Help me to start

[Panos_na]

Hello everyone!
I am a new member in the forum and i hope that you will help me in many subjects about designing and building boats.

I will get straight to the point.
I want to design and then start to construct a sailing boat.It is the first time I am attempting to do something like this, and i have some questions.

Firstly, I have completed the body plan, lines plan and profile plan of the boat, but I dont know where to draw the Designed waterline. Do I have to calculate the Hydrostatics first?
I think that i have to know the Designed waterline before i calculate the hydrostatics.

Do you think that maybe i should construct a scale model of the boat and test it on water, so i can get the information i want?

I hope you will help me!

Thanks a lot!!!

[ars-technica]

To have the waterline,you need to know displacement of the boat.
You have to fix all weights.

[Thunderhead19]

Actually, the hull should have been designed from the beginning with a desired waterline location in mind. Then you do the hydrostatics, then you do the structural, then you do the preliminary electrical,plumbing and machinery, then use that to get your weights then adjust the waterline, or the hull shape if you have to. Then go back and adjust your structural, then your electrical,plumbing,and machinery, then do it all over again, and again, and again.

Hey! I would appreciate hearing from some more experienced people on whether or not my method is nothing but madness.

[Panos_na]

First of all, thank you for your interest.

If i finally find out the displacement of the boat, which is the next step?

[Danielsan]

I think getting the center of gravity of all components together,
position your boat in the coresponding angle downwards(perpendicular to waterlevel.)
Then calculate the volume of the boat that coresponds to the displacement the upper level of that volume is the WL.

I hope you getting what I want to say?

If this is not the right way please someone let me know!

Greetz,
Daniel

[Ilan Voyager]

I counsel you to read some books about sail boat design. The answers you'll get here will be too fragmentary as we are in a forum.

There are many excellent, but my prefered is "Design of Sailing Yachts" by Pierre Gutelle. The methodology of design is detailed step by step with examples and calculation sheets.

in Europe you'll find it at Amazon UK at £28.95.
http://www.amazon.co.uk/exec/obidos/ASIN/0948646543/wwwlink-software-21/202-5227639-5723823

[PAR]

I'm glad someone said what was needed, tactfully, I may have been a bit harsher (thanks Ilan) In addition to what he had to say, I'd strongly urge you to bone up on the design process through a course or books. The subject is quite complex, requiring large doses of advanced mathematics, physics, artistry and most importantly experience. In this I suggest, that a well educated person with a good grasp of the skills involved (basically an engineering degree) can design a safe, stable and fine performing craft that is butt ugly. This is where artistry and experience come into play. Frankly I enjoy the artistry aspect of it the most, the ability to set afloat a fine performing work of art (that floats exactly where I was praying it would, just before it was splashed for the first time)

Thunderhead19, yes, it's madness, sheer madness, but frankly the world needs us madmen, if for no other reason then to remind others of how lucky they are. By this I mean, anyone who's done center of masses calculations (the old fashioned way, without computer) truly understands madness.

My copy of "The Design of Sailing Yachts" is a reference I use to refer to quite often, but this issue (first one I think, with forward by H. C. Herreshoff) is a bit dated being completed in '79 I believe. Fastnet of that year had stunning ramifications on the current thinking of the time and many advances and changes in thought on the various issues concerning the design elements for a sailing yacht.

Use the "SEARCH" thingie in the upper right hand corner of your screen and look for "yacht design" You may have better luck with this using an online book seller's web site search tools.

[Panos_na]

Thank you once again all of you that you replied to my question for help.
I think i must finally buy some books, in which i will get all the information i need. But i think most imprtant is to ask YOU, because many of you may already have designed and constructed a boat of any kind.
What i am looking forward to do, is to design and construct a simple boat,(that will be able to float), in order to gain some experience from the hole process.
I dont want to construct the ''Perfect Boat'', since it is my first attempt, but i think that it wiil be a great experience and even if i do many mistakes,i think that these mistakes, will help me learn in order not to do the same mistakes in future.

Thank you once again for your interest and i wish you will help me a lot in many questions and problems i may have in future.

[Ilan Voyager]

You're welcome.

For a small simple sailboat like a dinghy, you need only to make fairly primitive calculations.

Look at sail boats of same size to the boat you plan to design and build and examinate all the details. The best tools for this task are a measuring tape, paper and pencil; so you can take notes of the important details.
Download the few free plans you'll find in internet, and examinate them with a critical eye.

A simple day boat will be the best for a first one. Make a search in internet for Bolger, a very (too?) prolific boat designer. There many sites.

A lot of his boats are truly horrible boxes, but I apreciate his philosophy of straight simplicity and some of his creations are interesting.

PAR is right; put some artistry. A nice elegant line changes all.

[sorenfdk]

Gutelle's book is good, especially the second edition, which, by the way, is hard to find.
Other good books are:

Kinney: "Skene's Elements of Yacht Design"
Larsson & Eliasson: "Principles of Yacht Design"
Gerr: "The Elements of Boat Strength"

The first two can be considered the old and new testament of yacht design, and Larsson & Eliasson is, I think, a must.
Gerrs book is mentioned because no matter how beautiful your design may be, it still needs to be strong enough.