Scale models

[daiquiri]

Originally Posted by Matt.D

daiquiri , Thanks mate good to hear im not the only one who gets swamped!
U would be the man to ask what the fourmula for displacment is and also the one for calcuating hull speed?????? thanks Matt

I agree with Ilan Voyager's words. This issue of professional boat design vs. homemade design has already been a subject of many posts in the forum.
I personally was the one who wrote about the necessity for a designer to both study the theory and do a lots of practical sailing. And was labeled as "too negative" by some.

Matt, this forum is already full of almost all the info you might need, all you need is to use the "search" tool to your profit.

Here is one of (imho) the best-written posts on hull speed:
Hull speed
There is no "formula" for displacement. It depends on hull form and has to be calculated numericaly from hull's transverse sections. Here is Boatforum.net wiki page on displacement:
http://www.boatdesign.net/wiki/Displacement
And this page at Glen-L site explains you some basics about the argument:
http://www.glen-l.com/weblettr/weble...-designer.html
This is Ted Brewer's (he is a member of this forum, too) page with a primer on yacht design, which will explain you some very basics on parameters involved in boat design:
http://www.tedbrewer.com/yachtdesign.html

Don't expect to make a good hull form without studying and understanding the theoretical aspects of boat design. It could have been done back in 1700's and 1800's, when everything was there to be discovered, but not in our era of CAD and CFD systems and fuel crisis.

[FAST FRED]

I figure home designed does not pay.

Unless a boat is very unusual or radical , there should be a thousand choices of fine boats that are proven, over decades (or centuries) of real world use.

If the design is radical , only a big buck test tank will get those last few percent that was the reason for a radical design.

Most sailors are conservative because so few "great ideas!" have worked out in the sea, as well as they looked on paper.

FF

[Matt.D]

OK! i think of got it! dont be a fool! sounds like i could easily waste a lot of time and money and get nowhere fast! I think I will try and track down a set of plans for the desired shape I'm after. Thanks for all of your input. I'll post a thread for the plans I'm after shortly and hopefully someone will be able to help. Thanks again.
Matt D

[Ilan Voyager]

Have a nice day, Matt. We'll be waiting.

[MikeJohns]

Originally Posted by daiquiri

...........
I personally was the one who wrote about the necessity for a designer to both study the theory and do a lots of practical sailing. And was labeled as "too negative" by some. ..........

This is very good advice.
A problem that is often evident on these forums is a lack of real sailing experience.
There's nothing like experience to teach the necessities of design, it puts some reality behind the decisions of which compromises to adopt in a design relative to it's intended use.

cheers

[TeddyDiver]

Originally Posted by FAST FRED

I figure home designed does not pay.
If the design is radical , only a big buck test tank will get those last few percent that was the reason for a radical design.

Well, we got to remember those last few percent are crusial only for racers. Not so many home designers aim.. And those who do are ruled out to race agains other "home designs" etc..

[FAST FRED]

"I think I will try and track down a set of plans for the desired shape I'm after"

Perhaps it would first pay to make a list of your Desirements , in order of their importance to YOU.

Some desirements conflict,

A roomy fat boat is hard to get going fast.

A heavy load takes more sail, and handeling for light weather.

A fast skinny boat may lack load carry ability.

What trade offs are YOU willing to accept to get your "Dream Boat"?

Will help if you find a designer that has the same concerns as you.

FF



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[hoytedow]

Originally Posted by Matt.D

Thanks for the input guys . How much does a u.s penny weigh as they r a little hard to come accross over here in oz!

Matt.D

Matt.D, I am late coming to this thread, and did not see that anyone answered your question, so I went to the kitchen scale and weighed out 75 U.S. Cents(we call them pennies in casual speaking) and they weighed approx. 200 grams. Remember I used a kitchen scale so I don't trust it to be precise or very accurate.

[marshmat]

US pennies:
Pre-1982 are approx. 3.1 g each. (95% Cu, 5% Zn)
Post-1982 are approx. 2.5 g each. (2.4% Cu, 97.6% Zn)
Canadian pennies:
Post-2000 are approx. 2.35 g each. (94% steel, 1.5% Ni, 4.5% Cu). This is the 9th formula they've tried for them so far and they still cost more than a cent to make....