# Easy calculations

Discussion in 'Software' started by kjell, Mar 25, 2006.

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### kjellSenior Member

Many times it is useful to have a simple program to calculate the most important factors for Displacement hull , Semi displacement hull and Planning boats.
Boat speed.
Power requirement.
Propeller size.
For the last 30 years I have been using a program made by me for resolving Speed , Power and Propeller problems on Yachts. It is in Spanish but it so easy to use. It is working with metric dimensions.

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### Tim BSenior Member

I agree, that's why I have a Delft series resistance code and Hazen's model. Other bits and peices to write include Savitsky, and Holtrop and Mennon resistance codes. Now if someone could save me the time and it didn't cost me a fortune, AND it ran under Linux I might be quite interested. Naturally, you'd have to do it before I'd finished writing it.

Tim B.

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### kjellSenior Member

Displacement hull calculation.

To calculate the boat speed and needed power you only have to introduce the LWL in meters and the Weight in ton.

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### kjellSenior Member

Semi- Displacement hull calculation.

To calculate the boat speed and needed power you only have to introduce the LWL in meters and the Weight in ton.

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### kjellSenior Member

Planning hull calculation.

To calculate the boat speed with the power have you only have to introduce the Weight in ton and the engine power.

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### kjellSenior Member

Propeller calculation.

Based on the speed and power calculation it is easy to calculate the propeller.

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### CGNSenior Member

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### kjellSenior Member

This program can be yours free.

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### Tim BSenior Member

Yes...

I think the alpha version of DSRC and even the savitsky spreadsheet that is around might be just slightly more advanced than the resistance algorithm. Certainly the Holtrop and Mennon method requires a little more data.

As for the propeller design, It could be very useful, but quite often it is just as easy to work off a propeller chart, unless specifically designing a propeller, in which case we use the big letters....CFD.

I'm not bashing your work, but for most design purposes we need an accurate (preferably tank test checked) piece of code.

Tim B.

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### kjellSenior Member

I am now 72 years old. I have been working for over 30 year in Mallorca Spain resolving propulsion problems on yachts up to 30 meters. The need of to have a calculating tool with an easy way of verify Boat Speed Engine power and propeller size. I collected the formulas from the best Marine Engineers and added them to this program. I would like that this Tool continue in the hand of other Marine Engineers around the World. That is the reason why I am giving it free.
This program covers calculations of Displacement, Semi- Displacement and Planning hull. With this program it is possible to verify if your boat are making the Speed or if the Engine power is sufficient or if your propeller is the proper size. The accordance is over 90% and has been tested by many Marine Engineers. The program is made in Spanish and in metric system. Translating the different Data input to your Language it is very easy to use.
Kjell Dahlberg

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### Tim BSenior Member

Would you like to post the source-code? I'll have a look at translating it for you

Tim B.

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### kjellSenior Member

Free CD

I can’t email the source-code to you so pls. give me your post address and I will send you a CD by post. I can include an English handbook if you don’t have a Spanish Dictionary.

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### kjellSenior Member

The Power Factor Method for Calculating Propellers in my program
is based on the BP delta Method

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### DavorNaval Arch.

Try my demo-program SeaPower www.sea-power.net

Davor

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### Tim BSenior Member

kjell, Sorry I haven't e-mailed you, I got the code and I'll have a look at it in the next week or so (I hope).

Cheers,

Tim B.

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