplane area. The program tries to fulfill your request and reduces the beam in the rear while keeping a large submerged volume. This leads to topsides in the rear that are bent inward. Changing LCF from 0.55 to 0.57 will cure the problem. The parameter TRANSOM = 1.0 will produce already a large transom. See attached input file. Hope you are content with the result.
Uli

 

[quequen]

... LCF is forward of the LCB (LCF = 0.55 and LCB = 0.56). This is very unusual...

Oops! my typing mistake, sorry. Now underwater lines fit very well! I still have some problems at the bow (out of water).
Hard to belive an entire hull can be rebuilt starting from as few parameters!
Thanks Uli, this is a fantastic tool!

 

[Mikko Brummer]

X-35 from Ulilines, very close to the real thing.

 

[Remmlinger]

Congratulations Mikko and Quequen for the realistic hulls!

It seems that I have to add an additional parameter for the bow-shape, so that the program can handle modern bows with a vertical stem. May be I will find the time during the coming holidays.
Uli