Good First Book

A good first book

Hi Dan.

I would suggest Cy Hamlin's The Preliminary Design of Boats And Ships because it spends most of its time with general design principles such as the more famous formulas and ratios and what they all mean (in layman's terms). That and his extensive discussion of the "design spiral" concept and his insistance that the entire preliminary design process (where almost all of the major design decisions are made) can be done without any drafting tools other than a good pencil, lots and lots of paper, good erasers and perhaps a good ruler as well as a decent calculater.
I love his contention that this should all be somewhat fun to do. He dosen't much get into structual calculations, but he does give you ways of estimating weight and cost. His main emphasis is avoiding being painted into a corner with bad design decisions made early on.

Good luck

Bob

 

Wow, I have found this site. It feels like I've found a place to scratch my terrible itch. I too am interested in the "first book". I would like my first book to tell me all about the forces and loads that act on a boat and how designs handle those forces. Where should I start reading? Derek

 

I posted to quickly in my exitement. I would like to narrow down my previous question to specific answers. For example: If I had a 500 horse power boat, 27 feet long, 8 foot beam, and hull shape "X" and if it was loaded with eight people and a keg of beer and it is moving across water at 35 knots and it hits a five foot wave. What happens to hull shape "X"? Is there a book to help solve that riddle?

 

Well if the hull is shaped like an X and unless the keg is empty, my guess is that it wold sink...
Besides what is the specific weight of beer and how large is the keg and how much does it weigh, and are u fat or skinny...
Oh and btw you need to know how the hull is built, where the frames/stringers are etc etc

The question you stated is not specific enough to be able to answer, and besides there are no shortcuts to understanding what happens in any one specific instance at sea. If you already have the boat, put on the PFD and see what happens jsut leave the keg on the shore to start with

Otherwise start reading from the beginning in the above mentioned books, and after a year or so of constant reading you might be able to "solve your riddle".

 

I'm sure that reading all those books will be of any help. To answer your question, you'll probably need to perform towing tank tests (or at least put your boat through some CFD software)

 

Well Erik G, I most certainly don't want a boat that is going to sink. Lets say the keg weighs 70 lbs. I weigh 215 lbs of solid muscle and just picked up seven members of the Swedish girls bikini team weighing an average of 125 lbs each. The constants are length, beam, displacement, speed and engine torque and our five foot wave. The hull is the varible. We can put frames/stringers ect ect wherever we want. What happens to hull "X" or hull "Y" or hull "Z"?
And yes there are short cuts to everything. I walking one right now. I make a living finding shortcuts. Some people call it efficiency. I am not going to be reading a years worth of books. I too busy building a boat and drinking from my keg.
So where do I begin to find the answer to my riddle?

 

Edit:well to add some...
>Soren
how would a towtank tell what's going to happen to a hull when slamming into 5 foot waves? Are there tanks with wave capabities?
CFD for sure but it seems like djswan wants a quick answer to a question that is not easily answered.

>djswan
I do hope that you wasnt offended by my remarks...
What is it that you are really trying to figure out? Will it slam? (quite possibly), will it stay in one piece (depends on two many factors to answer). Will it float? (it should if you lower your speed)
Reading the above mentioned books gives you the insights how to approach a problem like this on your own.

The shortcut? Possible solutions could be to employ a naval architect with CFD knowledge, or pitch it as an assignment to a naval arch student that is learning CFD. Otherwise you can get well informed guesses by any knowledgeble yacht designer, but all of them will need a lot more facts to tell you anything than what you stated in your posts.

Shortcuts in yacht design are hard to come by

 

To make it short: Yes.

 

I don't know if it's worthwhile taking this thread seriously, but...

Q. Will the books listed enable one to calculate exactly what the stresses are on a particular hull when it meets a particular wave at a particular speed, etc.

A. No. Studies to support that sort of calculation have been done. I've heard of perhaps 3 cases where a hull was extensively fitted out with stress guages, etc. There may have been 10 or 100 times as many cases that I have not heard of. Much of this information is held in confidence, e.g. by America's Cup designers and defense contractors. In any case, such information is of limited value to a designer who has the objective of a boat fit to meet a wide variety of conditions. Only a few designers have the "luxury" of designing to a narrow range of conditions. One example would be those AC boat designers, and the results are not encouraging. Perhaps as many as 5% of AC boats have had a catastrophic failure of one kind or another.

I believe that at least one of the instrumented boats was a sailboat in a more or less public experiment. If so, then the results may be helpful in creating a finite element model of the hull and the transfer of stress/energy/whatever though the structure. I would welcome any comment about how much designers use of finite element analysis or other computerized modeling techniques.

 

Hey maybe it IS a riddle?!

Then Slow down goddammit, the swedish bikinibabes won't tolerate jumping 5 foot waves at 35 knots. If you don't then they'll throw you overboard and drink up your beer. A better idea might be to drink up half the keg, jump overboard WItH the keg as a PFD and company before they throw you overboard.

 

No but after reading the books he'll realise that

 

Back to the books

Getting back to the books.... I have realized that what I originally proposed building was a small power catamaran (15'-20'). I have a couple books on the way (slowly), but I wonder if after gaining a working* understanding of the basics if I will have to gain a working understanding of catamarans. I imagine a lot happens in the space in the middle once the boat gets moving. Can any of you recommend some good reading on catamarans? (Maybe an article accesible online if no books are available.)

Thanks,

Dan


*By "working" I mean enough knowledge that I can BEGIN designing a small boat.

 

What the books don't have

Thanks for the info Seadrive. Sounds disappointing. I'm taking this thread seriously. No offense taken EricG. I'm just getting info. You should have a beer and do something relaxing, like boating. I will.
I didn't mean to ask an unanswerable question to the experts. I deal with wind loads, snow loads, live loads, dead loads and even engineer for catatrophic events like avalanches and earthquakes when I design a timberframe home. I have to take into account what species of wood I am designing with. They all have different design values. If I design a boat out of Sitka Spruce but get a good deal on White Oak, could I downsize my sizes? I can't imagine building a boat without knowing what in theory, happens to it under certain conditions. A boat is no different the any other structure under load. Something happens to it when it hits a wave or rides up on the beach to pick up the Swedish bikini team.
I spoke with a well known boat builder in my area. He told me they don't do any engineering on thier boats, they build from experience. What! Is this the standard? Mabey somebody needs to write another book.

 

Don't take this too seriously, but there is a grain of truth buried in it...

Quote: ...enough knowledge that I can BEGIN designing a small boat.

Anybody can design a boat. The tricky part is to design the boat with predictable characteristics of stability, power, looks, strength, etc. There's an awful lot of successful boats out there that were built "by guess and by God", but most of these are based on long experience with the type and slow evolution. To shorten this education and development process, we rely on science and engineering to fill in for what we lack in previous experience and test data to aid us in advancing the design of new boats. If we apply a modicum of science and engineering to proven materials, shapes and techniques we are able to design conservative new boats with confidence. If we want to prove all aspects of a new design with science and engineering, the process become highly technical and occasionally moves into the area of ground-breaking scientific research. There is an awful lot that we don't know about designing a boat; we just fudge those grey areas with deductions made from past successful practice.

Loading on planing hull bottoms is one of those grey areas. The closer you look, the more complicated it gets. So we mostly take the easy - but expensive - way out and build models to test in tanks, then derive impirical data from the results, apply it to the real boat prototype, and cross our fingers that we didn't screw up somewhere along the line.

Or, as is the case with lower budget vessels built by non-professionals in their back yards, ya build yer idea and then ya tests her, and if ya don't die it was a good test!!