|General: IHS Administration||Design of Foils: Foil-Struts-Controls-Performance||Design of Vessels: Hull-Machinery-Costs-Performance/Ops||History of Hydrofoils: People-Vessels-Operations||Hydrofoils: Commercial||Hydrofoils: Military|
|Hydrofoils: Models||Hydrofoils: Pleasure||Hydrofoils: Sailboats||R/D: Student Projects/Thesis etc.||Sources, Buy/Sell: Brokers-Builders-Designers-Operators||Miscellaneous:Hybrids-Other High Performance Vessels-etc.|
Updated last August 22, 2006
General: IHS Administration Top
We have made it easy and very inexpensive to join, or renew your membership, via a secure link to Pay Pal at our IHS home site as linked below for you to click on.
firstname.lastname@example.org, [Msgid=364642] *
[Date/Time=08-15-2003 - 11:55 AM] Name:Barney C Black email@example.com, [Msgid=488408]
[Date/Time=08-20-2003 - 8:51 PM] Name:Barney C Black firstname.lastname@example.org, [Msgid=491450]
This AMV CD-ROM # 2 has 61 documents with 8650 pages:
30 Documents on Hydrofoils.
11 Documents Applicable to Multiple AMV Types.
17 Documents on Air Cushion Vehicles (ACVs) and Surface Effect Ships (SESes).
3 Documents on Planing Hulls.
12 Rare Documents on Advanced Ship/Boat Design with Data.
Note: Priced at $12.00 for IHS members; $15.00 for nonmembers.
AMV CD-ROM #1, the first in this series, is still available.
IHS is making available this CD-ROM collection of technical documents on Advanced Marine Vehicles. These documents have been generally unavailable, as they were in private or government files and archives. It is the Second of a series planned to be produced.
IHS accepts payment by personal check, bank check, money order or cash.
We have also arranged for payment by credit card (online only!) at
The price includes postage, regardless of destination.
Orders must be pre-paid.
[Date/Time=08-21-2003 - 7:10 PM] Name:William White email@example.com, [Msgid=491987]
Cost of the dinner program is $25.00 per person. Menu: Rolls, Garden Salad, Marinated Chicken Breast, Green Beans, Rice Pilaf New York-Style Cheesecake, Iced Tea, Coffee.
The speaker will be LtCol Lawrence Ryder. LtCol Ryder will present an overview of High Speed Vessel (HSV) employment in Operation Iraqi Freedom and in Horn of Africa Operations. LtCol Ryder will discuss the growing importance of high speed craft in the implementation of Navy and Marine Corps transformation efforts. He will also provide an overview of the capabilities of the Navy and Marine Corps' newest ship, HSV 2 SWIFT, which was delivered 12 August 03. Finally, LtCol Ryder will provide an update on the Marine Corps' long-term goals for high speed craft.
As usual, the meeting schedule will be Social Hour/Cash Bar: 5:30 - 6:30pm; Dinner: 6:30 - 7:30pm; Program: 7:30 - 9:00pm. Make reservations no later than September 15 (Noon) if you plan to attend. Contact: Dave Kaysen: 301-775-2458, firstname.lastname@example.org; or Bill Hockberger: 301-699-5137, email@example.com
[Date/Time=08-26-2003 - 7:02 PM] Name:Barney C Black firstname.lastname@example.org, [Msgid=494668]
[Date/Time=08-31-2003 - 4:31 PM] Name:Mike K. ame2000, [Msgid=497703]
For those who were unable to come on Thursday the 18th, perhaps you can attend now that the date is moved to the 25th. If so, please make a reservation.
We hope that people who made a reservation for the 18th will still be able to come on the 25th, but we cannot assume this. It will be necessary for you to reconfirm (or cancel) your reservation for the new date by calling or emailing either Bill Hockberger (email@example.com, 301-699-5137) or Dave Kaysen (firstname.lastname@example.org, 301-775-2458).
For anyone who is inconvenienced, we regret the necessity for these last minute hurricane avoidance maneuvers.
[Date/Time=09-16-2003 - 8:50 PM] Name:Bill Hockberger email@example.com, [Msgid=508553]
[Date/Time=11-21-2003 - 10:20 PM] Name:Barney C Black firstname.lastname@example.org, [Msgid=548422]
The Center for Innovation in Ship Design was tasked by the Office of Naval Research and NAVSEA 05 to investigate the utility of seaplanes for supporting an offshore seabase. Our speakers will outline the history of seaplane development and operation and then present the main results of their study. They will discuss the potential uses and importance of seaplanes for future seabased military missions. They will also identify current technology boundaries and technical issues that need further investigation, including those related to integrating seaplanes into a seabasing environment. Finally, examples of potential design concepts will be shown.
For details, see the attached Adobe Acrobat file.
[Date/Time=11-21-2003 - 10:27 PM] Name:Barney C Black email@example.com, [Msgid=548428]
Attached File "troika~pdf.zip" - size 9192 Click Here To Download
[Date/Time=12-13-2003 - 2:29 PM] Name:Stephen Mc Donald firstname.lastname@example.org, [Msgid=558639]
[Date/Time=04-20-2004 - 12:28 PM] Name:Garry Fry email@example.com, [Msgid=633917]
If you look closely at the attached photo of Maya "The Beach" Bay you will see the RHS 70 hydrofoil at anchor in deeper water.
[Date/Time=04-20-2004 - 12:40 PM] Name:Garry Fry firstname.lastname@example.org, [Msgid=633923]
Image Attached: "MayaBayPhiPhiIslands.jpg" Click Here To View
I realise that the dB scale is not the same as for dB in air, but not how or why.
What I would like to know is; Is this a realistic figure? What kind of hydrofoil would this be for? Or is the wool being pulled over my eyes? Are the operators of the survey trying to convince us that the noise level is not significantly high?
By the way, there are dugongs in the area which are in danger of extinction and may be affected by loud noises.
For more info on the problem see
Thanks for your time.
[Date/Time=05-17-2004 - 9:42 AM] Name:Simon Varnam email@example.com, [Msgid=648647]
My familiarity with noise measurements is limited, however for airborne noise monitoring there are different scales that are used to account for different applications. Humans for example can tolerate noise pressure levels better at some frequencies than others. If I recall correctly, the dB(A) scale is often used when measuring the impact of noise on humans. This scale weights the noise level differently for each frequency component being measured before adding their effects together.
I would say that the same would apply for marine animals, namely that Dugongs could also handle noise levels better at some frequencies than others. Comparing the noise level measured for a hydrofoil (which could be expected to be fairly broad banded) against the output of a seismic system (which may be very narrow banded and in a frequency range harmful to the animal?) could therefore be problematical... regardless of how the dB measurements compare.
Good luck with you quest for a sound assessment of the risks in this case. By the way, you seem to have forgotten to include the website link you intended to provide.
[Date/Time=05-24-2004 - 10:26 AM] Name:Martin Grimm firstname.lastname@example.org, [Msgid=652999]
From http://www.fas.org/man/dod-101/sys/ship/acoustics.htm#conversion, I find the comparison from air to water is +62db for water. The example cited is a supertanker generating 190 dB is roughly equivalent to 127 dB in air. Ambient noise for the open ocean is 74-100 dB. A blue whale also generates 190 dB. They don't list what Dugongs emit.....
While the frequency would probably not necessarily be 'broadband', the likely source for a hydrofoil (alone) could be the turbulence in the boundary layer surrounding the foil, various turbulent eddies from vortices, cavitation, ventilated surface bubbles from surface piercing, etc. Weightings may be used (comparing sound levels to the sensitivity of the human ear)and included in the measurement, but any weighting scheme should be reported with the results. Also, the propulsion system (props, water jets, etc.) or support generator sets, etc. would be a major noise contributor.
The peak to peak amplitude of a time history of surface pressure can be estimated by 4 times the RMS (or also closely by Std Deviation) of the time history, then converted to Db by 20*Log10(P1/P2), P2 being the reference pressure which is 1MicroPa for water. We recently did some dynamic pressure measurements on the surface of a hydrofoil to measure transition of the boundary layer from laminar to turbulent, for which I have RMS values. A sample I looked at today measured 198 Db average (broadband) at 25 Knots on the foil surface itself. The number was similar for 15 Knots. The above web link relates transmission loss as the sum of spreading and absorption loss. The absorption loss is variable with frequency. Neglecting any absorption loss, 198 dB at the surface translates to 4.9 dB at 100 meters. With absorption included the number is smaller yet.
So, if the foil system is sub-cavitating and operating in a cavitation free operating envelope, my opinion is the foils themselves are highly unlikely to cause such a noise level alone.
[Date/Time=05-26-2004 - 3:37 PM] Name:Rick Loheed email@example.com, [Msgid=654516]
BTW Rick, my e-mail of thanks was returned. Maybe your mail box is full.
[Date/Time=06-02-2004 - 10:40 PM] Name:Simon Varnam firstname.lastname@example.org, [Msgid=658001]
For several years I have served as Editor of the IHS Newsletter and have struggled to obtain appropriate articles to place in the Newsletter each quarter of the year. Martin Grimm, our Sailor's page editor, has been a great help, not only for such articles, but others as well. Others of you have also contributed material from time to time, and this has been appreciated.
The purpose of this message is top solicit you greater support for interesting hydrofoil material -- particularly NEW and upcoming events and designs that are not published elsewhere (like FFI and Speed at Sea).
Therefore please send me such articles. A single to 1 1/2 pages including a picture or two would be great!! Of course there is no guarantee that your article will appear in the very next issue of the NL, but we will make every attempt to fit it in ASAP.
My best regards and thanks,
IHS Newsletter Editor
[Date/Time=07-12-2004 - 8:33 PM] Name:John Meyer email@example.com, [Msgid=678443]
[Date/Time=07-27-2004 - 11:14 AM] Name:Philip firstname.lastname@example.org, [Msgid=685371]
[Date/Time=08-19-2004 - 7:50 AM] Name:gene echols email@example.com, [Msgid=696531]
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