the resistance of tall ships

[liviper]

Is there any one knows how to caculate the resistance of tall ships,mainly Rsistance due to Heel and Induced Resistance.Can them be ignored?

[PAR]

Look Liviper, there's no easy way, nor cheap way around the answers you seek.

Education is what you need. You could attempt this on your own with personal study and building a library of related titles, or you can pay for the education through a correspondence course, assuming your country will permit this level of internet activity without molestation.

[daiquiri]

I don't believe you can ignore them - quite the contrary, imho. I expect the induced resistance to be an important part of the total resistance, since the underwater hull is basically an extremely-low-aspect-ratio keel. As such it will have a high lee angle and a big vortex attached to the keel, which means - a big induced resistance.

But I don't know where you could find the experimental data for that kind of hulls...

[ancient kayaker]

The calculation would be simpler for yachts with high aspect-ratio keels using profiles for which lift and drag data is available or can be calculated and where the influence of the hull can be ignored for approximation purposes.

I'm don't know if any of the available software will provide resistance under heeling and leeway conditions.

[liviper]

Originally Posted by daiquiri

I don't believe you can ignore them - quite the contrary, imho. I expect the induced resistance to be an important part of the total resistance, since the underwater hull is basically an extremely-low-aspect-ratio keel. As such it will have a high lee angle and a big vortex attached to the keel, which means - a big induced resistance.

But I don't know where you could find the experimental data for that kind of hulls...

What about the tall ships that don't have keels.Can the Rsistance due to Heel and Induced Resistance be ignored.

[liviper]

Originally Posted by ancient kayaker

The calculation would be simpler for yachts with high aspect-ratio keels using profiles for which lift and drag data is available or can be calculated and where the influence of the hull can be ignored for approximation purposes.

I'm don't know if any of the available software will provide resistance under heeling and leeway conditions.

I know that these resistance can be calculated for sailing yachts.But I don't know exactly how.DO you have this article 《predicting the speed of sailing yacht》.I can't download it from the website.

I also want to know how to caculate the resistance of tall ships that don't have keels.I mean large sailing ships.

[ancient kayaker]

Googling your question "predicting the speed of sailing yacht" found lots of references including this one: http://www.gidb.itu.edu.tr/staff/ins...ions/Cesme.PDF

There's a discussion thread in this forum at geometry of sailing

The topic is a complex one, especially for a classic tall ship, which is why I posted my comment on yachts as an attempt to simplify the subject. For a yacht with a fin keel it is probably fairly accurate to compute resistance separately for the hull, which can be obtained from software such as Free!Ship ignoring the effects of leeway heeling which are unlikely to be significant for a modern yacht hull, and the resistance of the keel which can be treated as a lifting foil using software such as JavaFoil: there is a discussion on this thread: Hydrofoil Profile Question

The keel behavior is affected by the presence of hull surface at one end and the effect of heeling on the performance of the keel would be significant, however a Google search should reveal useful references for allowing for these factors.

Although it might be relatively simple to get a reasonable approximation for a "modern" (last 100 years) yacht design with its separated keel and hull, for a tall ship with a long keel blended into the hull shape perhaps the only way to get all the factors taken into account would be to make a model and perform tank testing.

[daiquiri]

Originally Posted by liviper

What about the tall ships that don't have keels.Can the Rsistance due to Heel and Induced Resistance be ignored.

If you are talking about tall ships of traditional type, those that were in commercial and military service until the beginning of 20. century, they all had a keel.

[gonzo]

To start with, the term "tall ship" is a newly coined marketing gimmick. The hull resistance has nothing to do with the cosmetics of the rig or topsides. You can do the calculations as for any other hull,

[PAR]

Daiqiri, this poster appears interested in a free ride, both in a set of plans and explanations for all the design consideration involved in them. What they seem to want to avoid is the education necessary to understand these design considerations.

[liviper]

Originally Posted by PAR

Daiqiri, this poster appears interested in a free ride, both in a set of plans and explanations for all the design consideration involved in them. What they seem to want to avoid is the education necessary to understand these design considerations.

Ha,Ha.I don't know what to say.I do have some set of planes,and some methods to calculate the sailing yacht resistance, and I am major in ship design now.What i need is more information,because there are not any studies in this area.All my information is from google,AND for some reasons i can't open some usefull website.
And English is not my first language,maybe, I did not explain my idea very well.So please don't misunderstand me,I just ask for help,and I want to learn more about the sailing ship (sailing yatch ,tall ship , military training sailing ship).

[liviper]

Originally Posted by gonzo

To start with, the term "tall ship" is a newly coined marketing gimmick. The hull resistance has nothing to do with the cosmetics of the rig or topsides. You can do the calculations as for any other hull,

I searched this word from Wikipedia,what I rearly mean is learge sailing ships that don't have kells,like military training sailing ships.
The heel angle may change the wet surface,and the hull form underwater which can affect the frictional resistance.And the leeway angle make the ship like a hydrofoil with an attack angle in a flow which can bring Induced Rsistance,and also change the viscous pressure resistance.The total resistance is absolutely added,i just don't know the number,I mean how big it is ,relative to the total resistance that ignored the change.
I don't know if you can understande what i mean.
Thanks for your suggestions.

[liviper]

Originally Posted by ancient kayaker

Suggest we all stop posting on this thread, including the originator, and post any further inputs on the original thread per daiquiri's post.

Sometimes a website gets moved or is discontinued, but most of the ones listed by Google are valid as Google updates iself automatically at intervals. If you are having trouble opening certain sites you can include the link and we can at least advise you if there is a soultion to the problem.

There seems to be some information out there on this topic. The guys on the forum are a helpful bunch, I have benefited myself, but they do expect you to put in the effort to follow up the leads provided having been given a start.

You may never understand my situation.Some websites just are covered up,I mean i even can't search the link.
For instance ,I can donw load the article 《Predicting the Speed of Sailing Yachts》from the website http://www.oossanen.nl/download/peter.html ,but I can't open it ,it as damaged,and i can only download a few articles from that websit.I don't kwon if you have these problems.
I jusk ask for some articles on this subject to research.

[daiquiri]

Originally Posted by liviper

For instance ,I can donw load the article 《Predicting the Speed of Sailing Yachts》from the website http://www.oossanen.nl/download/peter.html ,but I can't open it ,it as damaged,and i can only download a few articles from that websit.I don't kwon if you have these problems.

I can confirm that the link above is broken. I also get the warning that the pdf file is damaged.

Originally Posted by liviper

I searched this word from Wikipedia,what I rearly mean is learge sailing ships that don't have kells,like military training sailing ships.

You are confusing the therm "keel" with the therm "fin keel". A keel was a fundamental structural feature for all wooden ships in service prior to, say, 1910's or 1920's of the 20th century. It was the "backbone" of any wooden ship (and it still is for boats constructed with some of traditional techniques)

And it also had the hydrodynamic function of providing the side force necessary to counter the lateral force from sails.
For example, this ship has a hull with a full-length keel which has both a structural and (together with the overall underwater hullform) hydrodynamic function:

So there is a keel, but it is very different from modern fin keels or centreboard keels, which you might have been referring to.

I suggest you to read this excellent article about keels written by Tad Brewer:
http://www.boatus.com/goodoldboat/keeldesign.asp

[liviper]

Originally Posted by daiquiri

If you are talking about tall ships of traditional type, those that were in commercial and military service until the beginning of 20. century, they all had a keel.