# how to compare the total resistance.

Discussion in 'Boat Design' started by sreenath00, May 2, 2009.

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### sreenath00Junior Member

Is there any way to compare toal resistance for round hull and flat barge of 100m length
30m bredth
6 m draft.

any formulas.....

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### mydauphinSenior Member

Resistance is same based on surface area. Which has less. But notice that shape of hull, Bow has a lot more to do than just surface area. A flat barge has potentially a vertical wall, the round hull more of a bow. Notice that flat barge may sit higher in water than round, therefore may offer less water surface. You need a computer or a be very good with slide ruler.

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### rwatsonSenior Member

In english that means that the total surface area under (in contact with ) the water contributes a lot to resistance, but the shape of the hull is even more important.

Gnerally a rounder hull means less underwater surface area for the same displacement, but some hull forms (like freighters) need stability more than reduced friction

You can get any naval architect to produce theoretical figures for you.

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### Ad HocNaval Architect

".....Is there any way to compare toal resistance for round hull and flat barge.."

With more information than just one line question, yes.

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### sreenath00Junior Member

thanks for you replay..
MAy iknow how to compare the resistanc for ships of same dimension one with round hull and another with flat barge....
Is ther any thumb rule like ...the total resistance for flat barge is some XX% > or < round hull....

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### petlilyJunior Member

There is a good reference on how to calculate the total resistance of a barge that takes into consideration the bow shape and hull surface;

Oilfield Publication, Volume 4, "Towing" by Michael Hancox, page 365-366.

There are formulas for Frictional resistance, wave resistance and wind resistance (hull & deck cargo) that sum up the total resistance in those pages.

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### sreenath00Junior Member

Hello Petliy,
Thank you very much for your valuable replay.Since I could not find this book nither in net nor in library ,can you pls send me a soft copy for "Oilfield Publication, Volume 4, "Towing" by Michael Hancox,"

My mail id is :sreenath008@gmail.com

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### petlilyJunior Member

I do not have the softcopy nor a scanner with me at the moment. Perhaps, if you google and get lucky enough, you might find a few pages of it.

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