AC 36 Foiling Monohulls

[Dolfiman]

To illustrate what looks like Imoca 60 races in small format/ coastal conditions (inc. runs against chrono, race round Île de Groix and a 24h / 250 NM race with a night) these videos of the 2016 Défi Azimut offshore Lorient, it was the last contest / warm-up before the Vendée Globle itself:
Défi AzimutDéfi AZIMUT IMOCA 2017 https://www.defi-azimut.net/?mode=archives-videos-2016

Also the teaser of the next one (23-25 sept. 2017) :
Défi AzimutDéfi AZIMUT IMOCA 2017 https://www.defi-azimut.net/?mode=medias_videos

What could be very interesting is the planned conference on "Spolights on innovation" next Friday 22 sept (my translation here below) :
"As it is the tradition for seven editions, the Azimut Challenge will start on Friday 22 sept. morning (9:30) with a round table organized by the Eurolarge Innovation business cluster. At the Cité de la Voile-Éric Tabarly, naval architects, engineers and experts will detail and explain the new technologies at work and the on-going developments aboard the IMOCA 60. A great way to launch, with main actors of the offshore races, this sporting weekend sporting, convivial and rich of teachings on these high-tech sailing boats, that many teams design, build and prepare in Lorient or its surroundings, in the heart of the Sailing Valley."
No info yet available on the participants to this conf.

>>> Participants and topics now available and registration is open for those who can come (web site Défi Azimut) :
• Quentin Lucet, architect - VPLP Design, will present the projects of the firm which has designed the next monohull Charal for Jérémie Beyou (who was 3rd at the last Vendée Globe)
. Hervé Penfornis, engineer and close collaborator of naval architect Guillaume Verdier, will talk about the latest technological developments, Volvo 60, directly inspired by the Imoca.
• Anne-Claire Le Berre, research group of the Initiatives-Cœur team, will explain how to develop and optimize an IMOCA of a previous generation.
• Antoine Mermod, President of the IMOCA will come to decode the changes of the new IMOCA rules and how the class can evolve technically.
• Matthieu Robert, co-founder of MADINTEC, specialist in electronic and computer developments for racing sailboats, will present the latest innovations in this field.

 

[Tink proasail]

Tink - I agree, but one has to born to the game of test cricket. So many now days are looking for an instant buzz. However, the traditional approach depends so much on sound knowledgeable commentary, backed up with computer graphics, for it to become entertaining on TV.

Make it fast a fun by changing the format. In the racing my daughter was doing it was one lap of a short course, each race about 6 minutes 21 kids sailed a total of 60 odd races in 6 hours. I am sure there would be a great short format of races that could be real interesting. With modern graphics highlighting the right of way boat the racing could be accessible to all.

 

[sharpii2]

I envision something that looks like an IOR boat, with a diamond shaped deck plan, allowing a wide Beam and a very narrow WL.

Foiling boards, which are similar to those on the AC cats will be placed near the extreme Beam on Port and Starboard.

A relatively large crew, which serves as human ballast, will be on the windward side. They will have to quickly scramble when the boat changes tacks. They may be required to wear or carry water ballast packs as well, making this vessel a 21st century sandbagger.

I don't see a canting ballast keel as at all practical, as no engine to cant it will be allowed. Having the crew do it will simply take too long to win in a decent tacking duel. The keel ballast is likely to be token at best, to insure the boat does not list severely or capsize while at rest.

They will probably be no faster than the smaller "open whatever" boats, but will be able to change tacks much quicker.

 

[myszek]

I did a thread in the "Sailboats" forum here that was a detailed analysis of a 60' Moth using a bi-foil arrangement, sliding athwartship moving ballast and a 90 degree canting keel*.

Just a rough idea: canting foil may be easier to tack than canting keel. Something like this:

Of course, ballast should be placed on a separate keel fin.
regards

krzys

 

[schakel]

I envision something that looks like an IOR boat, with a diamond shaped deck plan, allowing a wide Beam and a very narrow WL.

Foiling boards, which are similar to those on the AC cats will be placed near the extreme Beam on Port and Starboard.

A relatively large crew, which serves as human ballast, will be on the windward side. They will have to quickly scramble when the boat changes tacks. They may be required to wear or carry water ballast packs as well, making this vessel a 21st century sandbagger.

I don't see a canting ballast keel as at all practical, as no engine to cant it will be allowed. Having the crew do it will simply take too long to win in a decent tacking duel. The keel ballast is likely to be token at best, to insure the boat does not list severely or capsize while at rest.

They will probably be no faster than the smaller "open whatever" boats, but will be able to change tacks much quicker.

I do not agree with you on that one. Just as in the last cup they will be able to store power in batteries is my first guess.
This energy can be used for the canting keel.

 

[tspeer]

I do not agree with you on that one. Just as in the last cup they will be able to store power in batteries is my first guess.
This energy can be used for the canting keel.

I would really hate to see the AC go the powered route. They used powered controls in AC33, but that was an anomaly due to the defender throwing out the racing rules regarding stored energy. USA17 was sailed with all manual power and could have raced that way had the defender not gone the powered route. The accumulators used in the AC50s were a necessary safety item to have a rational hydraulic system design, after the AC72 Design Rule took the stored energy restriction way too literally.

Batteries have an issue in that they can't start off totally discharged. The only way to keep a lid on the stored energy would be to specify a maximum battery capacity and allow the boat to start with that capacity fully charged.

 

[tspeer]

I think there's a fundamental problem with foiling monohulls in close quarters match racing. In order to foil, you need to have a light weight boat, powered up. To get power, you need beam to generate righting moment. A multihull provides the righting moment within the max beam of the hull(s). Most (the Moth being the rare exception) existing foiling monohulls allow the foils to extend outboard of the beam of the hull. This is manifestly unsafe for match racing - think Ben-Hur style chariots.

One way around this problem might be to ensure the foils stay within the max beam of the hulls, and give the monohull the beam of a multihull. This could mean a cross between Mark Pivac's Moth design that Brett Burvile sailed in the Perth Moth World's in 2000, and the KZ1 big boat from the 27th AC in 1988.

The Pivac/Burvile Moth configuration was later ruled to be a multihull because the foils gave it two laterally separated waterplanes. There would need to be suitable definitions of "monohull" and "appendage" in the design rule for a foiling, match racing monohull.

The scows had a similar issue with tunnel hulls.

As you stretch the beam and allow foils, at what point does it cease to be a monohull and become a catamaran?

 

[Dolfiman]

As you stretch the beam and allow foils, at what point does it cease to be a monohull and become a catamaran?[/QUOTE]

You are right, IMOCA class also faced this issue and adopted this monohull definition :
"Monohull: A “monohull” such as that understood in the present rules is defined as a boat:
- with a single flotation plane at rest or under sail in normal sailing trim.
- of which hull depth in all transverse sections shall not decrease towards the centreline of the boat.
For this definition, the hull does not include its appendages (Article C.7 and Section E)."

Imoca class rules 2017. : https://www.imoca.org/modules/kameleon/getFile.asp?id=687&name=classrulesimoca2017v11.pdf

 

[CT249]

The IMOCA rule has been pretty commonly used since the first effort to outlaw a Dominion type said something like "the bilges shall be no deeper than the keel". That produced what was essentially a trimaran version of Dominion among the entries for the Quincy Cup in around 1899, so after that the "no decrease" rule was generally adopted.

Tom, it's interesting that you disagree with stored power. So do I, but would you mind outlining your reasons?

 

[Konstanty]

The IMOCA rule has been pretty commonly used since the first effort to outlaw a Dominion type said something like "the bilges shall be no deeper than the keel". That produced what was essentially a trimaran version of Dominion among the entries for the Quincy Cup in around 1899, so after that the "no decrease" rule was generally adopted.

Tom, it's interesting that you disagree with stored power. So do I, but would you mind outlining your reasons?

The energy accumulator can come from wind or water turbines This energy can be accumulated during sailing before the start.

 

[CT249]

But that's arguably not sailing as we know it, which is using sails rather than turbines.

That doesn't mean that turbines are bad; it's just that they are so different they are not part of the sport we play in the AC. It's the same as the fact that snooker is not bad, but you don't play snooker in the world billiards championships. Rugby is not bad, but you don't enter the soccer football world cup and start holding onto the ball and running with it.

 

[Doug Lord]

Worlds first fully foiling (upwind and downwind) keelboat. Light air takeoff in about 5 knots of wind. Upwind foiling in 7-8 knots wind.
RM is key to any foiler............
--On an AC boat the racks could stick out a bit further than the "Q" foils probably eliminating hull to foil contact between raceboats while still allowing the Welbourn Q foils to work.


picture and details from Michi and Hugh Welbourn:

 

[schakel]

I would really hate to see the AC go the powered route. They used powered controls in AC33, but that was an anomaly due to the defender throwing out the racing rules regarding stored energy. USA17 was sailed with all manual power and could have raced that way had the defender not gone the powered route. The accumulators used in the AC50s were a necessary safety item to have a rational hydraulic system design, after the AC72 Design Rule took the stored energy restriction way too literally.

Batteries have an issue in that they can't start off totally discharged. The only way to keep a lid on the stored energy would be to specify a maximum battery capacity and allow the boat to start with that capacity fully charged.

For research reasons: Light batteries will be extremely usefull to develop.
Can be used in hybrid cars, Boats, planes and so on.
Always thought one of the reasons for the cup is to be a research platform.

 

[Konstanty]

But that's arguably not sailing as we know it, which is using sails rather than turbines.

That doesn't mean that turbines are bad; it's just that they are so different they are not part of the sport we play in the AC. It's the same as the fact that snooker is not bad, but you don't play snooker in the world billiards championships. Rugby is not bad, but you don't enter the soccer football world cup and start holding onto the ball and running with it.

A small wind turbine or water turbine to charge an electric or mechanical acumulator is nothing new on sailing yachts.

 

[OzFred]

For research reasons: Light batteries will be extremely usefull to develop.
Can be used in hybrid cars, Boats, planes and so on.
Always thought one of the reasons for the cup is to be a research platform.
View attachment 135841

I think the 80 million automobiles sold each year that can all potentially have electric or hybrid engines are a hugely greater incentive to produce lightweight batteries than a quadrennial sailing competition with half a dozen (extraordinarily expensive) boats. ;-)