Talk:Wave-making resistance

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This articles completely fails to address wave making resistance.

There is no discussion on the history (Kelvin, Taylor, Froude, etc.) and the note on "out running the bow wave" is rubbish! I apologize for the force of my comments but this article is tantamount to mis-leading the public. A re-write will follow in short order Jmvolc (talk) 00:56, 29 January 2008 (UTC)

Seriously, the metric unit should be up front and on the figure. Liberia and US, wake up.

Merger proposal

I propose that the article Hull speed be merged into this one, and that replaced by a redirect to here. The reasons for this include:

• The topic of the other article is really a definite subset of the topic of this one
• The other article is badly referenced and not particularly well written, even to explain its small topic, IMHO. This article is badly referenced too, but makes a better job of the explanation.
• This article is well illustrated with two good graphs.
• The other article has a big emphasis on Froude number, which is only mentioned once here. If anything there is particularly interesting or relevant, I'm sure it can be incorporated here easily.

Maybe what we need is a new section here called 'Hull speed' that makes the connection between the concepts explicit. Then we need to try to find some references for statements and equations used here. Thoughts and suggestions? --Nigelj (talk) 20:55, 17 September 2010 (UTC)

I disagree. As a first order aproximation, hull speed is useful for creating estimates and rough assessments. Myself and others reference it regularly. I know that it is not definitive physics but more empirical physics particular to watercraft. I would rather be conservative and leave the articles where they will not become obfuscated and eventually lost. Yes, I've read the discussion on Talk:Hull speed -- Slamlander (talk) 19:37, 30 June 2011 (UTC)

I also dissagee strongly! DO NOT merge the hull speed article! People looking for the words "hull speed" are not likely looking for the teckno jargon the fellow above is talking about. I sure wasnt. The extra nonsense only confuses the issue of hull speed, no matter how so called "out of date" the term is. Many of us are very much still using terms like "hull speed", and "larboard" and "starboard" instead of "port" and "starboard". Many wooden sailing ship folk prefer the older historically accurate terms. — Preceding unsigned comment added by Maruater (talk • contribs) 18:57, 3 September 2012 (UTC)

Units

Both graphs would be useful if units were provided.Artreve (talk) 15:20, 1 November 2011 (UTC)

Indeed, and the "speed–length ratio" has units too. It may be common practice to drop those units, but for the average reader it may be helpful to know it's in $kt\cdot ft^{-1/2}$.

Actually, those are really arcane units. I know knots are still quite common in a nautical context, so it may be best to add them also in $kt\cdot m^{-1/2}$ (knots and metric) and $m^{1/2}/s$ (SI). I consider adding them in the coming days. Changing the graphs may be easier for somebody who has the source of those graphs – and can also change them to vector format.

Wake up, you Americans and Liberians. My country has used metric for about two centuries now. PiusImpavidus (talk) 19:35, 12 September 2013 (UTC)

Need definitions of bow wave and stern wave

In the current version, the terms "bow wave" and "stern wave" are introduced without any explanation of what they refer to. These terms are critical to understanding the topic, but their definitions would surely be completely unknown to most readers. What makes the matter worse is that many readers will likely think they do understand them. Especially, most readers will assume that the bow crest, which is easily perceived and visible, is the same as the "bow wave". But there is no way to reconcile this conflation of "bow crest" and "bow wave" with the theory. On the contrary, the interference pattern of bow wave and stern wave does not occur exclusively at the location of the bow crest. To say, as is true, that the bow wave and stern wave interfere, one must regard both of them not as occurring in some restricted region of time or space, but as being infinite in both. Or. on some subset of time and space with some specified initial and boundary conditions.

I think that the introductory session needs to be rewritten by someone who understands the physics. (I do not, but my guess is that "bow wave" and "stern wave" are concepts involving superposition: that they are not so much real detectable objects but mathematical constructs, just like the components of a real wave in Fourier analysis; the actual wave (infinite in all four dimensions) is understood as the linear combination of two unreal (conceptual) objects: a bow wave which would actually exist if the vessel had a defined bow but extended infinitely aft for an infinite duration, plus a stern wave which would be a real four-dimensional wave if the vessel extended infinitely forward forever and terminated aft with the actual shape of the stern.)

Mark.camp (talk) 20:37, 16 July 2014 (UTC)

Reference needed

There is no reference given for this statement:

"Waves generated by a ship are affected by her geometry and speed, and most of the energy given by the ship for making waves is transferred to water through the bow and stern parts.

Could a reference please be given by the author?

The statement is not only unreferenced, but it is not at all clear to me as a reader. In particular, I don't know what is meant by, for example, "stern parts". I'm sure that an area of the hull just below the water and near the stern must be one of the "stern parts", but I don't know what it means that this area is "giving energy for making waves". Intuitively, I assume that this area is consuming energy, not giving it, since the force on it is partly in the direction of motion. I think that this is what Newton's laws say.

Mark.camp (talk) 22:49, 30 November 2014 (UTC)

unclear term length

It might be beneficial to change length in the equation 4/3*sqrt(length) to water line especially when talking about sailboats. There is often a pretty substantial difference between water line and deck length so I personally believe that it be possibly misleading some that don't understand the difference of the two. Many modern race boats have almost plumb bow's with fine entries where the difference between waterline and overall length is minimized which gives them the benefit of being faster by increased water line length among other things. — Preceding unsigned comment added by 130.85.250.102 (talk) 16:26, 20 October 2016 (UTC)