# Question on hull mathematics

Discussion in 'Hydrodynamics and Aerodynamics' started by DTurnham, Sep 15, 2014.

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### DTurnhamJunior Member

Hello, I am new to the forum and to boat design. It's something I have been very interested in for many years but felt out was something I could dream of doing but never actually do. However, recently i have decided that life is too short. Anyway, I have decided that my goal is to enroll on a boat design course with Westlawn or YDS. Before i enroll, though, i thought it prudent to buy a couple of books on the subject and learn what i can from them. I have been reading Skene's Elements of Yacht Design and taking some notes to enhance my understanding. However, although I have been following it well, i think i have been let down by my bad mathematical education. The Simpson's an Trapedoizal rule sections were fine finding both areas and centres of gravity. Where i struggled easy with finding the area of wetted surface of hull. I have read through the method three or for times and cannot grasp it. My question is, does anybody know of a website or something where the method/s are explained in simple terms so a beginner can learn to follow them? (Taylor's method etc). I am not intelligent, but its been a long time since my school days and like i .said, the maths education i did have was basic to say the least. Any help would be gratefully received. Thank you.

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DT

Welcome to the forum. Sounds like you have taken a lot on-board from the beginning! Unfortunately a command of maths is essential in naval architect/design, so, just be patient.

Perhaps the first would be to get a simple book on basic maths to re-educate yourself and slowly learn some of the higher level maths that is required. Second, an introduction to naval architect, by Tupper, or Teach yourself Naval Architecture by Brian Baxter (new edition or older one) will show in more step by step way of using Simpson's rules. If it still causes problems, then it may suit you to seek someone locally that cabin sit down with you and explain face to face.

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### DTurnhamJunior Member

Thanks,ad hoc . i have seen a couple of 'maths for dummies' books. which branch of mathematics includes these methods?is it calculus/triganometry etc?

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DT

Yes, it will cover all the bases. That would be a good book to start with too. Dont read it cover to cover like a novel. Just go the basic parts and redo them several times until you feel comfortable with the subject. Then move on, as an when required.

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### JSLSenior Member

You are off to a good start and don't beat yourself up too much... you are asking questions and that is a sign of good intelligence.
Wetted surface uses girths with Simpson's rule and multiplier of a length factor as Skene's mentions. The measuring is done with tick strips but I have used a flexible curve. Best, to take the course(s) and let them teach you the correct way of doing it.
Yes, you can get good help on-line at web sites but you can also get poor (incorrect) help as well.

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### Leo LazauskasSenior Member

I would also recommend free online maths lessons (with videos) at the Khan Academy.
It covers everything from early kid's stuff to University level.

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### rxcompositeSenior Member

DT

Some of the Wetted Surface Area (WSA) are simple arithmethic while others require a coefficient to 6 decimal places. Taylors method require a rather difficult skewed circular graph. Practice on the easy ones first, as explained by Tupper. The more difficult ones appeared in Principles of Naval Architecture. I will post it again for you to practice on.

#### Attached Files:

• ###### Wetted Surface Area.xls
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### jehardimanSenior Member

Since you already know Simpson's rule, it is fairly easy to get fair +/-1% answers as JSL says. If you don't like tick strips, walk the section perimeter with a pair of dividers (proportional if you have them), then plot it like a sectional area curve and use Simpson's, Tchebycheff's, or a planimeter.

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### DTurnhamJunior Member

Guys, thank you all for your advice and encouragement. can anybody su
ggest specific branches or methods of mathematics that i should study which are most relevant?

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### Leo LazauskasSenior Member

Trigonometry
Basic Geometry
Algebra 1
Pre-calculus