Good reasons NOT to design

two days agoI was test sailing a sailboat with new keel and ruder. Everything looked nice at the beggining, boat was very sencitive to ruder movements,quite fast as a cruiser. but then the wind built up it was imposible to sail, because of the weather helm. The "designers" job was awfull. We lovered the sails ,and started the engine. Soon I saw smoke, the engine was overheated. I raised the jib and tried to sail back to the marina. everything looked nice, until one gust the boat started turning, and we wereblown strait into one big ferry. Fortunately the engine started and we can sail away from that ship. This accident showed me how realy the designers job is.

 

This tread is out of hand. Here's the way I see it (as a enlightenable newcommer).

#1 There is only a minor a difference between designing a whole boat and making modifications to an existing boat. Yes, the anticipated mods need to be evaluated and if the mods are significant enough the evaluations might as well be for the entire boat, as the whole performance spectrum is dynamic and any one change effects the performance of every other part.

#2 Some like myself, see it as a means to possibly aquire something we might not other wise be able to afford. I am sure I'm not alone in this aspect.

#3 One of the problems is the repetitive questions. For example, I hit on the idea of modifying a monohull into a multi (as older monos can be bought relatively inexpensively), but until I thought about it more after the replies... I had not realized that there was a world of difference between the operating pardigms... the force dynamics and design needs are totally different. Once one thought about it more they became obvious.

And... evidently I was one of many that also thought about this idea breifly, with just enough time in between the last, that preliminary visual scanning of the treads did not show the previous. Thus the suggestion to address these common "ideas" in a read only thread... therefore potentially limiting the redundant questions and redundant answers... at least in part.

# 4. What happened to cause this thread to be started was a concern that too little info in the wrong hands often is inherently dangerous. This is true. And thus the comments that started this. As a professional in the field, he or she, would be prudent to wonder about it. Anywone with any degree of and sence of responsibility for their actions should be concerned.

#6, while it is possible to make mods or add features, one has to ask the question as to why it hadn't been incorporated by the original designer. For some things the reasons are based in engineering limitations and dynamics, others would be cost related for a production boat. Remember... the manufacturer had to sell the boat competitively and make a profit. There is a continuous trade-off here. Yes some mods may improve performance... but was not cost effective. If a mod/feature is in this realm there maybe an advantage to it DIYers... but how would you know which realm it was in?. Thus your back to re-evaluating all the parameters and adding additional mods to adapt the boat to new forces that would have been included had that particular mod/feature been incorporated from the beginning by the original designer. Sounds like a round robin to me.

Apparently, something similar to this is what was at the root of tamkvaitis's issue above.


So ok boys and girls... play nice.

 

Dem, well said!

Happened to be reading an Aussie magazine a couple of days ago called "Amateur Boatbuilder".
There was an interesting case study featured in an article about a nice skiff of 15ft. 6in. length with a 123 sq. ft. lug sail.
Quite a number had been built already and the handling and performance up until now had been exemplary.
One particular home builder who had purchased plans, sent an e-mail to the designer describing the launch day. He said that he had made one modification which was that the timber spars were substituted with heavy wall aluminium tubing.
Within minutes of launching a moderate gust had capsized the craft, and there was very considerable difficulty encountered to right the skiff.
The home builder questioned the designer as to the whether there might be some inherent flaw, that made the skiff so tender.
The designer responded saying that the additional weight of the substituted spars would be a hindrance as well as their lack of flexibility which would have negated the usual gust response of the sail.
However he said that even with that, the scenario still did not make sense, as the design was not for a sailboat that was even close to being overpowered.
In a follow up e-mail our intrepid home builder said something like the following: "I did not want to say so before, as I would be sure that you would not approve, but we shortened the hull by more than 2 feet. By we I refer to the boatbuilder who did most of the work and myself. The sail was made professionally by a qualified sailmaker as per your drawings. The reason for the change was to do with the size of the shed and availability of plywood".

The penny had finally dropped. The designer asked that an accurate sketch be sent to him for evaluation. On receipt of this it was apparent that the CE was now well behind the daggerboard and the skiff was around 50% overcanvassed, as it was now a considerably smaller boat. The boatbuilder had apparently not made objection to the changes in the design either.

The solution from the designer was a new sail of totally different dimensions to the original to suit the new hull design.
*********************************************************
It is a long story, sorry, but I didn't want to just summarize. To me it shows that in sailing craft one change affects almost everything else. It is a real shame that so much time, TLC and money can be lavished by a newbie designer on his own concept, done with only a smattering of understanding of all the forces involved in sailing.

 

How else is a new designer to substantiate his ideas, unless he builds?

Certainly one can find any number of sad and funny stories to illustrate the pitfalls of design without enough knowledge and experience. What about the gentleman who designed and built a sailboat for his retirement, a large flatbottomed unballasted affair? He acquired a telephone pole for a mast, and once the mast was stepped, the boat fell over and that was that.

But generally, if the beginner is advised to start small, little harm results, and much learning. The first boat I ever built, 30 years ago, was a scow taken from a Chappelle book. Gribble, as I called my overly-sturdy craft, was a disaster, with her home-sewed, too-small sails, but I don't think the experience did me any irreparable damage. It certainly taught me that I didn't know very much about the subject.

Those who put forward the idea that a little knowledge is a dangerous thing have evidently forgotten that even less knowledge is even more dangerous.

Besides, how exactly are we to discourage the ignorant from boat designing? Do we need a bureaucracy to decide who is fit to design and who is not? That seems a fairly horrible idea to me.

When folks appear here with what seems like truly goofy ideas, it takes relatively little effort to point them at a book or article that might educate them, if they actually want education. Or if it's a well-worn goofy idea, they can be directed to search the forum archives with even less effort.

Certainly, buying plans from a good designer will end up a much cheaper way to go than designing one's own boat, if one's time has any value at all. But for those who find the design process itself fascinating, that's beside the point.

Ray

 

Hi Ray, there is a good amount of truth in what you said. After all the forum is named " Boat-design.net". We dont expect to hear much from people just looking to buy a finished boat here. Starting small is essential in my book, and it is a lot more about the danger of starting big than the money wasted.
However now I want to qualify your remarks!

In my posting #48 the home builder made an executive decision to change the spar construction and the length of the hull after purchasing the plans.
He was clearly embarrassed to check it with the designer before going ahead. (Which was stupid)
Wouldn't he have learnt more quickly by getting on the phone before physically doing anything and asking the designer his opinion of the changes?
Not only would you have not wasted time and money, but he would have been given to understand some basic principles there and then.
Of course we can't and shouldn't try to regulate who can design or build, and the design process is fascinating, but to get any good at it you have to pay your dues first by spending time learning and observing, and then doing it and occasionally making mistakes.
Then it is not for everyone; some of us get reasonably good, while others remain fairly hopeless. I think it shows a lot of maturity if those in the latter category eventually recognize their shortcomings and decide to use better qualified help. :idea:

 

frosh, I agree that it makes no sense at all to buy a design and then modify it without consulting the designer.

You're right that there is a deep divide between those who might learn to be competent designers and those who have no hope. Unfortunately, the latter group can't really be told anything, and that's why they will never learn, either to design boats or to let someone competent help them.

There's an interesting story playing out in B.C. at the moment. A guy announced some time ago that he was going to sail around the world in an 8 foot boat, nonstop, via the Southern Ocean. Numerous folks tried to tell him that the project was possibly impractical, and his boat did not inspire confidence. For example, his rudder was fastened to the transom with steel door hinges. He was not receptive to criticism. Anyway, he hauled the boat from his home town in Washington to B.C., then launched and prepared to set out without any sea trials. Unfortunately, the boat started leaking immediately, and other unspecified problems have apparently convinced him to give up. He's broke and stranded. A kind soul has set up an online donation site to get him home, but it's a sad and goofy affair.

http://www.duckworksmagazine.com/06/outings/track/index.htm

Ray

 

Boats are an area that people, educated and uneducated alike, have mucked about with for hundreds of years for fun. What has changed?
We have forums like this so people who do dabble can do research.
The idea that getting an engineer to check your design means you lose ownership to it is WRONG WRONG WRONG. A good engineer will push you in the right direction without getting legally involved. A bad engineer will tell you your design is all bad an try to sell you his (people like that should be flogged in a public place).

 

AHahahahahahahaah....man did you see that thing???? I'm telling you that guy was trying suicide,how the hell in the whole world could exist a person so f...d up that he/she believes that it's really possible to safely sail that piece of crap...I wouldn't even sail it in a small lake, I'm sorry but this is not a metter of educated or uneducated...this is a metter of completly nuts and that's it :!:

 

You know, when I first read your post, I thought you were a seriously pompous *** for speaking so harshly about a vessel designed for an ocean voyage. Though being a newb to boat design, I have an appreciation for an ever-greater number of sailing/boating principles every day and it was inconceivable to me that a boat could be so bad that it was really worthy of such harsh negative comments on your part.

So finally, to put you in your place and let you know what an *** I thought you were, I decided to search around and find pictures of the boat so I could tell you what a pompous jerk you are...


And now that I have seen the boat with my own eyes, I can't help but say...


I agree with you, 100%

 

I do swear,I'm usually very respectful of other people's work...

 

This is actually quite an interesting thread. In my view, there exists a situation in which people EXPECT useful responses from experienced designers.

Just recently, someone asked for help to design a hydrofoil. No problem, until it dawned on me that he was actually asking me what the lift and drag on said foil was, and the takeoff speed of the boat etc. In short, given this planform, could you... to which my response was "search the forum and read a few books". Several students are also guilty of the same crime. NOBODY on this forum will do your homework for you.

That is how it should be. Many experienced members are here to advise, encourage and gently nudge newbies in the right direction. As for discussing the most recent projects, high-end CFD methods etc. Designers are employed because they CAN use and develop high-end methods. Strangely we have to make a living out of it.

In short, if someone wants to ask an in-depth question they can e-mail or leave a private message. But I'm not in the habit of answering either homework questions or ones that I know are dealt with on the forum.

So, newbies, please don't be offended by designers, builders and experienced boaters if we don't immediately tell you what you want to know. We're trying to get you to think through the design for yourself. The main purpose of the forum should be to ask for advice, opinions, and bounce ideas around. Also remember that there is always more than one solution to a problem.

Why shouldn't you design a boat? I Can't think of a good reason as long as you're sensible about it.

Cheers for now,

Tim B.

 

maybe sometimes we can be too quick to condemn newbie dream projects.

After all, if the builder of this little dream had found a motorhomedesign.net-
well, the world would be a little bit poorer...

 

I think your missing the point, its not his dream boat, he's not going cruising,he is challenging himself,-- forget the boat.

This man is going around the world with himself, I wouldnt want to do it, I cant stand myself that long. however it is a test of endurance.

The boat is probably quite safe ,uncomfortable but safe, all it has to do is float. I cant say I understand the man but he has my respect, utmost respect.

 

Ned kelly

Fantastic truck Hans, how about Ned on the marlin board/boarding platform, and its for sale if you look close- can't see the phone No. though, is this like,- your own counter culture creation? or ? More power to em' I reckon(gorgeous wife shaking her head at my enthusiasm), imagine all the fun to be had cruisin' the highways in that!Regards from Jeff.

 

Not mine. As the saga unfolded, he talked someone into hauling his boat north to BC. He put it in the water, for the first time, and prepared to set forth... but only for a few moments. Then the door hinges holding his rudder to the transom began to leak. Apparently he didn't even bed them.

He spent a few days at the dock, drying out his supplies and then Chuck Leinwebber, the kindhearted proprietor of Duckworks, started a fund to get him home. As far as anyone has heard, he never even put up the sails. Dockside observers say the boat appeared tippy even without the rig, and the designer was heard to mutter something about needing more ballast. Apparently enough money was donated to get him home.

I can't bring myself to respect a sailor of such supreme overconfidence that he wouldn't even bother to test-sail his boat before setting off around the world. Doesn't that seem like Job Number One?

Ray