design verification

[fadgadget]

Hello over there

I want to build a 40-50 foot racing dayboat / weekender. Classic lines and modern equipment. Something beautiful to look at, fast and elegant to sail, lets say something like a scaled up dragon.
I also want to design the boat myself although I am not a naval architect.
I have already drewn some designs , but never builded any of them. So I don't know if it will sail good or that it is seaworthy...
I think, to have it designed by an architect is always better, but I am familiar with drafting, designing and 3D CAD, and I would like to do it myself. It just makes more fun to me. So is this although a stupid idea to risk so much money ?

Is it a good idea to put it into tank testing to have some verification of the design, and what does this cost ?
Is there software to evaluate this or are there experienced proffesional engineers who can evaluate the design for a reasonable amount of money?
Or does anyone has a better idea ?

[chandler]

Read,Read, read and just do it

[D'ARTOIS]

Ask Eric Sponberg - he has a boat - design that will fit 100% - I had a swiss customer once that was highly interested - just then he arrived in some sort of banking problem and the issue was off.

[tspeer]

I would team up with a NA.

What you're really doing when you work on your own design is creating a very detailed set of requirements and getting a good understanding of what those requirements mean for the design. It lets you talk to the NA in very concrete terms. If you plan to build the boat yourself, then presumably you will be doing much of the detail design as you go along. The NA can help you figure out these details ahead of time, saving time and cost by smoothing out the build process.

After all, do you want the best boat you can design, or do you want the best boat you and an experienced NA can design?

[cyclops]

Save a few lives at sea. Copy a proven design that is very close to what you want. Then modify with the designer. You will not be turning away from the dark clouds every time they appear. Use the designer!!

[Stephen Ditmore]

This book is intended for people in exactly your position:
www.cornellmaritimepress.com/3917.htm
It advocates doing the preliminary design yourself, then taking it to a naval architect for finalization.

You could try to interest a naval architecture student in working with you as an intermediate step. Ask at:
www.ocp.tudelft.nl/mt
www.marin.nl
www.solent.ac.uk/courses/undergraduate/yacht_and_powercraft_design_beng/course_details.aspx
VPP and CFD computer programs are now good enough to be a better buy than tank testing for analysis and development, in most cases.

I encourage you to find someone in your area to advise you. In particular, I think you should contact Van de Stadt.

I've broken down the links below by area.

Netherlands
www.stadtdesign.com
www.sheevra.com/sailing.htm
www.stadtdesign.com/products/vds609_D.htm
www.stadtdesign.com/products/vds635_D.htm
www.stadtdesign.com/products/vds547_d1.htm
www.stadtdesign.com/products/vds647.htm
www.gdnp.nl
www.oossanen.nl
www.simonis.com

Northeast U.S.
www.brooklinboatyard.com
www.scaranoboat.com
www.gannonandbenjamin.com
www.zurnyachts.com/sail.html (note Zurn 53 design)
www.fontainedesigngroup.com/news/index.asp?ID=12
www.hinckleyyachts.com (Check out the Hinckley DS 42)
William C Frank Offshore Yacht Design, 5 Topsail Rd., Rowayton, CT 06853 (no web site)

Western Canada
www.tadroberts.ca

[Robjl]

I use "Principles of Yacht Design" by Larsson & Eliasson and a Cad Program "Prosurf" at www.newavesys.com I think they still have a free download.
Good luck

[fadgadget]

Thanks for the many useful ideas and links

I just ordered some books about the topic.
I am afraid that when I take an advisor or NA after I did some design work, that he will like to start over again on his own design. Whether it is good or bad.
I already experienced this with designing and building my own house. With this I finaly took an architect who drew over the plans and signed them for agreement ( it is part of the law at my place that an architect agrees with the construction ) It costed me a lot of money. So I builded it my way and although some things could be better or in an other way, it is a very good and goodlooking house. I still get some nice compliments every time someone comes to visit.
I agree with taking a good and experienced advisor from the beginning of the project, someone who can look over my shoulder and prevent me from making mistakes. So I have to find someone who is interested ... ?

For the moment I am building a dingy ( bought the plans :) )but when this is ready I start on the job

[FAST FRED]

House architect's are famous for wanting YOU to build and live in their "Personal Statement" , to hope to get another sucker comission.

Boat designers are quite used to very very experienced owners with specific needs and demands. NO PROBLEM!!

My problem is with probably a million designs to chose among what is so special and particular that YOU MUST have that isnt already on someones shelf?

A Great NA will charge about 10% of the total vessels cost ,

a lot extra if its just a another boat.

FAST FRED

[D'ARTOIS]

Fast Fred, 10% I believe is a bit exaggerated - no architects in Holland (or US) - save for Farr & Ass., Van de Stadt, Dubois etc. - charge that sort of money.
Generally in Holland costs are around 2-3% max.

Where you are right is that when a customer goes to a NA, with a specifical boat in mind, this ( sucker ) client pays the full bill en than you might end at something like 5-8%.

If you go to Farr, you might rest assured that you will pay for a 20 mtr racing yacht a good USD 1000 BIGS. If I say BIG it is the biggest banknote in the normal exchange. ( Banks do have higher notes for their internal traffic use )

[Stephen Ditmore]

The first three U.S. links I gave you are design-build operations, not big name design offices. Brooklin Boat Yard already builds a boat similar to what you describe: the W-46. They've built three.

One thing I wonder is whether starting with the W-46 scantlings & weight study wouldn't be a big time saver. I think it's worth discussing with Robert Stephens. If you can't come to agreement, no harm done.

Concerning velocity prediction, I'd start with http://www.schwenn.com/ or someone who offers similar services (check with hydrodynamics labs in your area).

There are engineers who develop scantlings and laminate schedules for other designers. Which one I would recommend depends on the construction method. What material will you be using?

[chandler]

The w46 is a gourgeous boat! If you want to spend a million dollars. Stephen do you think Brooklin Boatyard would sell those plans? Isn't that kind of an in house proprietory plan?

[Stephen Ditmore]

Could be... but it doesn't hurt to ask. Certainly Stephens himself would be free to utilize W-46 information if hired to consult on another project. There are other options, but having some basis for the weight study is important, as is having a starting point on scantlings & other issues.

Here's a firm that many production builders are turning to for development at a reasonable cost:
http://www.seaway.si/
Mark Mills hires out his engineering to John Fox <FCSdesign@compuserve.com>
Jim Antrim does the engineering for Wylie & others
Dirk Kramers...
GMT
Suppliers like SP Systems & Gougeon Bros...
Consulting services can be purchased.

Some things can be learned from studying historical plans, from Herreshoff & others. But it has to be applicable...

[sharpii2]

Boat designers are quite used to very very experienced owners with specific needs and demands. NO PROBLEM!!

My problem is with probably a million designs to chose among what is so special and particular that YOU MUST have that isnt already on someones shelf?

A Great NA will charge about 10% of the total vessels cost ,

a lot extra if its just a another boat.

FAST FRED

I would agree, Fred, if bang for the buck were the only issue. Just find something that is close to what you want, then just purchase the plans.

But, even if they guy ended up with 'just another boat' from our point of veiw, he would have gone through the life affirming proccess of learning all the compromises needed to come up with a workable boat.

What we then have here is a sense of empowerment that even the rich really rarely have. How many of them, like us, just follow the leader. The fact that they have a bigger wallet to do so makes little difference in the end.

Also, the fact that he intends to build the boat himself puts yet another wrinkle in the fabric. The boat will have to be designed around not only his skills to build it, but his favorite matterials as well.

When I was in school, there was a fellow student who took the course so he could design his own boat. Various learning disabilities made him unable to master some of the basic concepts of the course. After a mighty struggle (he was often there 16 to 20 hours a day) he was forced to withdraw from the course.

The instructor offered to help him design his boat. I often saw the two of them working together many hours after class (where I was struggling with my own problems) and seing my instructor apply his engineering knowledge, as well his many years of experience in the field, to this young man's dreams was really quite moving.

I don't know if the boat was ever built. I don't think it really matters.

What matters is that this young man was able to leave the school with plans for his dream ship in hand rather than a sense of humiliation and failure.

Bob

P.S. If this were a union hall, you would be thrown out on your kiester:)

[fadgadget]

Hi guys, a part for which I want to do it myself is learning from it and creating something personal. I am a professional product designer, so I am not unexperienced in the design process.
What do you experienced boatdesigners / builders think is most critical or demanding in the process? Or what items should be given much / or the most attention to, to get a good sailboat?
It is certainly necessary to involve a NA or someone with a lot of experience into the designing process. Meanwhile I want to learn and study as much as possible on the topic to get it right...
For building material wood stripbuilding comes as a first choice, GRP sandwich construction as a second.

[Stephen Ditmore]

Olin Stephens spoke to my class at the Landing School in early 1991. I think people (I among them) were expecting him to talk about how to design a low drag, race winning hull shape. Instead he led off by saying (this is from my sometimes slippery memory):

There are priorities that ought to be kept straight when designing any vessel. The most important thing, it seems to me, is that a vessel be strong enough. The next most important is that it be stable enough. And a bit farther down the ladder, but still absolutely necessary, is that the craft be controllable. Everything else, drag reduction and what-not, must come after those three things, and a designer's time and attention should be allocated accordingly in all but the very rare case.

Cyrus Hamlin's book (see my post #6 in this thread) continues the theme of priorities and the "design spiral".

[D'ARTOIS]

The era (very unfortunately) of Olin Stephens is over. Nobody from the old guard can tell you how to design a today's winner.

Some of our US friends have pointed out - in different posts - that it is absolutely not necessary to be the inventor of the wheel again.

There are a few steps to begin with:


0) make sure that you have the required budget;

1) Fix your building material;

2) establish LOA and Bmax;

3) a sailing boat has several centers of gravity - check with a NA;

4) go for the maximum draft;

Look at the design of Ed Burnett mail@burnettyachtdesign.co.uk
that bring maybe some (expensive) ideas:cool:

[Stephen Ditmore]

I'm not sure on what basis D'Artois thinks Burnett is less "old guard" than Stephens, but here's a Burnett design that might be similar to what Fadgadget has in mind:
http://www.burnettyachtdesign.co.uk/112sloop.html

[chandler]

Stephen, Were you an instructor or a student at the landing school?
I don't think you can get much more traditional than ed burnett. Old guard? meaning long overhangs and beautiful proven designs? Anybody in here that thinks they can criticize sparkman and stephens should take a look in the mirror and throw away the computer.

[chandler]

D'Artois,
I'm not sure of this but I would venture to say Burnetts most profitable and popular design is the collaboration with Irens on a shoal draft coastal cruiser,"Roxane and Romilly", certainly the minimum draft.

[Stephen Ditmore]

Stephen, Were you an instructor or a student at the landing school?

Student.... design class of '91.
Full disclosure: Cy Hamlin, whose book I mentioned, was one of my teachers, and I worked for 3 months for S&S in 1997.

BTW many S&S designs are available from the Mystic Seaport Museum Library, where S&S sends them after a certain amount of time. Herreshoff's designs are held by MIT... I think it's called the "Hart Collection."

[chandler]

I was just curious. I live nearby and have some associates that are either graduates or graduate/instructors.
Please excuse the spelling, getting kind of late...:)
None of the people I know are currently working in the trade.

Good for you pursuing your education. Hope all is going well, be interested in your input for a design I have in the works. How's Hamlin? Any idea? Does he still live in Arundel? Do you suppose he would be intertested in critiquing an amatuer design?

[Stephen Ditmore]

I'm not making my living in the trade at the moment either. Just building a Classic Moth and trying to stay current. I have some thoughts of developing kit designs after I've raced the Moth for a while. I think I'll be happier designing on a small scale than trying to separate millionaires from their money.

In the late '90s Cy Hamlin took on a young partner. I haven't checked up on him since.

What's your design?

[chandler]

Steve,
It's an enlarged version of Irens Roxane, featured in woodenboat in 95 or so.
I understand what you say about the millionaire thing, however there's lots of us working folk looking for affordable cruising designs, I think Bolgers proven that.
Chandler

[tom28571]

The Morris 36M seems to be the kind of boat you are heading toward although smaller. http://www.morrisyachts.com/morris36.html

There are a couple others that are new to the market and larger but I can't think which they are right now.

[fadgadget]

Well indeed tom 28571 it got to be something like the above mentioned yachts, but than completely different :-)
That is a bit of the point to. There are so many yachts, with all different lines, forms and details, and they all sail very well.
And if you respect the hydrofysics and don't do crazy things,and if you compare your own design to that of others, I think you can't do much wrong in my opinion. But it would certainly help do have a little certainty of what you did is right, and that was the question ... So what things can help me verifing my design?

[Stephen Ditmore]

Engineering: Get with someone good. Alan Cattelliot at Multiplast would be an example near you. You could also take a look at software like HullScant <www.wumtia.soton.ac.uk/software.html> so you can work the tradeoffs yourself in the early going.

Hydrodynamics: Have an experienced person run several candidate hull/appendage combinations through free surface CFD software like Splash <www.panix.com/~brosen>, ShipFlow <www.flowtech.se>, or Michlet <www.cyberiad.net/hullsoft.htm>, and input the values into a proven VPP (velocity prediction program, basically an overall lift/drag sum-er/equilibrium solver) such as Velocity <www.schwenn.com> or WinDesign <www.wumtia.soton.ac.uk/software.html>. Raceboat designers who've already done this many times have an edge. Tops in Europe are Botin+Carkeek in Spain and Judel/Vrojlik in Germany.

On these process questions, Peter vanOosanen <www.oossanen.nl> is top notch (though as the final decisionmaking designer, his own designs haven't won much). You could also check with www.wumtia.soton.ac.uk, www.marin.nl, and other hydrodynamics labs.

Remember I said you can hire a designer as a consultant rather than as principal designer? Check out www.owenclarkedesign.com/default.asp?m=da&id=11201

America's Cup skipper Russell Coutts <www.russellcoutts.net/RC44/PressRelease.html> is apparently becoming a yacht designer. I suspect he knows a thing or two about optimization.

You could also purchase and learn to use CFD and VPPs yourself, but the time investment would be big. You should be able to hire someone to run multiple candidate designs for you for less than tank testing a single design. As I said before, finding a student who wants to put time into learning these programs anyway might be a good value proposition.

When looking at optimizing you should be very clear what the parameters are. The exact question you ask will have an enormous influence on the answer you get back.