Foil Optimist

[Doug Lord]

Optifoil

Watch this-very little crew movement. Couldn't an opticrew hike diagonally and/or stand up?
https://www.youtube.com/watch?v=pFJ4eBpMs9o

 

[Doug Lord]

Optifoiler

Yes that's true, it's hard to have a good weight transfer on a optimist (same for the other boats) but it is possible. It's like every systems, if you just can have a small input on it but if it's enough for control, that works.
At my humble optinion, the good way to do that is to use 2 foils (rudder and daggerboard) with positive angle of attack but a llitle bit more for the rudder.
You can see on this video that the girl is behind the daggerboard.
https://www.youtube.com/watch?v=SlhD6G_6Bxs

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Very cool, Gurval -thanks! Seems to me the towline is way too low-should be at the same position as the CE of the sail? (to simulate pitch input of the sail)
I think with practice it can be done..... Probably easier to control under sail(after you get the hang of it)! Exciting stuff and well worth the effort!
https://www.youtube.com/watch?v=SlhD6G_6Bxs

 

[daiquiri]

Watch this-very little crew movement. Couldn't an opticrew hike diagonally and/or stand up?
https://www.youtube.com/watch?v=pFJ4eBpMs9o

I cannot watch the videos now. Will do later.

The Optimist is made for the simplest form of lean-back hiking, and doesn't have a rig equipped and sized for a trapeze. Don't forget it was made for a first approach to sailing for the kids. One first learns to walk, and only then he can try with running.

 

[Doug Lord]

Optifoil

I cannot watch the videos now. Will do later.

The Optimist is made for the simplest form of lean-back hiking, and doesn't have a rig equipped and sized for a trapeze. Don't forget it was made for a first approach to sailing for the kids. One first learns to walk, and only then he can try with running.

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I sure wasn't suggesting a trapeze! I was thinking that diagonal hiking might work for better control. And maybe standing up-if that's possible.

 

[Doug Lord]

Foiling (Optimist)

Opti Inspiration:

 

[CT249]

I wouldn't use kite and windsurf boards for comparison because they are very different kind of animals, relatively easy to control due to the body-mass to board-mass ratio. Basically, the CoG of kitesurfer's body is pretty much the CoG of the board + windsurfer. Similar situation for the windsurfers.
Furthermore, the apparent wind is very high (compared to the true wind), so the small true-wind perturbations are effectively damped by the high speed of the board.

In case of an Opti, the boat's weight is comparable to the body weight of the kids sailing it, hence a longitudinal body movement 2X is necessary to shift the boat's weight by X (in percentage). With their feet hooked to the hiking straps, it is a very hard task - absolutely not comparable to kiteboards and windsurfers.
Foiling speed is also necessarily lower in this case (just consider the weight and the anti-aerodynamic shape of an Opti boat), which means that any true-wind perturbance has a much bigger influence on the boat's dynamics. Hence a hypothetical foiling Optimist with that foil layout would likely require quite the oposite to what is available - quick and ample range of body movements, coordinated with an efficient sail and rudder control.

But that's just my two cents worth. I've been wrong many times before, and might be wrong in this case too. Time will tell.

Cheers

That's an excellent summary. Even the foiling Laser, which has the advantage of a wand for height control, requires fast and dramatic fore-and-aft weight shifting when foiling in puffy winds, in my very limited experience. Even if you're used to other classes where you move fore and aft dramatically (such as boards and trap boats) it's still difficult to physically fore and aft quickly on a hiking boat.

The other issue is that if you have a high or medium drag hull (like the Opti and Laser) you need powerful sails and sail setting to drive the boat onto the foils - but that becomes an issue as soon as you are foiling because then you need a low-drag rig. It's not a problem with the Moth, because the Moth already had a low-drag hull and a large but low-drag rig.

 

[CT249]

I disagree because of the huge difference in footprint---and because the designer thinks it would work.....

How do you know the designer thinks it would work? Didn't Gurval tell us that
"I know phillipe and this project was just to show something fun during"??

 

[Doug Lord]

It's in one of the links in the first post-and obvious from the design. http://segelreporter.com/regatta/jugendsegeln-franzosen-entwickeln-foiling-set-fuer-den-optimisten/ "The French have fixed wings mounted, which are then placed in the appropriate angular position with body weight shifts."
I guess I assumed they were quoting the designer.
Seems like once the crew gets the hang of it he/she would find weight shifting a lot of fun. And then there is the video showing a kid testing the concept of weight shifting for altitude control....
Technically, the Opti would have much more built in pitch stability than a windsufer foil like I showed above due to the large footprint and area of the foil system.
If they stay at it I'll bet they'll get the thing foiling well.

 

[Doug Lord]

Optifoiler

I've written to Erplast to try to get more info on the Optifoiler development....

 

[Skyak]

It's in one of the links in the first post-and obvious from the design. http://segelreporter.com/regatta/jugendsegeln-franzosen-entwickeln-foiling-set-fuer-den-optimisten/ "The French have fixed wings mounted, which are then placed in the appropriate angular position with body weight shifts."
I guess I assumed they were quoting the designer.
Seems like once the crew gets the hang of it he/she would find weight shifting a lot of fun. And then there is the video showing a kid testing the concept of weight shifting for altitude control....
Technically, the Opti would have much more built in pitch stability than a windsufer foil like I showed above due to the large footprint and area of the foil system.
If they stay at it I'll bet they'll get the thing foiling well.

Doug, have you ever windsurfed? What you are missing is that the Opti does not have the freedom of movement it takes to balance -let alone control height. Having the mast angle fixed to the foil angle pretty much dooms any chance of control. The weight of the crew would have to rocket around in 3D to counter variations in wind. I tried to describe it back in post 5 but you ignore it.

It will be be interesting what the builders say about the OP foiling Opti -do share.

I sure wish we had a consistent way to quantify how hard a boat is to balance -like the control needed to counter a 30% increase in wind speed, or a tack, or a gybe...

Any ideas daiquiri?

 

[Doug Lord]

Yes-a lot. I also designed and built the first production catamaran windsurfer in the US-the Kona Kat.
I disagree 100% with your assessment of the possibility of a kid learning to foil an Optifoiler! All you have to do is watch the video's I posted earlier to realize that it won't require dramatic movement (most of the time)-because the Optifoiler has better designed-in pitch control than a kitefoiler or foiling windsurfer to start with. Once they get the hang of it it will be a blast!


Pix-Me,Tom Knight,Rosy (and her wonderful dog), Tom again- testing:

 

[daiquiri]

Any ideas daiquiri?

There is also a possibility of controlling the Opti's dynamics with the rudder and the sail. But the problem I see is the absence of any form of automatic flight-level control. There will be a lots of ditching and pitching-up, and take-offs will be a funny stuff to watch...
Kids are amazing at learning and acquiring new abilities, that's beyond any doubt, and I do not exclude that some of them shall make it to control that boat for a certain amount of time, in stable wind conditions. But I do think that it will be a very hard task with the actual fixed-foil configuration.

 

[Doug Lord]

Optifoiler

Slavi, I think they're going in the right direction-IF they can reasonably learn to fly with the current system it is much simpler than adding a wand+flap and therefore less expensive. It won't be as easy to learn but once learned it won't be forgotten-I hope it works out.....

 

[Doug Lord]

Optifoiler

I've written to Erplast to try to get more info on the Optifoiler development....

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Response from Erplast is:
"For the moment we are still working on it. You should be able to get some information from our Facebook page. Do not hesitate to keep following us."

Erplast Facebook: https://www.facebook.com/ERPLASTnautic

 

[daiquiri]

Response from Erplast is:
"For the moment we are still working on it."

Oh yes, I believe so. There is still a lots of work which needs to be done before seeing it fly in a stable manner.
I dare to say that the final version (should they keep working on that concept) will be very different from what was shown in the previous pics.