Have You Foiled ?

[a64pilot]

There is no free lunch.

Let me explain that a little, I think current foiling boats are successful to a very great extent to their extremely light weight, it takes HP to push a hull through the water and it takes a lot of HP to completely lift it out of the water, the heavier you are, the more HP.
that dinghy in the video, I think I remember them saying in the video they used graphene, which I am completely not familiar with, but bet its extremely light and worth it weight in gold?
We disparage the average cruising Cat calling them CondoCats because they are loaded down with the necessities and some luxuries for cruising.
Well spend an enormous amount of money building an incredibly strong yet ultra light Cat for foiling, and then start loading it down with have to haves, and nice to haves for cruising, and what do you have?

Now I know someone that travels in an aerobatic airplane, he carries a shaving kit bag with him and has everything else overnighted to the next Motel, I guess you could do that

[a64pilot]

Does anyone know someone who is actually cruising a Gunboat? I think there may be a comparison there with a possible future foiling cruiser

[Stumble]

So there are two things that need to be understood to discuss foiling, and foil assist (lifting but not full foiling).

First foiling isn't free. Not interms of money, but in terms of drag. The foils themselves generate massive amounts of drag compared to non-lifting foils. So at any given speed on any given boat they generate X drag from the foils, and reduce drag by Y by reducing the wetted surface. It is only worthwhile deploying the foils when X<Y, this is called the cross over speed.

For the big maxi Tri's the crossover speed for their foils is about 22kn. Below that boat speed they keep the foils out of the water. For the VOR's with the mustaches I think their crossover is around 10kn upwind and 15kn downwind. For A-Class catamarans the foiling boats are still slower around the course in less than 6kn of breeze than strait board boats.

In order to get the foils to work for you, you need to be going fast, much faster than most cruising boats are capable of right now. Since there hasn't been a huge market swap to boats like the Pogo, and RM, to think everyone is going to just skip that step and move to foilers... highly unlikely.

Moving to aluminium foils instead of Carbon actually makes this worse. Sure you won't have the money invested in foils that carbon demands, but because carbon is so much stiffer than aluminium in order to carry the loads you need larger aluminium sections. This generates even more drag, meaning you have to be going even faster to get meaningful lift.

It's a negative spiral, the heavier the boat the more loaded the foils, the thicker they need to be. Which generates higher drag, which requires more structure, which makes the boat heavier.... If you want to foil you have to keep things light, it is critically important, it isn't just a nice thing to have, to get up on foils you need an incredibly stiff structure to keep the foils from deflecting, to do that you pretty much have to use carbon to keep weight down, this generates massive costs.


Second is financial costs. The daggerboards for an AC-45 cost roughly $500,000 each. Not a set, per foil. Including the rudders the AC-45's have something like $1.2 million of foils I need the water. The foiling Gunboats (40') and DNA (46') are roughly in the same place I think the DNA foil set runs about $800,000.

Even a small boat like the Moth's foils are in the $10,000 range for a set. These things are not cheap. I haven't seen any prices for the foils on the VOR's but mid six figures to a million dollars each would be my guess. And these aren't development costs, they are production costs. In order to keep drag down you need really thin foils, to accomplish that you need really high modulus carbon, and of course it's all prepeg autoclaves production.

Prices may fall a little over time, but I doubt it will be much, and certainly not for a long time. Most foils are using ultra-high modulus carbon, so boat builders are now compeating with sattelite and DOD manufacturers for this very limited resource, I just don't see prices falling any time soon.


If you want to foil there are some very approachable options like the Wazp (detuned Moth for about $13,000), or some foiling beach cats like the Whisper ($25,000), that are reasonably approachable. They Wazp particularly is designed to be easy to fly, not as fast as the Moth, and not trying to be. But worlds easier to sail.

[Dave22q]

Not being a marine engineer I have to rely on basic principles. Seems to me that lifting a hull by using foils makes a mono-hull more tender just as cutting off some keel would. it just seems dangerous to me- the combination of high speed and less resistance to a roll or pitch pole.

[foufou]

Not only have foilers been around since 1870 when Alexander Graham Bell succeeded but also the US navy tested one in 1945. David Kieper buil Williwaw in the late 1960s and sailed to New Zealand and back. It was a cruising boat to my eye. There is a video of Williwaw but I was unable to view it on my phone. Do google Williwaw trimaran. Good luck

[Sailmonkey]

I actually foiled this weekend. In the form it exists at this time, foiling is not suited to cruising vessels, for all of the reasons stated above, the extreme concentration required to maintain flight above all else. The sheer size and weight of the foils form roughly a third of the total weight of the platform i'm sailing on (flying phantom). Cruising cats have no business foiling with your average sailor, nor do mono's. If anything, the most likely scenario I see is leeboards to counteract heeling on monos, not full flight.

[Stumble]

Guys think of boat performance as a progression. At one end of the scale there are full displacement, full keel, attached rudder designs like an IP. From there you move up the performance gradient to skeg rudders, then spade rudders. Then cut back keels, Fin keels, bulb keels, canting keels, etc...

At the very very pointy end of the scale there is full foiling, then just below that is foil assist, then RM generating foils.

Right now the cruising world is still plugging along primarily in the slow end of the pool, and thats ok. Back there you have a lot of load carrying capability, moderate speeds, less cost, and easy to control boats. The further up the scale you go the less lad you can carry, the costs start to spiral out of control, the boats get hard to handle, but the speeds go up.

If you want to think about foiling then if you aren't already sailing a carbon trimaran you are kidding yourself. Right now you can go snatch up Paradox, a detuned Orma 60 for less than the cost of a set of foils for a 40' Catamaran and sail regularly at 30 knots. Even a Rapido 60 trimaran at $1.8 million with all the carbon upgrades will be sailing at 20-25 easily without foils and has a pretty nice interior for a boat that will average 400nm days with two aboard.

As always keep in mind if the goal is speed, then adding another hull is always going to be faster than adding foils. A performance 30' Catamaran without foils is going to be faster than the Figaro's. A Mod 70 is much faster than the mustachioed IMOCA's.

If you want to go fast buy a multihull, if you want to go faster buy a performance multihull, if you want to go even faster buy a stripped down racing multihull, if you still need more speed then consider a foiler.

[Stumble]

Originally Posted by Dave22q

Not being a marine engineer I have to rely on basic principles. Seems to me that lifting a hull by using foils makes a mono-hull more tender just as cutting off some keel would. it just seems dangerous to me- the combination of high speed and less resistance to a roll or pitch pole.

Just the opposite on monohulls. The foils on the Figaro's and IMOCAs actually generate RM. In effect they act like amas on a trimaran adding positive lift as far away from the main hull as possible. It's dynamic lift not static, but the same rules apply. Its part of what made the foiling IMOCA's faster, because of the extra RM they didn't need to be as wide. So the Gen3 foilers were actually the narrowest boats in years.

[barnakiel]

People look at that boat at #1 - it is a plain banana Opti!

It is NOT light - by any measure.

It is not high hp - by any measure.

It is not expensive.

Nor is it fast (it is said to be the slowest dinghy by the Portsmouth Yardstick).

My take - a well designed light displacement cruising boat (alike say a Juan K First 30) - updesigned and foiled up - WILL do it. Will foil. And will sail faster and be more stable in the whole process.

I think though that we will see fully foiling cruising cats up first - cats ARE the now and tomorrow of sailing. And because of lack of ballast and the config of the hulls they are the optimum (probably) platform to deploy foils on.

I think near future performance cruising mono will sport foils too.

b.

[a64pilot]

I don't think it is an Opti, yes it certainly looks like one. However in the video they plainly said they used graphene. I had to look that up, didn't sound cheap to me. Maybe just the foils though who knows?

There is obviously a speed at which you have to obtain to fly though, and that is going to be planing speeds I'm sure, so how many cruising boats plane? I don't know so don't shoot the messenger, but take the Gunboat for example, it's apparently difficult for the factory crew to handle.
Don't get me wrong, I'd love to see foiling cruising boats, but bet we will see flying cars first.
If you get one, please take me for a sail

[EzzyD]

Originally Posted by a64pilot

I don't think it is an Opti, yes it certainly looks like one. However in the video they plainly said they used graphene. I had to look that up, didn't sound cheap to me. Maybe just the foils though who knows?

There is obviously a speed at which you have to obtain to fly though, and that is going to be planing speeds I'm sure, so how many cruising boats plane? I don't know so don't shoot the messenger, but take the Gunboat for example, it's apparently difficult for the factory crew to handle.
Don't get me wrong, I'd love to see foiling cruising boats, but bet we will see flying cars first.
If you get one, please take me for a sail

gcaptain has an article where they claim that the opti in addition to the foil were made of graphene...

and going to the source ( CHALMERS UNIVERSITY OF TECHNOLOGY - SE-412 96 GOTHENBURG, SWEDEN - PHONE: +46 (0)31-772 10 00 - WWW.CHALMERS.SE ) we see that they also claim the dinghy was strengthened by graphine (not a 100% graphine hull) and the foil was made from graphine...

The optimist dinghy proves it can fly
Students and researchers at Chalmers and SSPA have together designed and developed an optimist dinghy with supreme capabilities. By using a composite with added graphene, the hull is made stronger and lighter. Hydrofoils are added to lift the boat, decreasing drag and allowing greater speeds. After tests performed in SSPAs towing tank, the dinghy was ready to be tried out at sea for the first time.
​A relatively new occurrence within the sailing world is to mount hydrofoils on small sailing dinghies. Chalmers and SSPA wanted the challenge to do this on “the world´s least advanced sailboat” – the optimist dinghy. The main question and problem for the students and the researchers of this project has been: can an optimist foil and how will this be done?

The optimist dinghy has, since it was conceived in 1947, become one of the world’s most popular sailing dinghies, with over 150 000 boats registered. The boat, only 2.3 metres in length and with a sail area of 3.3 square metres, is normally limited to speeds below 4 knots.

However, by building the boat in carbon fiber and graphene, and fitting it with hydrofoils lifting the hull out of the water, the hydrodynamic resistance can be reduced dramatically.

The hydrofoils, constructed and tested at SSPA, allowed the optimist dinghy to sail as fast as the wind in the recently conducted sea trials, achieving a maximum boat speed of 12 knots in only 12 knots of wind.

CONTACT PAGE RESPONSIBLE

Published: Fri 07 Apr 2017.

[Stumble]

It doesn't suprize me at all that someone got an Opti to foil, it's just a question of power weight. The Opti for all its issues isn't really that heavy of a boat, it just lacks much sail area. A bone stock standard Opti is 70lbs, with 35sqft of sail area. A foiling Moth all up weighs 65lbs but with 86ft^2 of sail area.

If all you did was plug the Moth foils onto an Opti you would be right around their design weight. You just need to wait for a breezy day to have enough power to foil. Now if you can cut the weight some, of course that's only going to help.