# Resistance Prediction with statistical methods

Discussion in 'Hydrodynamics and Aerodynamics' started by vaer, Aug 1, 2018.

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1. Joined: Aug 2018
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### vaerNew Member

Hello everyone,

I am currently working on a university project where we want to calculate the resistance of a hull with statistical methods. At the moment we just have the main dimensions of the boat and some 3D hull designs.

Lenght: 9 meters
Width: 2,5 meters
Displacement: 5 tons?
Field of application: river

The goal is to compare the resistance of different hulls (mono and catamaran) with statistical or other methods and then decide for a hull design. Beside of the statistical claculation there will be a CFD simulation in fluent ansys.

I already implemented the Holtrop/Mennen and Hollenbach method in matlab. But the problem is that these methods are for large ships and we want to design a river boat.

I wanted to ask you if you could help me to find the right methods for this problem.
I already found the Free!ship software to do this calculations (Holtrop/Mennen) and the Free Delftship, so it would be really nice if there is a software to calculate the resistance, otherwise I will try to implement the method in matlab and I could offer you the finished function if you are interested.
What kind of methods would you suggest to use for resistance calculations of a small motor boat?

Thank you very much for your help and have a nice day,

Greetings from Austria,

Valentin

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### TANSLSenior Member

Better than large or small boats, the Holtrop-Mennen method applies to ships whose parameters are within these limits.

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Welcome to the forum Vaer,

Your hull has a length-displacement ratio of just 5.3. Thus you really need to centre your focus on published R&D of hulls that are of the same order of magnitude.
The classic Bailey series for example, would be a good start.

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### bitStudent

Hello.
There are parameters for almost any type of calculation (Tansl reported Holtrop).
By posting more data.
These I have in Excel

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### vaerNew Member

Thank you very much for your replies, you are helping me a lot!

We are currently at the very beginning of the project and are trying to acquire shipbuilding knowledge, so please forgive me if I use nautical terms incorrectly or write wrong things.

The boat will be a passenger/ferry boat for about 16-20 people. The speed will be around 9-12 knots. So I think it will be more or less a displacement or a semi displacement hull. The propulsion will be electrical.

To get a better view, here some links which sho the direction of the boat:

http://www.allmandboats.com/images/38BB/enclosed_cabin_catamaran_watertaxi_1.jpg
http://img.nauticexpo.com/images_ne/photo-g/58033-8319898.jpg
https://encrypted-tbn0.gstatic.com/...GBh1ab_qfKSI_Wo8-0REtSVHA4XCgtP-OHwIDkvk-SY12
http://www.seaspeeddesign.com/images/coral2054_000.jpg

@TANSL: Thank you very much for this information, it is very difficult to find information about the range of application of the methods. I see that you own a company which is specialised in naval design and you are from spain, the project takes place in colombia, so maybe there could be a cooperation if the project is more advanced.

@Ad Hoc: Thank you very much, i found this docoument, its the NLP Series by Bailey, 1976:
https://www.boatdesign.net/attachments/npl-pdf.93909/
I will have a look!

@bit: Thank you for this nice overview, that will help me a lot to find some methods to use and to compare them. Do you may know some software where the methods are already implemented? The excel file you have is commercial, or did you implement them by yourself? Would be a great help but I totally understand if it is not possible to share or if you don't want to share your work

Thank you very much for all the help and informations,

Valentin

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### TANSLSenior Member

I would be happy to collaborate on the aspects of naval architecture of your project, if you need it.

#### Attached Files:

• ###### Holtrop.zip
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76.8 KB
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### gonzoSenior Member

The target speed is very important for the comparison. I think that you can also generate graphs of efficiency, motion comfort, etc. for different parameters, but will be much more complicated. A single speed would probably be adequate for a project.

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### Mr EfficiencySenior Member

If electrical propulsion is de rigeur, then the endurance will be the key factor, what distances need to be travelled, what facilities for recharge and time available between trips etc. It will be a big ask to be going far, at faster than a crawl, with electric propulsion.

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### bitStudent

Hello
I Implemented by myself, copying all the regressions so as not to need diagrams or figures. The results come automatically.
If you need a comparison (only one) it's free. Optionally.

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### vaerNew Member

Hi,
thank you for all the replies and the excel spreadsheet. I did a research on all the standard series and there is also a lot of information in "Ship Resistance an Propulsion by Anthony F. Molland.
I found a lot of papers and also some excel calculation spreadsheets here in the discussion board. The goal is to simulate an energy model in matlab. Therefor i need the resistance and propulsion prediction to calculate the energy consumption.

I have now calculation programs (excel, matlab) for this methods:
Hollenbach
Holtrop - Mennen
Mercier & Savitsky
Compton Round Bilge and Hard Chine
De Groot
Newman

@bit: Could you suggest me some methods for semi-displacement round bilge ships which are easy to implement? And also for Mulihulls? That would be a great help for me before I start reading all the papers...

have a nice day, kind regards

Valentin

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### vaerNew Member

I started now with implementing the Southampton Catamaran Series and the VWS Catamaran Series in Matlab.
You can see the results of the total resistance to the speed in the attached picture. The VWS result seems legit to me, the Southampton results seems to be wrong.
What do you think? I started with the implementation with the help of the Molland Ship resistance and propulsion book.

kind regards, Valentin

#### Attached Files:

• ###### catamaran resistance.jpg
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46.2 KB
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### Mitch1990Junior Member

Hi Valentin,

Are you able to share the excel/MATLAB for the Mercier & Savitsky method?

Mitch

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### DCockeySenior Member

Valentin's last post was in August 2018. He may no longer be reading the forum.

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### Mitch1990Junior Member

I did think that, but figured it was worth a try.

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