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New imoca boats

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5 hours ago, serialsailor said:

Charal reaching.

At 2'48 the hull doesnt touch the water for a fraction of a second...

They are going to need t rudders really soon, or they are going to encounter the same problem as the ORMAS  in the 2000s

the lifting power of those foils is a seriously brute force.

what were the problems the ORMA's we're having, lifting then falling?

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6 hours ago, serialsailor said:
They are going to need t rudders really soon, or they are going to encounter the same problem as the ORMAS  in the 2000s

I guess T rudders prevented by IMOCA class rules?

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I thought the hull was not allowed to be completely out the water? I thought I read something on that IMOCA rule? How were they not winning the race? Bad start? Or the others got an early jump?

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Some real interesting stuff has come from this event.

The older generation of boats that have been re-moded with dali foils are reborn, but still represent a notch down from from the new elite, as you would expect.

VR's work to PRB is top notch and very considered.

Upwind trim seems from the video to be a little bit hit and miss - I know that is not what these boats are built for, but first few hours are often upwind, and come VG the slog back from Falklands to equator can have significant close winded stretches.

The no show by HB is a shame, but not unexpected. Is there any intell on what foils they are currently running?

Charal's withdrawal from the race is a pity but still early days, and their high speed run confirmed the thoughts of post #2078 - high angle of heel, two distinct set of waterplanes, keeping the immersed rudder at a near vertical aspect, etc.

The takeaway for me will be how important the stacking of the boat will be, to maintain not only free RM but also maintaining the fore and aft trim that really unleahes the high top speeds. Very easy to just place everything where the boat is widest, but if you drag that arse too much it will sap speed very quickly, and the lack of T's on the rudders makes the sweet spot pretty twitchy I would imagine.

I wondered if the foils looked overspec'd in area, but remember we are looking at a speed runs in flat water, whereas "out there" it's not....

Seems the boats need lots of active management to keep them humming, so whilst the skippers are hardly ever steering - they are not exactly feet up with a good book. Effort in, directly translates into results out. VR and his ilk can offset somewhat, not having the absolute latest optimal design. 

November's race will give us lots more to consider

 

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20 minutes ago, terrafirma said:

I thought the hull was not allowed to be completely out the water? I thought I read something on that IMOCA rule? How were they not winning the race? Bad start? Or the others got an early jump?


Can't use two foils at once to lift hull out of water. No T rudders. 

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1 hour ago, Miffy said:


Can't use two foils at once to lift hull out of water. No T rudders. 

You mean like the keel foil and the leeward foil///  That looks like what they are doing :)

 

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2 minutes ago, dachopper said:

You mean like the keel foil and the leeward foil///  That looks like what they are doing :)

 

No I mean having both foils down at the same time and foiling the actual hull out of the water. The keel is the keel. 

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Well.... The keel used to be just the keel but if you can pivot that thing a little left and right or fore and aft ...... it's no longer just a keel!!!!

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Nice promo video of Charal that includes a bit of everything. Love these boats....

 

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18 hours ago, 3to1 said:

the lifting power of those foils is a seriously brute force.

what were the problems the ORMA's we're having, lifting then falling?

Yes.

And it is already happening to Charal. Just look on this video at 1:02.

 

The boat lifts up, the sails go flapping, the foil stalls and back down we go. Then the boat regain speeds until it goes sufficiently fast that the foil has too much lift and around we go again..

Beyou gave an interview to Le Télégramme with this quote :

"A la barre, c'est chaud. Il faut qu'on calme le jeu les gars, on va passer sous J3 ". 
Trop de toile à l'avant et surtout trop de foil. En résumé, trop de chevaux sous le capot. Le 60 pieds a été conçu pour décoller à partir de 13-14 nœuds. Il y a 20-25 nœuds dans les courreaux de Groix... 
quick trad:
"at the tiller it is hard. We have to calm things down guys, we will change to J3
Too much sail upfront and more importantly too much foil. to put it quickly, too much horsepower. The 60fter was conceived to start foiling in 13-14 knt TWS. There is 20-25 knt in the straight of Groix"
 
So this boat apparently has a lot of foil RM to start foiling early. I guess here they were trying to push it as hard as possible, causing the boat to stall sometimes. But you can see who fast the boat is going when it stays in the right attitude, its amazing. With often only 1/3 or 1/4 of the boat's length touching the water.

 

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A friend who works for Alex Thomson told me that the boats are odd to sail and you get totally unnatural lee helm if you hand steer. By comparison a mod70 felt 10x better to drive!

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5 hours ago, serialsailor said:

Yes.

And it is already happening to Charal. Just look on this video at 1:02.

 

The boat lifts up, the sails go flapping, the foil stalls and back down we go. Then the boat regain speeds until it goes sufficiently fast that the foil has too much lift and around we go again..

Beyou gave an interview to Le Télégramme with this quote :

"A la barre, c'est chaud. Il faut qu'on calme le jeu les gars, on va passer sous J3 ". 
Trop de toile à l'avant et surtout trop de foil. En résumé, trop de chevaux sous le capot. Le 60 pieds a été conçu pour décoller à partir de 13-14 nœuds. Il y a 20-25 nœuds dans les courreaux de Groix... 
quick trad:
"at the tiller it is hard. We have to calm things down guys, we will change to J3
Too much sail upfront and more importantly too much foil. to put it quickly, too much horsepower. The 60fter was conceived to start foiling in 13-14 knt TWS. There is 20-25 knt in the straight of Groix"
 
So this boat apparently has a lot of foil RM to start foiling early. I guess here they were trying to push it as hard as possible, causing the boat to stall sometimes. But you can see who fast the boat is going when it stays in the right attitude, its amazing. With often only 1/3 or 1/4 of the boat's length touching the water.

 

wonder if retracting the leeward foil some would help keep the boat in a groove at boat speeds of around 25 knots plus, and if it's that simple?

irrelevant, but to my eye, the size of those foils looks a little over the top, but with the amount of reaching during a Vendee, foils with that kind of power have to be the hot set up if they don't get mangled.

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I may be seeing things, but is that the keel bulb cavitating when Charal stalls? Or did she just suck a bunch of air down the foil?

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17 hours ago, r.finn said:

J3 conditions for sure.  The J3 video from that day looks much better.

 

You are right I didn't realize that this shot was when they were still under J2. Too much power as beyou said.

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Can someone remind me.  Did Imoca go one design keel when they went one design (two design) masts?  If so are they a single manufacturer or do you build your own from approved plans?  Carrying the boats in this way would fall a long way out of the original design concept and fatigue will be through the roof.

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Imoca has had a one design fin for the past generation or so. Referred to regularly in other press, including current Seahorse

Not sure on the bulb design.

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6 hours ago, SCARECROW said:

Can someone remind me.  Did Imoca go one design keel when they went one design (two design) masts?  If so are they a single manufacturer or do you build your own from approved plans?  Carrying the boats in this way would fall a long way out of the original design concept and fatigue will be through the roof.

Yes same time as the mast(s)

Single keel-strut manufacturer (milled steel)

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2 hours ago, moody frog said:

Yes same time as the mast(s)

Single keel-strut manufacturer (milled steel)

I bet they're just loving watching boats foil on their product.  My prediction is we're going to see keel failure re-emerge as an issue in this class.  particularly  as lower budget teams try to take second hand foilers for another lap.

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On 9/24/2018 at 9:26 PM, 3to1 said:

wonder if retracting the leeward foil some would help keep the boat in a groove at boat speeds of around 25 knots plus, and if it's that simple?

irrelevant, but to my eye, the size of those foils looks a little over the top, but with the amount of reaching during a Vendee, foils with that kind of power have to be the hot set up if they don't get mangled.

Formula 1 running on 2 wheels. Scary and phenomenal at the same time.

 

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On 9/24/2018 at 3:14 PM, terrafirma said:

Nice promo video of Charal that includes a bit of everything. Love these boats....

 

Amazing machine. Can't wait for the next VG.

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Charal seems a fair bit beamier than Hugo Boss but perhaps narrower than the other existing foilers etc what do we all think Alex has gone with in terms of his new boat? Does anyone have the actual beam comparisons of the boats including Charal? With the bigger more powerful foils what beam would you all be going with? 

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14 hours ago, SCARECROW said:

I bet they're just loving watching boats foil on their product.  My prediction is we're going to see keel failure re-emerge as an issue in this class.  particularly  as lower budget teams try to take second hand foilers for another lap.

Thats a very broad brush statement - I agree budgets can determine outcomes when choices have to be made. However, the skippers are somewhat involved in the outcome of catastrophic failure.

What I feel is more relevant is that the engineering and design of the fins is "locked in", and comes from a period where the fin was sought to generate lift from inclinced keel pins and bulb placement that induced lift, and ultimately reduced RM. The internal structure of webs and welds was all custom catered for this scenario.

The findings of more recent development, particulrly that of the last VOR was that this lift generated was at the expense of too much drag - and that the boats ran faster when not necessarily at max cant. (Though again recent anecdotes suggest this is not a linear relationship.)

However, if you now want to seek ultimately higher power solutions with Dali foils, then too much lift from the keel fin is detrimental. Remember that fin twist can be tuned by very careful bulb placement. Farr used to invoke fin twist in VO60's with L shaped fin and bulb packages. Go the other way and hang the bulb's COG forward of the fin's COE and you can do the opposite - but you need to get some very carefully calculated and repeatable materials response to make this manageable, you are trying to suspend a Bulb for RM generation as well as not detrimentally alter leeway resistance.

The whole package is moving in in all axis of free movement. At vertical the relationship of COG to COE between Bulb and fin is neutral. At max cant, any lateral displacement between the COG to COE position will induce the most amount of of twist on the fin. So on fixed keel(fin) boats e.g. VO60 - at moderate heel, the fin twist gave useful Fin twist to reduce leeway - that only became increasingly unhelpful in terms of RM at the moment that a broach was about to happen. 

So returning to the canting keel situation. Can you find a sweet spot where the fin is sufficiently canted (Above 45 degrees would be an obvious scenario - where leeway resistance is diminishing) where the mass of the bulb and combined hydrodymanic forces of water velocity on both bulb and fin could induce leading edge droop?  - thereby increasing overall RM. Can mild steel fins be even that predictable in response in such a repeatable manner? And assuming that any of this is possible - will the additional RM plus Bulb Mass take the fin into an overstressed load carrying capacity? And again, if these loads are manageable, can the bearings, rams and hull mounts also take the additional load?

The attachemnt of the bulb to fin would only be altered fore and aft by very small increments - but unlike carbon fibre where extra laminations can be added or subtracted to tune twist, mild steel would have relatively coarse behaviours of elasticity, directly related to material thickness and even weld proportions.

The whole fin, ram, bearing package was engineered under different assumptions - as a one design package to reduce cost and increase survivability - so you would imagine that they are substantially over-specified, and also highly durable, to answer the orignal question. And I would make a sportsmans wager that the likes of GV and VPLP have looked at these with great levels of thought.

The comments following the amount of spray caused by the fin during the high speed runs are suggesting that the optimum is far away. Sucessful foiling solutions are usually characterised by their clean wakes. (yes, I know these boats are not true foilers)

I wrote elsewhere that fore and aft trim would be critical to unleashing fast runs, rather like I14's running minimal foil does. It all become edgy but fast. Is that the key right now? Or are designers seeking the extra mechanical RM that can be generated in what is otherwise a restricted box rule. More likely that it will be a combination of both. 

The comments in last months Seahorse from Rob Weiland and James Dadd, regarding Imoca doing both VOR and VG are interesting. Will having a compromise solution, dilute what is right now a very interseting design space? Can the two diverse set of requirements, even be contained within one design solution? I kinda of hope that the next VOR stays VO65 for just the next edition; whilst those questions get thoroughly explored and answered.

Nothing like half baked, quickly proposed solutions to spoil both races - The VG is as big as it has ever been, great boats, sailors, stories and massive marketing potential  - whilst the VOR has ridiciously tight racing at a known "cost to play equation" - its just the sailors who aren't enjoying it.......(It is the NasCar or Super V8's of the sailing world - far from pure, but serves its purpose, master, spectator very well)

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My concern isn't about actual loads but the frequency of load direction and magnitude changes.  Fatigue is a really hard thing to design / calculate. 

Don't get me wrong, I love the direction these boats are going.  Its just scary as fuck.

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speaking of fatigue, anyone here know if a milled titanium keel strut would be more fatigue resistant than a steel one? titanium bicycle frames, for example, tend to have longer life spans than steel before cracking.

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3 hours ago, Boink said:

 

 

 

 Farr used to invoke fin twist in VO60's with L shaped fin and bulb packages.

those bad-assed L-keel Farr VO60's will always be one of my all time favorite boats, don't seem to be many pictures of them around, either.

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then why do Ti bike frames out last steel (and obviously put aluminum ones to shame regarding fatigue)?

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Tit bikes do not last longer, the filter bumps better. At least in MTB world. If they last longer it because the owners are more carefully.
Look at how old steel frames are still riding, friend still cycling on his 1950's model, many out of the 60 still around.

 

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fair enough, but those old 50's and 60's steel frames are relatively 'overbuilt' (and used lugs), no? 

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5 hours ago, terrafirma said:

Charal seems a fair bit beamier than Hugo Boss but perhaps narrower than the other existing foilers etc what do we all think Alex has gone with in terms of his new boat? Does anyone have the actual beam comparisons of the boats including Charal? With the bigger more powerful foils what beam would you all be going with? 

myself, I'd do pretty much what Charal did with hull beam, reduce all unnecessary form drag and let the foils do their work.

if I was designing one of these foilers, I'd design the boat around the foils, not the foils around the boat.

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It is interesting to look at the IMOCA 60 rule. It is pretty prescriptive about the design of the fin. 

Page 36/37 http://www.sailing.org/tools/documents/ClassRulesIMOCA2018V1.0-[23695].pdf

Materials and resonant frequencies defined. However I would worry that some of these numbers may need revisiting in the light of a keel fin half out of the water and the other half ventilating right down to the keel bulb. Assumptions about the amount of damping and the frequencies of vibrations seen may be way out. In principle I would imagine the stresses would actually be less than the slamming loads the fin was originally envisaged to be subjected to. But weird things can happen. This thing looks to have the possibility of finding a whole new family of failure modes.

 

 

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you mean like aircraft wing 'flutter', or just torque and unusual loads on the keel fin and pivot?

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I doubt you would see flutter in a solid steel fin. But loads in the pivot could be pretty interesting. 

Then again, a flutter like end to end torsional mode could lead to pretty catastrophic issues.

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I will start by saying that I am not a multihull guy. But looking at the video of Macif on front page, if you want to foil, just go play multihulls. Monohulls just look awkward trying to copy them. Foils work with the multi platform structure, they don’t with a mono structure.

i will stick my neck out and say that using foils for RM and reaping the benefits of reduced weight/WSA is the natural limit of benefits for a mono.

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On 10/1/2018 at 6:47 AM, Francis Vaughan said:

I doubt you would see flutter in a solid steel fin. But loads in the pivot could be pretty interesting. 

Then again, a flutter like end to end torsional mode could lead to pretty catastrophic issues.

I wouldn't be so sure, if one resonant mode is wrong, any wing will flutter. Vibrations aren't easy to "guesstimate", sometimes engineers think that they've nailed it and an unexpected resonant mode appear, one good example is the millenium bridge : https://en.wikipedia.org/wiki/Millennium_Bridge,_London#Resonance

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9 hours ago, Chimp too said:

I will start by saying that I am not a multihull guy. But looking at the video of Macif on front page, if you want to foil, just go play multihulls. Monohulls just look awkward trying to copy them. Foils work with the multi platform structure, they don’t with a mono structure.

i will stick my neck out and say that using foils for RM and reaping the benefits of reduced weight/WSA is the natural limit of benefits for a mono.

They only look awkward right now because they are not allowed to use T Rudders. Once this is changed, they will fly as smooth as Macif most likely.

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On 9/27/2018 at 9:51 AM, 3to1 said:

then why do Ti bike frames out last steel (and obviously put aluminum ones to shame regarding fatigue)?

Steal corrodes and aluminium does also, and is 1/3 of the strength. Titanium will not corrode in a salt water environment.

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5 hours ago, dachopper said:

Titanium will not corrode in a salt water environment.

That's why god uses it to make beaches.

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8 hours ago, Rasputin22 said:

 

That’s pretty nasty. I hope the pilots were smart enough to pull power and slow to minimum IAS.

The only real way to evaluate these sort of modes is through frequency response testing which can be done in several different ways. I’d be less concerned with the keel than the foils.

In terms of hull shape, I would go for the minimum beam and hull required to allow for a reasonable lift off point. This reduces drag upwind, which can be critical after rounding the horn, and potentially reduces the overall weight of the hull.

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4 hours ago, samc99us said:

In terms of hull shape, I would go for the minimum beam and hull required to allow for a reasonable lift off point. This reduces drag upwind, which can be critical after rounding the horn, and potentially reduces the overall weight of the hull.

They went that way with the DSS-equipped Mini 6.50 a while back - it flopped so I guess it's important to work through the numbers to get the right balance of form stability and weight saving, and I imagine it varies with the size of the boat.  Insufficient form stablity could limit the boat's ability to get to lift-off speed.

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4 minutes ago, DickDastardly said:

They went that way with the DSS-equipped Mini 6.50 a while back - it flopped so I guess it's important to work through the numbers to get the right balance of form stability and weight saving, and I imagine it varies with the size of the boat.  Insufficient form stablity could limit the boat's ability to get to lift-off speed.

That mini was restricted to the 3 meter beam rule which included foils, so shouldn't be written off so easily. The rule has changed allowing the 650 foilers you're starting to see now.

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11 minutes ago, r.finn said:

That mini was restricted to the 3 meter beam rule which included foils, so shouldn't be written off so easily. The rule has changed allowing the 650 foilers you're starting to see now.

Ah yes, good point.  So it would be good to see someone have another look at that boat to see if it can work under the new rules.  But, as I understood it, it didn't have the stability to easily get up to a speed where the DSS could then do its thang, may e a bigger foil could solve that issue but of course it'd be draggier at displacement speeds.  Maybe less of an issue with a bigger boat with a higher hull speed.

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13 hours ago, dachopper said:

Steal corrodes and aluminium does also, and is 1/3 of the strength. Titanium will not corrode in a salt water environment.

 it's almost always metal fatigue or bad crashes that doom a bike frame, rarely corrosion.

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1 hour ago, DickDastardly said:

Ah yes, good point.  So it would be good to see someone have another look at that boat to see if it can work under the new rules.  But, as I understood it, it didn't have the stability to easily get up to a speed where the DSS could then do its thang, may e a bigger foil could solve that issue but of course it'd be draggier at displacement speeds.  Maybe less of an issue with a bigger boat with a higher hull speed.

I remember reading pretty much exactly that. Catch 22, it was too tender to get up to speed to gain stability....

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Not exactly true - this was designed for the Minitransat, so uphill wasn't an issue, but being quick downhill and in the light airs was what mattered.

So yes, was lacking grunt upwind but was very quick indeed downhill on the few trials that it did against the then current crop.  Would have done very nicely that year but funds and all the usual parked it up.

Now the total beam issue has been revised would be a great platform for new foils - its the lightest mini of any of them, will always be quick in the light stuff, and can get all the stability it needs now.   Add in the same foils I did for the SeaAir Mini and be off like the proverbial....but got improved foil configs now anyway that would really set it on fire.

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Where is the boat now Hugh?

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1 hour ago, DtM said:

Where is the boat now Hugh?

Near La Rochelle.

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7 hours ago, DickDastardly said:

They went that way with the DSS-equipped Mini 6.50 a while back - it flopped so I guess it's important to work through the numbers to get the right balance of form stability and weight saving, and I imagine it varies with the size of the boat.  Insufficient form stablity could limit the boat's ability to get to lift-off speed.

I think we are saying the same thing effectively. With all designs there are compromises. What I'm curious to see is how the latest generation of foilers go upwind compared with more conventional IMOCA's. Maybe after the boats are all launched and changes are limited VPLP will publish an article or two on the tradeoffs between foil design, hull form stability, keel incline angle etc.

My only real experience in this realm is on multihulls, where I have a somewhat unique position of being able to sail two boats with different hull shapes but near identical foil packages back to back. The more modern hull shape has additional buoyancy aft and a planning friendly hull so its more forgiving when down speed and easier to get up foiling initially. Once on foils both boats are about the same. Upwind the older style skinny hull works pretty freaking nicely; its going to be interesting to compare the two head to head in racing conditions. One of the big difference here vs. the IMOCA is we have lifting winglets on the rudders, so some of the hull form can be compensated for with additional winglet lift. Right now I suspect the new HB etc. will have pretty fat transoms to compensate for lack of foil generated lift aft.

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The IMOCA class itself has continuously made new boat specs more robust while grandfathering older hulls to keep them within the realm of some competitiveness with new boats. You're never going to see a bigger one edition generational shift than last and this edition - the class isn't going to overnight introduce T rudders and allow two foils in the water. 

The mini prototypes thus far with foils have been plagued by... fundamentally heavy boats equipped with foils - mainly because the builders are learning on the job/experimenting on both design & production and the learning curve is steep. I'm waiting for the Pogo 3 foiler that's coming out next year - a seasoned production builder using an existing sandwich platform + replacing glass with carbon & putting together a foiling package with VPLP has a highest chance of success. 

Arkema 3 was pushing too many design/production frontiers all at once. Scow bow, foil, wing sails, tilting keel, recyclable resin - it came out significantly heavier than was intended in the design. All things considered its first season was not bad at all. 2018 is a transition season so the results don't translate very well - but #865 (formerly Ian Lipinski's Griffon) under a diff skipper is still absolutely killing it in the prototype rankings. Arkema 3 (#900) is... consistently mediocre. 

 

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I will be interested to see how the new boats go upwind compared to a Volvo 65 rather than an existing IMOCA. I admit that my interest is in the next Volvo (or whatever it will be called), where upwind performance, especially in the light stuff is critical. 

The latest IMOCA look great on a reach in big breeze, but the rest of the time HB looked very average. Just look at the last Fastnet race.

If they don’t improve all round performance in the crewed configuration, you might see VO65s with youngsters on board sailing passed in that light stuff you get drifting into the finish

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On 10/3/2018 at 5:50 PM, trimfast said:

They only look awkward right now because they are not allowed to use T Rudders. Once this is changed, they will fly as smooth as Macif most likely.

They will look even less awkward when they are allowed two hulls! ;)

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6 hours ago, Chimp too said:

I will be interested to see how the new boats go upwind compared to a Volvo 65 rather than an existing IMOCA. I admit that my interest is in the next Volvo (or whatever it will be called), where upwind performance, especially in the light stuff is critical. 

The latest IMOCA look great on a reach in big breeze, but the rest of the time HB looked very average. Just look at the last Fastnet race.

If they don’t improve all round performance in the crewed configuration, you might see VO65s with youngsters on board sailing passed in that light stuff you get drifting into the finish

a VO65 probably would drop most if not all these 60's uphill in light air.

if I remember correctly, I saw a bit of footage of Hugo Boss going up wind in about 15 knots after rounding the Horn, looked like the transom was trying to plow a furrow and the bow looked to be riding too high while going rather slow. the overall impression was rather ugly. I can't remember if the existing foil was to leeward, but I think it might have been.

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6 hours ago, Chimp too said:

I will be interested to see how the new boats go upwind compared to a Volvo 65 rather than an existing IMOCA.

Best guide was the 2017 Fastnet. HB was the only foiler from memory and soundly belted by the non foilers. The VO65's murdered the 60's up hill.

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It is crazy to suggest that these super high powered boats should be multihulls.

They would be falling over all round the world. And I own and sail a multi.

Perhaps T rudder foils in the older boats may balance the playing field?

I suspect that the keel ventilation all the way down to the bulb is deliberate to reduce drag and keel lift. 

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Given how close to full foiling they are now, the time has come to allow T's on the rudders. If nothing else it will certainly provide pitch stability and ease the slamming and speed variations. 

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The problem with T rudders in these is that the skippers all like the kick up systems for if they hit something. Kick up a T rudder and the tip would come off. Only solution is to retract the windward one vertically. But hit something and your race is over as you then turn back into a hobby horse.

 I am also not suggesting that IMOCA turn multi, only that foiling monohulls is not a natural progression. If you want to foil a multi is the obvious starting platform. The same goes for the new AC75.

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With foiling monos are the boundaries between multi and mono becoming blurred? If you look at the latest imoca bow on with both foils extended ?

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16 minutes ago, Chimp too said:

The problem with T rudders in these is that the skippers all like the kick up systems for if they hit something. Kick up a T rudder and the tip would come off. Only solution is to retract the windward one vertically. But hit something and your race is over as you then turn back into a hobby horse.

 I am also not suggesting that IMOCA turn multi, only that foiling monohulls is not a natural progression. If you want to foil a multi is the obvious starting platform. The same goes for the new AC75.

A possible solution would be to have the T foil articulated so it stayed parallel to the water surface during a kick-up. 

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9 hours ago, Chimp too said:

The problem with T rudders in these is that the skippers all like the kick up systems for if they hit something. Kick up a T rudder and the tip would come off. Only solution is to retract the windward one vertically. But hit something and your race is over as you then turn back into a hobby horse.

 I am also not suggesting that IMOCA turn multi, only that foiling monohulls is not a natural progression. If you want to foil a multi is the obvious starting platform. The same goes for the new AC75.

 

I think you might be conflating trimaran/catamaran foiling with monohull foiling? 

In the multihulls, they're trading that form stability for dynamic stability & reducing drag. In the monohulls, they're not giving up righting moment from the keel & form stability - but supplementing additional righting moment with dynamic stability while reducing drag. 

I don't think one is more "natural" than the other - the difference is just the difference in how the forces are interacting. In the multihull scene, it is like balancing an eraser on two toothpicks on your palms. With the IMOCAs, one of the toothpicks is already in your finger and the other toothpick is on your palm resisting. 

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9 hours ago, oioi said:

With foiling monos are the boundaries between multi and mono becoming blurred? If you look at the latest imoca bow on with both foils extended ?

No

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On 10/4/2018 at 9:54 AM, 3to1 said:

 it's almost always metal fatigue or bad crashes that doom a bike frame, rarely corrosion.

I guess it depends where u live, how much you take care of the bike etc... I'd be voting for solid titanium for the keel structure, should be coming down in price in a couple years time with the 3d printing capabilities.

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Alpinefoil are using a solid titanium fuselage, on their kitesurfing kit. I can tell you its about 70% the size of the heat treated aluminium version but has the same strength....quite a reduction  in wetted  area. 

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On 10/3/2018 at 5:41 PM, samc99us said:

In terms of hull shape, I would go for the minimum beam and hull required to allow for a reasonable lift off point. This reduces drag upwind, which can be critical after rounding the horn, and potentially reduces the overall weight of the hull.

Not weight, windage.

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3 hours ago, jhc said:

Not weight, windage.

both, which was mentioned.

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14 hours ago, Remote Control said:

Didn’t Safran loose 2 titanium keels?

Just one, right after the start of VG 2012, while leading. Yann Elies raced that boat with a new keel in 2016. 

In the 2012 VG a carbon keel and a steel keel also broke off. Just wasn’t a good year for keels. Hence the one-design steel keels now. 

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2 hours ago, Roleur said:

Just one, right after the start of VG 2012, while leading. Yann Elies raced that boat with a new keel in 2016. 

In the 2012 VG a carbon keel and a steel keel also broke off. Just wasn’t a good year for keels. Hence the one-design steel keels now. 

Some are obsessing about materials and overlooking design and fabrication. 

Titanium bolts can be lighter than steel, but it is less forgiving of shear and you need to be extremely cautious and lube it up liberally and torque carefully. 

Not worth the risk IMO and there are better places to save the weight of a gallon of water. 

 

Folks were talking about fatigue above as if simple material changes solves problems. Continuing the bicycle frame analogy?

When we started on steel lugged frames fatigue was not a thing, because cromoly steel was extremely forgiving of high cycle fatigue - the limitation of how light you wanted your frame as diameter of the tubing was narrowed the frame became soft like a wet noodle. 

Then ppl started experimenting with 6000 and 7000 aluminium alloy frames (and before Giant figured out oil hydroforming) - American and EU builders were learning tough lessons. Make the diameter of the tubing larger to resist high cycle fatigue (which kills aluminium tubing), but then the frame got heavier and the ride quality was jarring. 

Then when the Soviets started selling titanium to the outside world in the 90s, besides learning how to weld it, the same lesson re titanium - diameter needed to be larger than steel, but narrower than aluminium, so in certain sizes you could end up with a light frame that was strong like steel but not harsh like aluminium. 

All this was before composite became mature and made titanium and steel novelty frames. 

What I'm trying to say is... you can build a keel out of almost anything. Provided the engineering challenges is appropriately understood, the balancing priorities done appropriately and manufacturing and installation and cared for appropriately. 

Seriously Hervé Devaux Structures have published in industry publications in the subject of flutter 5 years ago. Hydroem has been building imoca keel systems as long as the class has been around. 

Is it possible they're all missing something and a keel would fall off? Possible but it is less likely in an era where one design keel systems and mast have fixed parameters so the extreme aren't being pushed on the keel. Certainly they're not missing something so obvious amateur engineers who say titanium solves everything will think of. 

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You could combine a titanium core, with carbon fiber on the outside...... They are quite compatible, and you think would perform much better...

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3 hours ago, Miffy said:

Some are obsessing about materials and overlooking design and fabrication. 

Titanium bolts can be lighter than steel, but it is less forgiving of shear and you need to be extremely cautious and lube it up liberally and torque carefully. 

Not worth the risk IMO and there are better places to save the weight of a gallon of water. 

 

Folks were talking about fatigue above as if simple material changes solves problems. Continuing the bicycle frame analogy?

When we started on steel lugged frames fatigue was not a thing, because cromoly steel was extremely forgiving of high cycle fatigue - the limitation of how light you wanted your frame as diameter of the tubing was narrowed the frame became soft like a wet noodle. 

Then ppl started experimenting with 6000 and 7000 aluminium alloy frames (and before Giant figured out oil hydroforming) - American and EU builders were learning tough lessons. Make the diameter of the tubing larger to resist high cycle fatigue (which kills aluminium tubing), but then the frame got heavier and the ride quality was jarring. 

Then when the Soviets started selling titanium to the outside world in the 90s, besides learning how to weld it, the same lesson re titanium - diameter needed to be larger than steel, but narrower than aluminium, so in certain sizes you could end up with a light frame that was strong like steel but not harsh like aluminium. 

All this was before composite became mature and made titanium and steel novelty frames. 

What I'm trying to say is... you can build a keel out of almost anything. Provided the engineering challenges is appropriately understood, the balancing priorities done appropriately and manufacturing and installation and cared for appropriately. 

Seriously Hervé Devaux Structures have published in industry publications in the subject of flutter 5 years ago. Hydroem has been building imoca keel systems as long as the class has been around. 

Is it possible they're all missing something and a keel would fall off? Possible but it is less likely in an era where one design keel systems and mast have fixed parameters so the extreme aren't being pushed on the keel. Certainly they're not missing something so obvious amateur engineers who say titanium solves everything will think of. 

like the majority of scenarios out there, it's at least as important in how any material is used, than just simply the material itself.

painstaking attention to DETAIL from design concept all the way to final installation is key, just like strict maintenance. that being said, even though these are extreme racing machines, I'd think that relying heavily on steel would be the most logical starting point for the keel strut, most of the system's components, right down to most bolts and fasteners.

imo, the 65 pound weight penalty you threw out there would be more than acceptable if it means a net increase in overall keel/systems dependability. 

 

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The question is more of... why would anyone be obsessing at trying to reduce  keel systems weight when it is already one design. Spend the 250,000 euros on optimizing foils instead of replacing a keel systems that isn't the problem. 

There's an imagined keel problem and somehow the imagined solution is "more exotic weight saving materials" 

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just curious, so the one-design keel systems as is on these things are in fact good enough for their intended purpose then? 

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Hervé Devaux Structures and Hydroem are still involved in IMOCA - when something happens like a boat hitting something, they get called. Vincent Riou was the imoca skipper heading the technical committee back in 2008 that got the process of one design keels started. The imoca class is fundamentally owner and skipper driven. So I'd say if there were issues, skippers wouldn't be risking their life foiling on them.

None of the foilers that went around the world have lost their keels or abandoned due to keel damage. There were 7 foiling boats in the last edition, only 2 abandoned. The historical abandonment rate is 45%. - last edition was 38% abandonments. 

The more recent imocas that have had keel issues? 

Safran I, Beyou's Maître CoQ ---> which became Davis' Initiatives-Heart. Virbac Paprec 3 which became Hugo Boss then Bastide-Otio. They were all running non-one design keels fitted before the 2011 regs came out.

Beyou hit something, and was using a carbon keel that was fitted while the boat was Banque populiare. The boat has since been refitted and now has the one design keel system. PRB hit something - so I'm not sure that counts. 

The results speak for themselves - could the new imocas have keel issues? Yes. But they're not failing unexpectedly and the one design has contributed to future reliability because if one boat shows unexpected fatigue or issues - the designer and manufacturers are  the same and will share the exp.
 

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10 hours ago, 3to1 said:

just curious, so the one-design keel systems as is on these things are in fact good enough for their intended purpose then? 

Yes, Obviously they are....

The query I had originally posted referred to the overall suitability of the O-D keel system, now that the boats have gone foiling; the performance has leaped, and the loads, paricularly those peak dynamic shock loads, will be significantly greater.

The capacity to torture the foil from positive lift near the keel root through keel pin incline, but negative lift out at the bulb end of the fin by playing with bulb COG positioning, increasing the available RM is the one scenario that the top design studios must have explored or at least dreamt of, particularly following the AC wing development. Such wing control trickery, which in itself is still debated, can only ferment parallel thinking in smart brains in similar fields.

The desire to eek out all the available gains by a designer, and trick the foil into case loads that may not have been considered at its original design conception, remains a possibility.

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The OD keel fin is not supplied. The design package is. Teams can toy with incline angle etc and then hadecto make sure that the OD Cariboni can’t mechanism and lock pin fit as well as their own bulb. Metal choice is limited and must go for the expensive option ( can’t remember the metal off the top of my head, but not the most sensible choice really, as it dies corrode if exposed, and is very expensive for properties).

The lock pin is very agricultural and only allows keel to be locked on centre line for if there is an issue with the single ram. Wasn’t a Cariboni design.

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On 10/5/2018 at 2:10 AM, Chimp too said:

 I am also not suggesting that IMOCA turn multi, only that foiling monohulls is not a natural progression. If you want to foil a multi is the obvious starting platform. The same goes for the new AC75.

I think ocean racing will go back to multis like the ORMA 60s.  Multis inherently have the beam that giant foils, deck spreaders, and canting keels seek to achieve artificially.  Once you add all that stuff to a mono, it costs more than a multi and is still slower.

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4 hours ago, eastern motors said:

I think ocean racing will go back to multis like the ORMA 60s.  Multis inherently have the beam that giant foils, deck spreaders, and canting keels seek to achieve artificially.  Once you add all that stuff to a mono, it costs more than a multi and is still slower.

It's certainly going to be interesting in the next couple of years with the foiling Ultimes doing the Route de Rhum and presumably some going for the RTW record maybe the season after. And then there is that new Sailing GP thing on an improved AC50s with better foil control. These boats may, I would say will, define a new level of speed and reliability for  inshore and offshore foiling that will be a big challenge to the elite mono classes.  But maybe not. The ORMAS all flipped and you seem to need an Ultime sized tri to reliably not capsize (though BP IX did prove this wrong!) , so perhaps at the 60 foot scale a semi-foiling mono that rights itself makes more sense. It will be fascinating.

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7 hours ago, eastern motors said:

I think ocean racing will go back to multis like the ORMA 60s.  Multis inherently have the beam that giant foils, deck spreaders, and canting keels seek to achieve artificially.  Once you add all that stuff to a mono, it costs more than a multi and is still slower.

since when is it all about raw speed? the Mod 70's, for example, were killer boats, they didn't instigate any kind of shift away from monos. apples and oranges.

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1 hour ago, 3to1 said:

since when is it all about raw speed? the Mod 70's, for example, ARE killer boats, they didn't instigate any kind of shift away from monos. apples and oranges.

FIFY

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The VG has allways been on Monos (IMOCAs) .

The reason they became the "prime" ocean racing class has more to do with the demise of open 60s (due mainly to one catastrophic route du rhum) and mod70 (that OD class never really took off) than multis/monos.

But now the ultim class is taking the slot for multis somehow

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I am not suggesting that IMOCA goes multihull. That will never and should never happen. What I am saying is that IMOCA, or who ever runs a monohull class should manage them as a monohull. I think that allowing foils that do more than generate side force or RM is a slippery slope. Foils have become silly expensive and I don’t think that the development has even really got started properly.

take any monohull that takes 40,000 hours to build, needs foils that cost €1m including tooling (won’t be used twice as second set will be development of first), and you aren’t going to get a lot of change out of €10m for a build (sailing). That doesn’t sound sustainable to me.

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14 hours ago, Foiling Optimist said:

It's certainly going to be interesting in the next couple of years with the foiling Ultimes doing the Route de Rhum and presumably some going for the RTW record maybe the season after. And then there is that new Sailing GP thing on an improved AC50s with better foil control. These boats may, I would say will, define a new level of speed and reliability for  inshore and offshore foiling that will be a big challenge to the elite mono classes.  But maybe not. The ORMAS all flipped and you seem to need an Ultime sized tri to reliably not capsize (though BP IX did prove this wrong!) , so perhaps at the 60 foot scale a semi-foiling mono that rights itself makes more sense. It will be fascinating.

FYI: Francis Joyon's last IDEC Maxi-Tri capsized shortly after the start of her attempt on the solo west to east transatlantic record in 2011.
http://www.thedailysail.com/offshore/11/59664/0/francis-joyon-and-hurricane-irene

199810240_IDECCapsized.jpg.a81fea63b4aefe8c1424efa838ec6265.jpg

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IMOCAs are getting more expensive, but multi foilers are even more expensive and this is before they're subjected to any organized safety rules. The rigs are significantly more expensive and their safe operating season is much more narrow. 

There's a very Anglo attitude that things must be either or. Let's just enjoy the IMOCA for what they are. 

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22 minutes ago, Miffy said:

IMOCAs are getting more expensive, but multi foilers are even more expensive and this is before they're subjected to any organized safety rules. The rigs are significantly more expensive and their safe operating season is much more narrow. 

There's a very Anglo attitude that things must be either or. Let's just enjoy the IMOCA for what they are. 

I don't think you need a "multi foiler" to beat Charal.  A MOD70 would do. 

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