Formula for Mono-hull water line placement?

[Dockhead]

Originally Posted by GILow

Well, reading that sent my brain out my ears.

And I reckon you made half of those terms up!

Prismatic Coeficent! Ptooey.

I guess you're joking, but in case you weren't, Snowy knows what he's talking about.

Carlson Design – Hull Designer

https://sourceforge.net/projects/freeship/

[GILow]

Originally Posted by Dockhead

I guess you're joking, but in case you weren't, Snowy knows what he's talking about.



Carlson Design – Hull Designer



https://sourceforge.net/projects/freeship/

Sorry. Aussie humour. Does not always translate.

Yeah, that lad knows quite a bit about boats... for a Tasmanian.

[Cadence]

Originally Posted by GILow

Well, reading that sent my brain out my ears.

And I reckon you made half of those terms up!

Prismatic Coeficent! Ptooey.

There is a prismatic coefficient. It takes one hell of a lot of calculations if doing it by hand. Again not a job for a novice who is more likely to end up with a boat anchor than a boat.

[GILow]

Originally Posted by Cadence

There is a prismatic coefficient. It takes one hell of a lot of calculations if doing it by hand. Again not a job for a novice who is more likely to end up with a boat anchor than a boat.

Too right!

The way these computational tasks were done by hand astounds me. In my very early days of coding (pre Internet, so no Googling for an answer), I had to write a function that would perform Newtonian Convergence. (To calculate Annualised Rate of Return).

I had a small advantage, I am a Mathematician by training, but even so, just performing a few iterations of the process on a dataset with three transactions, to get my head around how I should code it, took me hours. (And I think I got the wrong answer anyway).

To think people used to manually run hundreds of iterations on datasets with dozens of transactions is astounding.

[TeddyDiver]

Originally Posted by MrSheep3

I am drawing up a rough sketch of a boat I would like to build, one day when I get the money, and I do not know of a better way to find how much lead to put in the keel for the most efficient waterline through the water without contacting an engineer. I have done some research on air buoyancy per cubic foot, 64 lb positive pounds and how much lead ways but I do not know the exact science behind it. If any one knows how to please help me!

Don't mind the negative comments. Make your sketches, buy a a couple of shelfs of boat design books, read them carefully, make more sketches, read them again a couple of times and have a decade for planning..

Been there done that Thou I had quite a bit of boat building experience before all that..

BR Teddy

[Zzmeyer]

Just wing it. What could possibly go wrong? Lots of useful information in Skene's Elements of Yacht design.

[james247]

Originally Posted by Zzmeyer

Just wing it. What could possibly go wrong? Lots of useful information in Skene's Elements of Yacht design.

Fundamentally what you are doing by trying to design a yacht of your dreams is healthy. You are learning the fundamentals of yacht design.
More importantly you are expressing what you want in a boat.
I suggest once you finish your design do as the old designers did and carve a half model. Or do as I did and build a radio controlled model. It teaches you so much about boats.
Once you have crystallised your thoughts you will find someone has designed what you are seeking. Because you have done the exercise of putting your thoughts on paper you will be a far more prudent purchaser and renovator of a yacht. You will know what you really want.
Many never realise what they want in their yacht. Your process of designing a yacht will give you the ability to recognise a great boat that will perform to the charastics you consider important.

[dcstrng]

Even for the hundreds of us who dream the dream, but will never design and/or build, learning the rudiments of boat/yacht design is invaluable. I think most of my generation started by laboring through Skene's and it is still a pretty good text because it doesn't assume the reader has anything much more sophisticated than a slide rule and a pencil -- and the laws of physics/fluid-aerodynamics haven't changed either... Fifty years later and dozens of "how to design" and "how to build books" in the library, not to mention a few sets of plans I purchased (pretty much to feed the dream, as it turned out) and a couple of years dabbling in the Westlawn course; it is clear I'll not ever build or design my own boat-- that much is for sure (and now I finally have the shop that could support it). By now I have pretty much all of the more popular (populist) design books, and a few apparently written for the naval architect who wants to try their hand in small boats (try Hammitt's "Technical Yacht Design" for a fun of wave theory, to bridge the gap...). Long-winded way of agreeing with those who caution about actually designing your own boat...

BUT, I do strongly encourage the study of the science/art... Regardless of your desired vessel, Glen-L, Bolger, Hunt, Bertram and Crowther and dozens of others have long since mastered anything the homebuilder is likely to ever require -- but learning their craft will make one a better-informed/better sailor. Can a backyard builder do it -- absolutely, of course... But there are vessels aplenty available for a song -- just begging for a willing owner to refurbish them... indeed, my generation cut is teeth on building from bare-hulls (a lost art, if it was an art) which allowed the money-strapped builder to have the product of a Hunt/Morgan/whatever on a budget -- but now days the same hull is almost as readily available, for fraction of what the hull used to cost -- as long as you catch it before the crusher crushes it. Still, the study of yacht design is well worth it, as a discipline in itself -- just don't get caught up in the quagmire of the virtual world, if the goal is to enjoy the real one.

[Don C L]

BTW my own boat was designed originally by Sparkman and Stephens to have 3120# of ballast. Then the builder after a couple years added 1000#! I guess they had complaints about the tenderness or wanted the boat to perform better to windward, still not sure. So even the masters may not get it perfect for everyone all the time.