Syroco proposal for Sailing Speed Record Challenger

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John Perry
AYRS Chairman
Posts: 81
Joined: Tue Nov 08, 2016 6:39 pm

Syroco proposal for Sailing Speed Record Challenger

Post by John Perry »

AYRS member Neils Daken has passed me a link to a new proposal to challenge for the world sailing speed record - https://syro.co/en/speed-record/

This is a concept that AYRS members, myself included, have discusssed over and over again during Weymouth Speedweeks and AYRS technical meetings, but there is a big gap between talking theory and making an actual record attempt!

Robert Biegler
Established member
Posts: 47
Joined: Sun Jan 08, 2017 7:54 pm

Re: Syroco proposal for Sailing Speed Record Challenger

Post by Robert Biegler »

Syroco looks to me like Jon Howes’ Monofoil with a kite instead of a wing. The most significant difference seems to be that Syroco is supposed to tack, though I don't understand how that is supposed to work. Maybe the apparent tack is only an illustration that Syroco can sail on both tacks. With the fuselage not having a circular cross section, the bottom wouldn't look the same if the foil swung to the other side as shown.

It is also not clear to me how they intend to steer. If they can control the angle of the foil relative to the strut, that should do the job, but I see nothing like this in the video. I suppose the rudder in the air can steer to some extent, at the cost of additional drag when the fuselage doesn't align with airflow.
If Syroco’s fuselage aligns with airflow, the pilot either has to be really confident of avoiding any touchdown at speed, or confident that the fuselage can skip over the water at an angle without capsize or a whiplash-inducing course change.

John Perry
AYRS Chairman
Posts: 81
Joined: Tue Nov 08, 2016 6:39 pm

Re: Syroco proposal for Sailing Speed Record Challenger

Post by John Perry »

Hi Robert
Did you find a video on the Syroco web site? - I did not see one there but looking at U tube I did find there is a Syroco U tube channel with, I think, 4 videos currently on it. These videos give a better idea of the concept than the Syroco website. It is clear from these videos that the hull does not revolve arround its longitudinal axis when the craft tacks. There appears to be a cylinder within the hull with an axis of revolution parralel to the long axis of the hull. The kite lines are attached to one side of this cylinder and exit the hull through some sort of sliding hatch in the top of the hull, the hydrofoil strut is attached diametrically oposite on the cylinder and exits the bottom of the hull through a similar sliding hatch. So the hull does not have to tip over as the craft tacks. They are clearly thinking of a supercavitating hydrofoil and in one of these videos they seem to be saying that this will have reduced drag due to avoiding skin friction of water on the low pressure side of the foil. That does not quite fit in with what I have read elsewhere about supercavitating hydrofoils. As for the result of the hull touching the water, assuming it is aligned with the apparant wind, I see the hull is flat bottomed so maybe it is meant to just skid a bit sideways on the water. And it has a small fin underneath - perhaps that fin is steerable so as to guide the hull on a smooth path at touch down, rather than suddenly switching direction. Just guessing.

I feel a bit annoyed when people put forward proposals such as this as being completely new concepts. The basic idea of ballacing a wing, or kite, in the air against a foil acting in the opposite direction under water has been discussed by AYRS members for as long as I can remember. It is of course the basis of the current world speed record holder Sailrocket, and as you say, has been built, as a model at least, by Jon Howes, Giles Whitaker, Roger Glencross and others. There are variations on the theme. The link between hydrofoil and aerofoil can be a streamlined strut or it can be one or more cords/ropes. The aerofoil can be a collapsable kite, or it can be a ridgid wing. The hydrofoil can be an inverted Tee foil with an appropriate depth control system, or it can be a 'hook' style foil that can be inherantly stable in depth. Steering and attitude control can be by control surfaces in the water and/or in the air. Control surfaces in/on the water can take the form of additional hydrofoils, or they can be planing 'skids' as Sailrocket has. Somewhere there has to be a structure that provides bouyancy when the craft is at rest and which carries the payload of a crew. You can mount this structure from the hydrofoil in which case you will probably call it a hull, or you can mount it from the wing/kite in which case you will probably call it a fusilage. Or you can suspend it somewhere midway between the two. You can make it to alighn with the apparant wind, or not. So multilying together all such possibilities you get a fair number, but a finite number, of possible options. I think it might be fun to list and sketch all these options as a piece for Catalyst. Or we can talk about it at one of our Zoom meetings.

As I said before, there is a big gulf between discussing concepts and bringing a craft to a speed record course. So far AYRS member Paul Larsen and his team are the only people to have successfully achieved this. The Syroco people seem to have a big team, maybe lots of funding, and impressive computer graphics but as far as I can see not a lot else - so far. This could of course all change pretty quickly - we have seen how French teams have completely taken over the sport of multihull ocean racing!

Robert Biegler
Established member
Posts: 47
Joined: Sun Jan 08, 2017 7:54 pm

Re: Syroco proposal for Sailing Speed Record Challenger

Post by Robert Biegler »

John Perry wrote:
Fri Oct 23, 2020 11:09 pm
Did you find a video on the Syroco web site?
The link that I originally followed was to this video: https://www.youtube.com/watch?v=Blb2S6Ytngg
John Perry wrote:
Fri Oct 23, 2020 11:09 pm
It is clear from these videos that the hull does not revolve arround its longitudinal axis when the craft tacks. There appears to be a cylinder within the hull with an axis of revolution parralel to the long axis of the hull. The kite lines are attached to one side of this cylinder and exit the hull through some sort of sliding hatch in the top of the hull, the hydrofoil strut is attached diametrically oposite on the cylinder and exits the bottom of the hull through a similar sliding hatch. So the hull does not have to tip over as the craft tacks.
That was my initial interpretation of what that video shows from 0:44 to 0:47. I had second thoughts because no such ring is shown either protruding from the flatter than circular bottom at 0:35 or 0:58, nor any protrusion as on the AC75s. 0:58 seems to show some panels distinct from the fuselage, but to remain flush with the hull bottom, the lower panel would have to deform as the foil swings from one side to another. The flat bottom would have to be really important to be worth the bother. Maybe it is.
John Perry wrote:
Fri Oct 23, 2020 11:09 pm
They are clearly thinking of a supercavitating hydrofoil and in one of these videos they seem to be saying that this will have reduced drag due to avoiding skin friction of water on the low pressure side of the foil. That does not quite fit in with what I have read elsewhere about supercavitating hydrofoils.
She first mentioned improved control, but yes, then seemed to imply reduced drag.

Jon Howes has a few interesting things to say about a ventilating profile he first designed for Monofoil, then adapted to a foiling dnghy intended to be simpler than those with wand-controlled foils: https://www.boatdesign.net/threads/toma ... ost-263509 Look for several posts by Jon Howes and where he is quoted from a thread elsewhere.
John Perry wrote:
Fri Oct 23, 2020 11:09 pm
As for the result of the hull touching the water, assuming it is aligned with the apparant wind,
The fact that the rudder (the one in the air) is shown as aligned with the fuselage is consistent with that, but it could also be that they didn't think it worth the bother to show any other setting in that animation.
John Perry wrote:
Fri Oct 23, 2020 11:09 pm
I see the hull is flat bottomed so maybe it is meant to just skid a bit sideways on the water.
And perhaps that is the reason.
John Perry wrote:
Fri Oct 23, 2020 11:09 pm
And it has a small fin underneath - perhaps that fin is steerable so as to guide the hull on a smooth path at touch down, rather than suddenly switching direction. Just guessing.
I somehow managed not to notice that fin.
John Perry wrote:
Fri Oct 23, 2020 11:09 pm
I feel a bit annoyed when people put forward proposals such as this as being completely new concepts. The basic idea of ballacing a wing, or kite, in the air against a foil acting in the opposite direction under water has been discussed by AYRS members for as long as I can remember.
I agree. Monofoil was just the closest match that came to my mind. We could add Haagedorn's ultimate sailing paper and the designs of Bernard Smith and of Didier Costes to the list of prior art. I was tempted to say these teams (there is also SP80: https://www.youtube.com/watch?v=NKHQF2L3vPM and https://www.youtube.com/watch?v=ywNeh_qQZpo) came up with the same idea independently, but they can hardly be into speed sailing and not know of Sailrocket.
John Perry wrote:
Fri Oct 23, 2020 11:09 pm
So multilying together all such possibilities you get a fair number, but a finite number, of possible options.
192 of them. It would take a while to discuss their relative merits, at least if the features can't be discussed independently.

I do like the idea of having only a single foil in the water, and controlling pitch by an airfoil. If I remember correctly, Macqarie innovations crashed because a wave bounced a hull and the foil underneath it out of the water. Jon Howes suggested the Monofoil could set records offshore because it could avoid that problem. I guess that assumes that airflow just above the water is not turbulent enough to make pitch control even worse. But if it were, wouldn't that make trouble for seaplanes?

Regards

Robert Biegler

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