Art/Design student requesting help.

Hi I am currently an art student in college and one of my assignments in a 3D design class is to create a functional piece of art that is graded in three categories Aesthetics, Functionality (as tested on a scale model most likely on small lakes and lake Michigan nearby, stressing it until catastrophic failure i.e. capsize or hull breakage), and Craftsmanship in the design drawings/scale model. I have chosen to design a sailboat. I am allowed to research and get advice but the design must be ultimately my own. Since I don't know anything about designing sailboats or even sailing them I was wondering if someone with more experience could give a quick glance at my initial rough draft of the hull shape. I realize boat design is all about compromises and would just like to know what its significant advantages and disadvantages would be. Also Im not sure about mast placement. I have attached the images and would be eager to hear any constructive criticism that you may have. This is still a rough draft and is open to major design changes. Thank you in advance.

 

Oh boy. I don't know if you know quite what a big subject that is.

Aesthetically I guess that's quite a pretty set of curves, but I fear in no way does it constitute a basis for a working sailing boat.

I honestly don't know where to start though, because although I've written a fair bit about how an amateur (like me) might go about designing boats in the past, I've just taken a look at some of it, and its all assuming vast amounts of background which it would appear you just don't have. Sailing boats were arguably amongst the most complex machines of the pre industrial age (let alone what they've become since).

Basics: a sailing boat works by the interaction of the aerodynamic shapes and forces above the water (sails) and hydrodynamic forces below the water (centreboard/rudder/keel and to an extent hull shape). For it to work *at all* you need to have at least a decent rule of thumb understanding of how that all interacts. I don't think we can teach you all that science, nor, really, would the time spent doing it be of much value to you.

Perhaps you should rethink your project into something a bit less ambitious?

 

Look up boat designs and lines. They will give you an idea of what they are supposed to look like. What you drew would not make a good boat. Boat design is largely about engineering more than cosmetics; they come second. Learning how to design a sailboat is the equivalent to a college degree. Maybe you are biting more than you can chew.

 

I would suggest Brewer's Understanding Yacht Design to start with. It isn't terribly technical but covers some of the basics inCluding some styling advice. On line you can find "The Design Ratios" by Sponberg for free and it will cover more of the technical details the Brewer touches on.

You need to pay attention to the sheer line in particular on the style side.

My own experience suggests that an old program, HullForm 9, may be of use to help develop fair lines that can be taken over into programs capable of producing prettier pictures. This is because HullForm is not a NURBS program but rather draw a the lines through cross sections. So with a few known points you can get intermediate points that the program will smooth into a fair line. Of course if your 3D program has that feature you might not be interested. One thing though, HullForm does have a fairly complete statics capability, including the ability to assign a heel to a boat. It is certainly useful to help visualize changing waterlines using the program.

As it's not a NURBS program there isn't an exact translation between it and something like DelftShip or FreeShip, though it will export VRML files that DelftShip can import (be ready to rotate the file because the programs use the axis differently), but it's close enough model vs model to get an idea what your hull in another program may be like.

DelftShip, when using traditional units, uses long tons (2240#) in its hydro statistics reports.

 

Welcome to the forum Patrick,

the book "the Nature of Boats" has a lot of simple design ratios and explanations of how boats work and why. It would be a good way to start, and give you enough information on designing a simple dingy that will behave well. I would think most larger libraries have it.

you can also follow and read through this thread and learn a lot about designing a boat (it is as big as a book and not organized as well). http://www.boatdesign.net/forums/boat-design/melatelia-light-wind-dinghy-52831-16.html

good luck.

 

Thanks for the book references and the program that is certainly what i was looking for its appreciated. As for the other comment Im not designing anything a human being will ever be in just a 1/12th scale model and I'm really only competing against other art students so the smug dismissive comments aren't really helpful. My last assignment was to build a suspension bridge so the elitist response telling me to get a masters before i make a model that is supposed to fail just shows that since you can't explain something simply because you yourself do not understand it considering you are unable to explain what the major concern would be (not that I'm saying it would make a good boat) but I was just asking what the major flaw in this design would be. So that i can go back to the drawing board and make changes. But I should have expected as much from an internet forum.

 

Go find some other sailboats and copy their general shape. Look up, say "Cape Dory 25" or "Gaff Sloop Plans" or, a little different design, but my favorite for beauty, "J class Yachts" and "Skerry Cruiser". Good luck! It shouldn't be too hard to make something that looks reasonably nice and sails alright, you just have to copy the real world.

 

Since it's just a study problem, rather than anything with a valid engineering approach, I'd suggest you go way out on the design "limb", as there's no real lose. If you show up with something well modeled and way out there aesthetically and conceptually, you'll have a big advantage come grading time. Simply put, attack the design of the exercise with a bold stroke, rather than any conventional swing. This places the instructor in an awkward position, to judge your project on the aspects of the problem definitions, in stead of its value as a viable structure. Of course, this assumes it'll hold up fairly well come testing time, so make it pretty stout too. I'd look at a trimaran with swoopy wings and stylized main hull. Don't use conventional shapes, do nearly everything a bit different.

 

Oh thanks the Trimaran is a great idea from what I've read (and correct me if I'm wrong please) All i have to do is keep the hulls narrow and long and they should be alright. Which keeps a bit of the math out of the equation for me i just have to make sure they displace enough to keep the overall weight afloat and keep em narrow. I think. That Skerry cruiser is beautiful though Anyone know of a slightly smaller boat that looks similar? Like in the 20-30 ft range?

 

You're either a glutton for punishment or you have not very much appreciation for the complexities of this world. The two areas you have mentioned (bridges and boats) have historically attracted some of the most artistically creative engineers of history. And there are huge sums of money involved in both enterprises.

I would suggest that if you do not have the university's engineering dept. at your disposal, you should concentrate on less engineering intense products, and pehaps less mature ones that don't have centuries-old worldwide standards institutes dedicated to their design and safety and insurability.

How about a decent slotted spoon for the kitchen. Or a pooper scooper that is both ergonomic and functions - currently the are are a couple that do one or the other, but none that do both. Easier to test at the local dogie park than Lake Erie.

If you stick with a boat, you will be judged against the International standards governing boat design, at least around here.

Perhaps the following? Find or build a stock model of a Herreshoff H28, then restyle it and compare the two? It has been fiddled with by many over the years, mostly with bad results. Tons of photos available, and they are an endearing craft and a handy size for 1/12 model.

 

I didn't arbitrarily pick it. it was one of a few i could choose from most likely picked by the professor because of its complexities. Im merely trying to make an honest attempt within the allotted time. He most likely expects most of us to not succeed fully. If it fails no worries its just a model no one is belittling the profession of serious boat design its just a students project I understand its not something a person can do without extensive training if they are going to make something full sized with human passengers. It would be unethical to build without proper training. But like i said its a model. its not that serious.

 

Certainly when you look at those trimarans there's a lot of possibilities in nice curves and interesting shapes.

Another source of inspiration for this sort of project might be Manfred Curry's Aero from, amazingly the 30s, and still looking ahead of the game in many ways.

http://www.minisail-ev.de/mb/mb-11-06/mb-11-06.htm

http://www.classic-modellyacht-design.de/Schwertboote/Rennjollen-1918-1945

Long and thin is definitely the way to go for interesting sweeping curves I think.

There's also the practical point that if you have a long thin boat with a keel under the sails and a rudder a long way back its relatively easy to make it work after a fashion. If the centre of the sails is roughly above the centre of the keel it will look roughly right.

 

Stop getting caught up in stuff that isn't part of the exercise and focus on the criteria.

Functionality is pretty subjective, so you can get away with pretty much anything if you defend your design choices well in your descriptive text. Aesthetics is also pretty subjective, which is why I recommended you jump way out on the design/styling limb. It may not be what the instructor personally likes, but if wild enough, they'll have to admit it's out of the box looks have merit. Craftsmanship is pretty easy to judge, so work clean and neat and you score well. Stick to the problems within the program and don't worry about anything else, letting the grade fall where it will.

 

The aesthetic flaw often associated with a flat and horizontal sheer is how it will appear in real life, taking on the appearance of a reverse sheer where it may not be wanted.

Found this brief discussion of sheer lines: http://www.goodoldboat.com/reader_services/articles/thingofbeauty.php

There are a few other articles at the site you may be interested in.

Just to have a lot of things to look at and consider, you may want to go to Google Books and look up The Rudder magazine. Annuals for most of the first two decades of the 20th are available for free in PDF form. You will find many lines studies reproduced therein and more than a few how to build articles covering all sorts of boats. This will give you a good reference for what has been done, and also for the form and dimensioning of sails.

Since you've expressed interest in multi hulls, I've referenced this in the past: http://www.catamaransite.com/catamaran_hull_dimensioning.html ; and http://www.catamaransite.com/catamaran_hull_design_formulas.html

Also, a number of the professionals who post here maintain their own websites and among those you'll find articles about any number of boat related things, including their own musings on projects they personally thought interesting, including less well known sail rigs like dynasails, aft-mast rigs and other things.

 

from PAR

Boats may be versatile, but I would say functionality remains objective, not subjective. That's why I would suggest the OP choose a craft where the functionality is both easily appreciated and well developed. And then leave those aspects alone and work around them. But as you noted, there is the inescapable need to game the teacher a little and make life easier on oneself. We have no way of knowing how teacher will judge function.

How about a steampunk tourboat for the Cape