# houle significative

## English translation: Significant wave height

 12:10 Oct 25, 2005
French to English translations [PRO]
Ships, Sailing, Maritime
 French term or phrase: houle significative Also referred to as "Hs". The context is as follows: "Pour l'application du présent paragraphe, les parties se réfèrent à la valeur de Hs par des fonds de trente mètres en face du brise-lames ..."
 Sarah RussellUnited Kingdom Local time: 23:06
 English translation:Significant wave height Explanation:Significant wave height, Hs, is approximately equal to the average of the highest one-third of the waves. Hs is calculated using: Hs = 4.0 * sqrt(m0) where m0 is the variance of the wave displacement time series acquired during the wave acquisition period. However, since wave displacement time series are not returned from NDBC's wave measurement systems, variance is calculated using the nondirectional wave spectrum according to the following relationship: m0 = sum(S(f)*df) where the summation of spectral density, S(f), is over all frequency bands, f, of the nondirectional wave spectrum and df is the bandwidth of each band. NDBC wave analysis systems typically sum over the range from 0.03 to 0.40 Hz with frequency bandwidths of 0.01 Hz. Some newer systems sum up to 0.485 Hz with bandwidths that vary from 0.005 Hz at low frequencies to 0.02 Hz at high frequencies. Dominant, or peak, wave period, Tp, is the period corresponding to the frequency band with the maximum value of spectral density in the nondirectional wave spectrum. It is the reciprocal of the peak frequency, fp: Tp = 1/fp Dominant period is representative of the higher waves encountered during the wave sampling period. Greater detail on the processing of NDBC wave data can be found here. NDBC also provides estimates of the height and period of wind-seas and swell on each station page. Values for these quantities are calculated by applying the above process to the respective wind-sea and swell portions of the wave spectrum. The algorithm used to estimate wave steepness is taken from work done by William Buckley, discussed in a paper that appeared in the Journal of Naval Engineers, September, 1988, titled " Extreme and Climatic Wave Spectra for Use in the Structural Design of Ships". The algorithm involves the relationship between significant wave height (Hs) and dominant wave period, or more precisely, its inverse, peak wave frequency (fp). The algorithm follows: val = exp(-3.3 * ln(fp)) if Hs > (1/250 * val) steepness = 'very steep'; elseif Hs > (1/500 * val) steepness = 'steep'; elseif Hs > (1/1000 * val) steepness = 'average'; else if Hswell >= Hwindwv steepness = 'swell'; else steepness = 'average'; --------------------------------------------------Note added at 16 mins (2005-10-25 12:26:47 GMT)--------------------------------------------------What is the importance of wave steepness and how is it calculated? The algorithm that we at GLive involves the relationship between significant wave height (Hs) and dominant wave period, or more precisely, its inverse, peak wave frequency (1/fp). Wave Length is the distance between successive wave crests. Wave period is the time it takes two crests to pass a fixed point (such as a reef). http://www.gowerlive.co.uk/wave steepness.htm
Selected response from:

Maria Luisa Duarte
Spain
Local time: 00:06
 Thanks very much for your thorough response4 KudoZ points were awarded for this answer

5 +2Significant wave height
 Maria Luisa Duarte
5 +1significant swell
 Jane Lamb-Ruiz (X)
4Hs (significative height)
 Nikki Scott-Despaigne

2 mins   confidence: peer agreement (net): +1
significant swell

Explanation:
rise and fall of the ocean...the swell

--------------------------------------------------
Note added at 6 mins (2005-10-25 12:16:16 GMT)
--------------------------------------------------

The first reference explains the term...it says severe here but if you go into the text, you will see they talk about significant swells as well

The port approach channels can be subject to severe swells which induce ...
throughout their turn into the harbour and so can experience significant rolling ...
www.omc-international.com/clients.htm - 25k - Cached - Similar pages

Common use Infrastucture
During periods of significant swells cargo can neither be loaded nor unloaded
... As a result of the swells, the port can be closed for periods ranging from ...
www.dotars.gov.au/terr/ChristmasIsland/cui_2.aspx - 30k - Cached - Similar pages

 Jane Lamb-Ruiz (X)Native speaker of: English, PortuguesePRO pts in category: 4

disagree  Tony M: Out at sea (50m depth), houle = waves in many ways. I think you'll find 'Hs' is the English abbreviation, they've used 'houle' just to make it fit the 'H', and in any case, 'vague' wouldn't work here either
 13 mins
-> Dusty how can houle mean anything other than swell?

agree  Tom Bishop: Hs can be employed re a number of parameters, incl. wave height, swell and both combined. From my own experience listening to marine forecasts in French and in English in the Channel Islands/Brittany, houle significative = significant swell.
 1 hr
-> I think it's both..maybe wave height is better in the actual measurement.

agree  Graham macLachlan: This is a nautical text and as such "houle" most definitely means swell, ie long rolling waves that do not break// Maria's algorithm says as much where she has confused the hs of "height swell" with "houle significative"
 2 hrs
-> yes..a houle is a swell and not a wave..

neutral  Nikki Scott-Despaigne: Agree that "houle" is "swell", not the same as wave. However, I believe I have identified that the French conveniently but erroneously translates Hs as "houle significative" whereas orig. lang. sources suggest it is "signif. ht" in ref to waves. See below
 20 hrs

13 mins   confidence: peer agreement (net): +2
Significant wave height

Explanation:
Significant wave height, Hs, is approximately equal to the average of the highest one-third of the waves. Hs is calculated using:

Hs = 4.0 * sqrt(m0)

where m0 is the variance of the wave displacement time series acquired during the wave acquisition period. However, since wave displacement time series are not returned from NDBC's wave measurement systems, variance is calculated using the nondirectional wave spectrum according to the following relationship:

m0 = sum(S(f)*df)

where the summation of spectral density, S(f), is over all frequency bands, f, of the nondirectional wave spectrum and df is the bandwidth of each band. NDBC wave analysis systems typically sum over the range from 0.03 to 0.40 Hz with frequency bandwidths of 0.01 Hz. Some newer systems sum up to 0.485 Hz with bandwidths that vary from 0.005 Hz at low frequencies to 0.02 Hz at high frequencies.

Dominant, or peak, wave period, Tp, is the period corresponding to the frequency band with the maximum value of spectral density in the nondirectional wave spectrum. It is the reciprocal of the peak frequency, fp:

Tp = 1/fp

Dominant period is representative of the higher waves encountered during the wave sampling period. Greater detail on the processing of NDBC wave data can be found here.

NDBC also provides estimates of the height and period of wind-seas and swell on each station page. Values for these quantities are calculated by applying the above process to the respective wind-sea and swell portions of the wave spectrum.

The algorithm used to estimate wave steepness is taken from work done by William Buckley, discussed in a paper that appeared in the Journal of Naval Engineers, September, 1988, titled " Extreme and Climatic Wave Spectra for Use in the Structural Design of Ships". The algorithm involves the relationship between significant wave height (Hs) and dominant wave period, or more precisely, its inverse, peak wave frequency (fp).

The algorithm follows:

val = exp(-3.3 * ln(fp))
if Hs > (1/250 * val)
steepness = 'very steep';
elseif Hs > (1/500 * val)
steepness = 'steep';
elseif Hs > (1/1000 * val)
steepness = 'average';
else
if Hswell >= Hwindwv
steepness = 'swell';
else
steepness = 'average';

--------------------------------------------------
Note added at 16 mins (2005-10-25 12:26:47 GMT)
--------------------------------------------------

What is the importance of wave steepness and how is it calculated?
The algorithm that we at GLive involves the relationship between significant wave height (Hs) and dominant wave period, or more precisely, its inverse, peak wave frequency (1/fp).
Wave Length is the distance between successive wave crests.
Wave period is the time it takes two crests to pass a fixed point (such as a reef).

http://www.gowerlive.co.uk/wave steepness.htm

Reference: http://www.ndbc.noaa.gov/wavecalc.shtml
 Maria Luisa DuarteSpainLocal time: 00:06Native speaker of: English, PortuguesePRO pts in category: 12
 Thanks very much for your thorough response

agree
 1 min
-> Thank you Dusty! MLD

disagree  Tom Bishop: Hs can be employed re a number of parameters, incl. wave height, swell and both combined http://www.ndbc.noaa.gov/windsea.shtml From experience of marine forecasts in French and English in Channel Is./Brittany, houle significative = significant swell.
 55 mins
-> A Day in the Life of a Translator! have a nice evening Tom!MLD

agree  Bourth (X): Indeed. Theoretically it is "swell", but more often than not it simply refers to waves.//Esp since an Ifremer site defines Hs as "hauteur signficative de la vague"
 7 hrs
-> Thanks! MLD

agree  Nikki Scott-Despaigne: See my findings below. I consider French conveniently but erroneously takes Hs as "houle" and agree that it is in fact for waves... Agree of course that "houle" does mean "swell" ...
 20 hrs

20 hrs   confidence:
Hs (hauteur significative)
Hs (significative height)

Explanation:
http://www.proz.com/kudoz/1167732

“Hs” is a recognised term.
The original French erroneously describes this as “houle significative”.
Of course, “houle” is classically translated as “swell”.
However, it is essential to account for the initial error in the French text you are working from.

Look at Figure 2 here : http://www.ndbc.noaa.gov/windsea.shtml

“Hs” is used to refer to height for sea and swell significant wave height.
I read this to mean that “Hs” is short for “significant height” in such contexts, be it specifically for waves or for swell.

Other sources corroborate this : cdip.ucsd.edu/?nav=documents& sub=faq&xitem=nowcast&xdoc=rec-nowcast

Several sources would appear to concur that “Hs” is commonly used for “the average height of the highest one third of a wave spectrum” and that they are indeed referring essentially to the height of the waves.
Sticking my neck out, I conclude that the French original is wrong is opting for a convenient “houle significative”. We all seem to agree that
- wave and swell are not the same
- Hs is originally an English language term used to describe wave height (for which there is a widely recognised definition.

1 - http://www.ndbc.noaa.gov/windsea.shtml

“Figure 2. Comparison of NDBC's modified steepness method with the estimates from the Navy's wave model: a) combined wind-seas and swell significant wave height (Hs), b) swell Hs, and c) wind-seas Hs.”

2 - cdip.ucsd.edu/?nav=documents& sub=faq&xitem=nowcast&xdoc=rec-nowcast

“significant wave height of swell”

3 - http://www.meteomer.fr/scatt_ex.htm

4 - www.mxak.org/weather/waves.pdf

5 - www.soc.soton.ac.uk/JRD/MET/ WGASF/CATALOG/soc_waveht/soc_waveht.html

 Nikki Scott-DespaigneLocal time: 00:06Specializes in fieldNative speaker of: EnglishPRO pts in category: 186

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