[Billy1119]

Wow, looking at some of the content in that link simply gives me a headache. I think it's a little out of my league, although I can't know for sure because I have no idea what it is.

[EnigmaNZ]

I skipped over the equations and jusr read the results, could that be cheating, anyway, it does also show that there is more to being a naval architect than coming up with nice designs, whew.

[AMG]

Not a Naval Architect, but I have been reading a lot of such research and often it ends like this one, "it is up to the captain".

What I am more interested in and also been through a lot without certain conclusions, is how to avoid producing wake? I could imagine a boat with little wake will also produce less motion that cause seasickness.

Where I live we need passenger ferries that are pretty fast, 20-30 knots, carrying 200-300 pax and still producing small and soft waves that don´t erode the islands and disturb small pleasure boats.

It should also go with a minimum draft and be able to go in with the bow to pick up passengers. They are landing every 5-10 minutes.

Hovercrafts would be perfect if they were not so noisy, but maybe a wavepiercer would work...?

[EnigmaNZ]

Over here in the Marlborough Sounds in New Zealand, it has been found that high speed ferries, the 98m Incat is used currently, produce shore damage from their wake to the extent they have had their speed cut to less than 18k in places. WP are not necessarily kind on the enviroment. The scientific reasoning is here

http://www.marlborough.govt.nz/conte...32Analysis.pdf

Sheese, Sweden is all little islands, didn't realise it was to that extent, I really must get out more, hehe. I would suggest swath but too much draft.

http://www.bullshooter.com/jmart/cloudx/

[AMG]

Thanks for this interesting link. I have been reading Danish and Norwegian studies on fast ferries, mainly catamarans, which are causing unexpected and severe erosion on beaches.

We have from this summer tried a small number of "low wash" zones instead of speed limits. The result is mainly that the ferries and larger yachts slow down when people are present to see them, but still create wake when nobody is around...

As I live at a narrow passage I can see the difference in wash from all kinds of boats and speeds, and I have observed what I call a "Tsunami effect". Certain boats, like a 35´Coast Guard speedboat we have, when going 30 knots or more, can produce really "strong" waves that hit hard and raise high, while other similar boats at that speed creates almost no wake. I guess it is the weight of the boat that matters, despite they seems to ride as any other speedboat.

Also the ferries are quite different from each other, some create wake that looks innocent but crashes hard to the shore, like tsunamis...

On SWATH, they have too much draft to be used here, but I guess they have the sweetest motion for the passengers.

[Innomare]

I once saw a huge 250 m tanker and a small 30 m patrol boat sailing one after the other on the canal coming from the port of Rotterdam. Both where going at the same speed (around 10 knots). The remarkable thing is: the 20.000 ton tanker had almost no stern wave, while the 100 ton patrol boat was creating a much larger stern wave (0.5-1 m).

The main reason is the immersed stern area. The tanker had no immersed stern area and the streamlines could follow the hull nicely all the way, while the patrol boat was a typical hard-chine hull sailing at the "hump speed" (just before planing, with lot's of trim). The low pressure "hole" dragging behind its stern created a large stern wave.
I wouldn't be surprised if the patrol boat was burning more fuel per nautical mile than the 200 times bigger tanker.

Bruno

Naval Architect

[Garry Hartshorn]

Low wash cat in service on Sydney Harbour

[tartanski]

Im surprised the BGV was not in here already or did I miss it?

Site is in French there is a buttin to Select english on the home page but I could not use it.
Check out the Technique page you will see some nice CATIA images for the functional steel design.

http://www.bgvinnovation.fr/index.htm

http://www.bgvinnovation.fr/megayacht130.htm

[catmando]

Originally Posted by tartanski

Im surprised the BGV was not in here already or did I miss it?

Site is in French there is a buttin to Select english on the home page but I could not use it.
Check out the Technique page you will see some nice CATIA images for the functional steel design.

http://www.bgvinnovation.fr/index.htm

http://www.bgvinnovation.fr/megayacht130.htm

What is the problem with those Frenchies??? If I click on the English flag it will not let me in the site. Only clicking the French flag will do that but the language is French which I can't read.

[K1W1]

Hi,

Catmando

Here it is in English.

http://www.bgvinnovation.fr/bgvanglais/concept.htm

[Ju52]

I will give you this link for other low wash developments.

http://www.alsphere.at

It's from Austria but in English.
The picture is from this web site ... and shows the low waves behind the boat at 18kn.

[MikeElliston]

some more wave-piercing multi-hulls,
Water Wizards, a 50 ft power cat designed by Tim Kernan of Kernan Yacht
Design (formerly Waterplane), used as a photography/filming platform for yacht races, very long distance capable, with barely any wake.
http://oceanfilmboat.com/

Tim is also working with the new "M-hulls" more information and images can be found at his website.
http://www.waterplane.com/

[tartanski]

Check this out,

http://www.gizmag.co.uk/go/6835/

Solution seem a bit complex but I'd love to experience the ride with thos big shock absorbers.

No photos actually fully in ground effect so I'm wondering if it just operated with ground effect assistance.

[KCook]

That brings back certain memories ....

http://www.aero-web.org/database/air...ge.htm?id=7406

[tartanski]

Originally Posted by KCook

That brings back certain memories ....

http://www.aero-web.org/database/air...ge.htm?id=7406

YES I knew I had seen something like that before, I think convair made a large twin turbine Sea plane, she was a beauty, if you can source any photos id apreciate it.