THE IMOCA thread, single/double handed & TOR

blunderfull

blunderfull

Super Anarchist
4,480
770
Huntington Beach, CA
Contrast between cabins of Malizia and Medallia really threw me. Medallia is spartan with those two beams running thru the center at shoulder height. Would not want to get tossed around in there. Is there a seat somewhere? The main screen appears to be at knee height? When laying down it’s eye level but how to comfortably view when not in the bunk? Pip’s video was short so maybe there’s more to see on how it all comes together when racing?

The big roomy cockpit (one level) on Malizia looks pretty well layed out. Easy access to all the comm stations and so forth. I particularly like the big, forward looking viewing ports on either side.

The start of the race should be a real banger if that predicted weather fills in.

I was in Newport RI for the start of the ‘86 BOC and that was memorable. Can’t get enough of these great solo sailors. Think I’ll watch ‘Coyote’ again.
 
Varan

Varan

Super Anarchist
6,872
2,062
Charal 2 really is an interesting Imoca. Round and skinny. The seahorse issue referred to a few posts back has a photo of Charal 2 next to Charal 1, with one third of 1's bow sticking out past 2's. Interesting photo that highlights the fulness of 2's front end. Yet it is the narrowest of modern imocas.

Manuard notes that even with the new restrictions on foil sizes, they still provide sufficient RM that max beam is no longer necessary, but with a narrow hull, it is still important to provide sufficient volume forward. Hence the scow-bow. What I found especially interesting is his discussion of chines, most pronounced around the bracing for the outriggers. The outrigger tie rods, outriggers and mast are one design, so the chines widen this narrow boat where outrigger cables attach.

The most novel feature imho are the long, skinny rudders. The cant angle between them is 60 degrees. So when the leeward rudder is vertical, the windward one is 30 degrees from horizontal, able to provide significant lift when immersed. To keep it immersed, Charal 2 is designed to fly at relatively low heights. Leeward rudder controls yawl, windward controls pitch. Because of the surface-piercing nature of the windward rudder, it will ventilate near cavitation speeds, so instead of bursts of 40 kts followed by crashes reducing speeds to 10 kts, their goal is sustained 25 kt averages under autopilots.

The big risk, and it is a big one, is a collision with a UFO. Two long skinny rudders immerging from the centerline can both be taken out at once. Avoiding contact will be key to their success.
 
Sailbydate

Sailbydate

Super Anarchist
12,138
3,623
Kohimarama
Varan said:
Charal 2 really is an interesting Imoca. Round and skinny. The seahorse issue referred to a few posts back has a photo of Charal 2 next to Charal 1, with one third of 1's bow sticking out past 2's. Interesting photo that highlights the fulness of 2's front end. Yet it is the narrowest of modern imocas.

Manuard notes that even with the new restrictions on foil sizes, they still provide sufficient RM that max beam is no longer necessary, but with a narrow hull, it is still important to provide sufficient volume forward. Hence the scow-bow. What I found especially interesting is his discussion of chines, most pronounced around the bracing for the outriggers. The outrigger tie rods, outriggers and mast are one design, so the chines widen this narrow boat where outrigger cables attach.

The most novel feature imho are the long, skinny rudders. The cant angle between them is 60 degrees. So when the leeward rudder is vertical, the windward one is 30 degrees from horizontal, able to provide significant lift when immersed. To keep it immersed, Charal 2 is designed to fly at relatively low heights. Leeward rudder controls yawl, windward controls pitch. Because of the surface-piercing nature of the windward rudder, it will ventilate near cavitation speeds, so instead of bursts of 40 kts followed by crashes reducing speeds to 10 kts, their goal is sustained 25 kt averages under autopilots.

The big risk, and it is a big one, is a collision with a UFO. Two long skinny rudders immerging from the centerline can both be taken out at once. Avoiding contact will be key to their success.
Click to expand...
I wonder if maybe, there's another issue too, Varan. i.e. That this windward rudder generated lift might/could compromise her snub bow's ability to pitch, particularly if she drives into the back of a large swell. Interesting times ahead. Apparently, there's been some dockside scuttlebutt about the rudder set up. Have you heard any negative feedback about Rule cheating?
 
L

LeoV

Super Anarchist
13,513
4,395
The Netherlands
Varan said:
The most novel feature imho are the long, skinny rudders. The cant angle between them is 60 degrees. So when the leeward rudder is vertical, the windward one is 30 degrees from horizontal, able to provide significant lift when immersed. To keep it immersed, Charal 2 is designed to fly at relatively low heights. Leeward rudder controls yawl, windward controls pitch. Because of the surface-piercing nature of the windward rudder, it will ventilate near cavitation speeds, so instead of bursts of 40 kts followed by crashes reducing speeds to 10 kts, their goal is sustained 25 kt averages under autopilots.
Click to expand...
Thanks, so in other words, experiment is ongoing. Nice to see.
 
Varan

Varan

Super Anarchist
6,872
2,062
Sailbydate said:
I wonder if maybe, there's another issue too, Varan. i.e. That this windward rudder generated lift might/could compromise her snub bow's ability to pitch, particularly if she drives into the back of a large swell. Interesting times ahead. Apparently, there's been some dockside scuttlebutt about the rudder set up. Have you heard any negative feedback about Rule cheating?
Click to expand...
The Seahorse article has several paragraphs discussing class rules in regards to rudders. A rudder is defined as a movable hull appendage principally used to influence yaw and not designed to produce lift, but every rudder generates lift at non-vertical angles. NOR also replaces RRS 52 noting in regards to autopilots that all servo systems are prohibited with the exception of rudders to affect yaw. Jean Sans (technical advisor) opinion is that since non-vertical rudders affect both pitch and yaw, rudders can be controlled with independent rams.

This is likely the source of the controversy. Can the rudders be separately controlled? Charal 2 is proceeding as if the answer is yes, but surely they are prepared to link the rudders if required, and will still likely realize benefits from their design, just not as much as when independently controlled.

In regards to the ability to control the bow's pitch, that is the main benefit of independently contolling the near horizontal foil. Turn it one way to raise the bow, the other way to lower it, with the goal of achieving level flight.
 
H

Haligonian Winterr

Super Anarchist
1,503
66
Halifax, NS
Varan said:
The Seahorse article has several paragraphs discussing class rules in regards to rudders. A rudder is defined as a movable hull appendage principally used to influence yaw and not designed to produce lift, but every rudder generates lift at non-vertical angles. NOR also replaces RRS 52 noting in regards to autopilots that all servo systems are prohibited with the exception of rudders to affect yaw. Jean Sans (technical advisor) opinion is that since non-vertical rudders affect both pitch and yaw, rudders can be controlled with independent rams.

This is likely the source of the controversy. Can the rudders be separately controlled? Charal 2 is proceeding as if the answer is yes, but surely they are prepared to link the rudders if required, and will still likely realize benefits from their design, just not as much as when independently controlled.

In regards to the ability to control the bow's pitch, that is the main benefit of independently contolling the near horizontal foil. Turn it one way to raise the bow, the other way to lower it, with the goal of achieving level flight.
Click to expand...
Even if the rudders have to be linked eventually, you can do ALOT with the toe bar, particularly if it's already being actively driven for the pilot. Remember pilots can also be programmed to drive to whatever parameter you want (including ride height).
 
W

winchfodder

Super Anarchist
1,885
437
Carolina, USA
Varan said:
Charal 2 really is an interesting Imoca. Round and skinny. The seahorse issue referred to a few posts back has a photo of Charal 2 next to Charal 1, with one third of 1's bow sticking out past 2's. Interesting photo that highlights the fulness of 2's front end. Yet it is the narrowest of modern imocas.

Manuard notes that even with the new restrictions on foil sizes, they still provide sufficient RM that max beam is no longer necessary, but with a narrow hull, it is still important to provide sufficient volume forward. Hence the scow-bow. What I found especially interesting is his discussion of chines, most pronounced around the bracing for the outriggers. The outrigger tie rods, outriggers and mast are one design, so the chines widen this narrow boat where outrigger cables attach.

The most novel feature imho are the long, skinny rudders. The cant angle between them is 60 degrees. So when the leeward rudder is vertical, the windward one is 30 degrees from horizontal, able to provide significant lift when immersed. To keep it immersed, Charal 2 is designed to fly at relatively low heights. Leeward rudder controls yawl, windward controls pitch. Because of the surface-piercing nature of the windward rudder, it will ventilate near cavitation speeds, so instead of bursts of 40 kts followed by crashes reducing speeds to 10 kts, their goal is sustained 25 kt averages under autopilots.

The big risk, and it is a big one, is a collision with a UFO. Two long skinny rudders immerging from the centerline can both be taken out at once. Avoiding contact will be key to their success.
Click to expand...
I see that Apivia sails with windward rudder lifted, is it the case that it cant be used as a foil with lift?
 
Raptorsailor

Raptorsailor

Anarchist
918
310
The sea


In this video, Charal team member claims the boat has been optimised (to an extent) for upwind sailing in comparison to all other IMOCA's near the end of the video. We've seen in the past that if you want a boat that is an absolute scorcher upwind you end up with an IACC or in the present, an AC75. If you want a rocketship downwind, you build a sled, like an IMOCA, or a skiff. I don't see how you can make an IMOCA incredibly fast upwind AND downwind without proper foiling in the present day.
I think the only reason Charal has gone down this route is because they believe (at the design stage) that the speeds downwind would be competitive enough to offset the losses of more optimisation for upwind. The Vendee, a race for which the IMOCA is exclusively designed for is ~90% downwind with only the return part of the South Atlantic and finish being upwind. Why would you put yourself in a position where you need that extra upwind speed to keep a rival at arms length/save your lead when you could design a boat that is so bloody fast downwind that it doesn't need that extra trick up its sleeve. That was the design philosophy of the 2016 HB which was in a league of its own, the 2020 HB which might have been in a league of its own, we'll never know, and quite probably the same philosophy used by Apivia.....

I don't see Charal 2 being good enough to win the VG. But time will tell, maybe they're onto something. Oh and the ergonomics and protection from the elements of that cockpit are truly crap compared to other boats.
 
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