AC 36 Foiling Monohulls

Very well done ,Alexander! Unfortunately, I think "the powers that be" would consider your boat a multihull because of the small buoyancy pods. Your idea on the rule is interesting-if there is no leeway in the new rule it will be very disappointing. I have the feeling that the renders we have seen may be translated into a one-design concept so that the Teams will have no choice but to do their boats like the renders.

 

An interesting idea. There are any number of alternatives to the AC75 that are "better" when judged by particular criteria. However, the class is what it is (for the time being), so anything that doesn't meet the class rules is somewhat irrelevant in terms of AC 36.

 

Alexander, any float/pod/cylinder/pipe or tube spread apart from central hull, no matter how low in volume, still makes it a multihull.
I've always thought the Australian/New Zealand Flying 18s with their cunningly designed racks are really trimarans. Suggesting this brings forth vomit from some believers? True, it is pedantic ... but maybe still the truth.
Interesting that you prefer the canard setup; they are a very rare species now.

 

Gary, OzFred and Doug, I am aware that the AC-organizers will hold next AC in the kind of boats they presented. But as you can make a foiling boat so much simpler and more efficient, I had to say something. I also sent my short paper to ETNZ.
The boat I suggested will be considered as a multihull, yes. Multihulls provide the best platform for this kind of foiling boat. You have the stability at low speed before you can stabilise with the foils, and you can minimise the hull drag, so you reach the take-off speed without so much wind. Look at the AC-50 catamarans!

When you write a "box-rule" it would be more relevant to specify what you want to obtain, instead of stating that the boat shall have a certain amount of hulls. Reasonable requirements may be: That the boat shall be able to moor outdoors, the crew shall be able to right it after a capsize, and you may also limit the size (not weight). You may also have requirements for safety, so e.g. the crew shall survive a pitch-poole at top speed (if you can not test that on the water, you can do simulations of the most probable crash-scenarios).

The reason for canard-configuration is that it is quite easy to obtain a stable altitude with a surface-sensor on the front foil. I have used both aeroplane and canard configurations on engine-powered and human-powered (Trampofoil) hydrofoils. My experience is that the canard keeps the altitude much easier. I think the reason for the aeroplane-configuration's popularity may be historical: With a configuration like Hobie Trifoiler or Windrider Rave, where you have both the windward and leeward foils in water, you only need altitude-regulation on the 2 front foils for the aeroplane-configuration, while a canard-configuration would require altitude-regulation on all 3 foils.

 

I think it is a shame that Alexanders buoyancy pods or the ones I show on NZAC will be judged by "the powers that be" as automatically creating a multihull from what in many other respects is a monohull.
Especially when you consider that the fastest monofoiler in the world uses 1 cu' buoyancy pods under the racks on each side! Nobody(in their right mind) would call the Moth a multihull-its not that slow!

 

Moths are a completely different story, their buoyancy bags are just to help with launching and retrieval. They're actually a hindrance when sailing as they don't offer any useful stability, don't prevent capsizes and create aero drag.

There are a good number of Moths that don't have any buoyancy in the wings. If it was banned, it would just make life a little harder when righting the boat, nothing more.

 

I don't think so-at least on NZAC the only purpose for the buoyancy pods is to make it a little easier to right the boat. They are not designed to be sailed on and I don't think Alexanders are either.

 

The rule writers aren't idiots, nor are they ignorant. The problem with specifying what you want is that it's basically impossible.

What, for example, does "moor outdoors" mean? How you define "outdoors"? IS it "outdoors" if the boat is mowed 100mm to leeward of a 50ft wide, 100ft high powerboat owned by the syndicate? Is it "outdoors" if it's moored in a tiny creek or 2km up a canal? What happens when a heavy gale or cyclone is forecast, as almost happened around the time of the Bermuda AC - if a crew moves their boat ashore (as they would have done with an AC72 or IACC boat) are they then banned because the boat is no longer defined as "moors outdoors"? Who gets to choose where each boat is moored, when conditions could mean that one mooring area is more exposed than the others?

It is "mooring outdoors" if you put pods under the wings? If you do allow pods then what happens when someone makes a boat that would fall over instantly if it didn't have 100ft self-powered pods with big cranes to hold the boat?

Similarly, how do you define "crew can recover from a capsize"? Do they get to capsize and recover in the best possible situation, even if that's completely unrealistic? Who defines the conditions in which the boat must recover?

 

Of course, you can not have a rule-text just stating: "boats shall be able to moor outdoors", that was what I wished as a purpose of such a rule. But I think the AC-organissers want to have boats, that you can moor, and take down the sails without having to put a 30 m long, quite delicate wing-sail in a hangar between the races. Maybe they come up with some clever rule to fix that. Let us hope the teams get the freedom to decide if they want to have traditional wing-masts with sails or the kind of double-luff sail we have seen in the renderings. The rule I sketched in the attachment to my first post was that the rig should have some limited projected area, say 500 sq. feet when you have hauled down the sail.
Having a rule about recovering from a capsize is not so strange. New Open-60 monohulls have to demonstrate that they can right the boat up from inverted position on the water. Something similar can certainly be applied also for AC-boats.

 

Thanks for the Moth-example Doug. Yes, the small floats I suggested will only be in water at such low speed, where you can not stabilise the boat with the foils. Maybe up to 8 knots boat-speed. From that speed up to take-off at some 20 knots the boat will work as a foil-stabilised monohull.
Another drawback with the AC-75 of nov.20 is that when you don't have such floats you have to get all the hydrostatic stability from the central hull, which cost so much friction-drag that you will need more wind for take-off.

 

In order for AC to influence the development of the sailpower technique, it must be necessary reefing and stand up independently after capsize. Otherwise it's all baloney - photomontage. In this forum I like that sometimes someone expresses their thoughts with the help of a drawing.

 

Okay, sorry, I thought you meant something novel about the way rules are drafted. Stating the purpose of a rule was quite common but is so often open to interpretation or being ignored that it seems to have largely dropped out of use.

 

Stars, Finns, Moths, C Class cats and other craft never reefed and they influenced the development of sailpower.

 

Yachts with such a history and such dimensions as AC should have such ambitions.

 

Perhaps, but history shows us that "influencing the development of the sailpower technique" can be done without reefing.

Yes, it would be good to have the AC sailed in ocean-worthy craft as the donors intended, but arguably that's a separate issue.