A-Class foiling sailors

[flyinggorilla 40]

Hi A-Class foilers, 

I start this thread to have a forum for some basic how-to exchange on foiling A-Class catamarans. I am proud new owner of a DNA F1x catamaran (for single handed sailing) and also sail a Whisper catamaran (works best with crew) for the third season. I am a weekend recreational club-sailor, who loves cool technology and nature at the same time. However, I still have to figure out if and when there is ever enough time to prep and sail the first club regatta. Hence you will find my priorities more on how to mount a gopro, rather then regatta starting-line tactics ;-)

Just to get this thread kicked-off, here is a video from my first time sailing with the DNA F1x. I have to say that I was very pleased with the smooth and easy boat handling, the clean deck, the powerful boomless sail, and the stable flight in little winds. And of course the speed. I hit 20kts boat speed on my first day at low winds (18kts speed were captured on gopro) - and I am still at the beginning of learning the boat handling and trimming. cool! 

 FG

[flyinggorilla 40]

A-Class DNA F1x vs. Whisper catamaran - first impressions

 

 

• Alone or with Crew
  • A-Class cats are by class-definition single-handed catamarans. Also the mast is tuned for my weight and could not withstand two people.
  • Whisper has two trapeze-lines and is best balanced with two people. It can be sailed single-handed too - but find it tricky to get enough upwind VMG one the foils with not enough weight. So taking out friends, family and kids are fantastic with the whisper. I capsized frequently, but never had an ugly nosedive like with my Nacra F16 I had before as the thin hulls - the wavepiercers -  go so smoothly through the water and dont stop the boat. In fact, I is now much easier to get the family - kids to wife - onto the foiling catamaran than on the F16 classic cat, as the foiling catamaran behaves in all situations more stable and is easier to upright and get back on the boat.
• Rigging the F1x is simpler: 
  • No halyard. You simply push the sail up till it hooks. Only two battens to mount when hoisting the sail.
  • No rig tensioning needed. Also less work.
  • No jib. So less work.
• Z-Foils insert from top and fully removable.
  • So it is much easier on land to quickly pull the boat over to the side for whatever mast maintenance reason.
  • Or to put hullkote on the foils or sand them with 800 paper (this foil tuning is on my todo list for both boats - I am curious how much I can notice a speed difference). Unmounting the T-foils on the whisper always requires to remove the rudder-mounts entirely so I can tilt the boat up.
  • Oh, another advantage of removable foils is to easier get the boat on-off the trolley – especially the 4-wheel trolley I use. With the whisper I need to get into 60cm deep water so the trolley would be deep enough under the boat to not hit the t-foils when moving the boat off the trolley.
  • The Z-foils cannot fly as high as the whisper, so in waves (that I don’t have at my lake) the whisper might be easier to keep balanced above thee waves. So about 30-40cm water to hull for the F1x, vs. whisper approx. 50-80cm water to hull
  • Whispers T-foils have flaps for easier flight control, but I find with the tradeoff of less VMG upwind. Yes, one should heel backwards like on the moth, but I can do this only in excellent wind conditions.
• Boomless sail on the F1x – so good for not bumping the head – and the sail better shaped, deeper, giving quickly power starting with low winds and keeping it up at speed. This triggered me thinking about how I could better tune the battens and sail shape of the Whispers for more power quicker..
• 75kg entire boat plus rig! That’s at about 35kg less than the Whisper, which is also super-lightweight. Both can be uprighted single-handed.
• The F1x is clearly tuned for racing - and for speed. Small things, like a line to keep the mast rotated out even at low winds, adjustable foil rake that steers both foils in sync, and adjustable rudder rake that steers both rudders in sync. And lots of aerodynamics improvements. Really cool. The Whisper is designed for fun foiling - for which i love it.
• The DNA F1x setup is super clean, the traveler sheet is inside, the mainsheet goes into the middle of the trampoline into a wheel system that speed/force-transforms to a thin dyneema mainsheet to the sail. Super clever andno longer dangling sheets in the water.

FG

 

[flyinggorilla 40]

Mounting a GoPro on an A-Class catamaran

My former Nacra F16 and my Whisper catamaran have a gennaker pole, so mounting a GoPro there was obvious. But where to mount a GoPro on an A-Class catamaran that doesnt have a gennaker pole? I didnt like the idea to use suction on the hull (have seen to many youtoube videos where the GoPro comes off), so I figured the furthest out on the boat are the forestays. Since there is no standard GoPro mount that fitted the need for that location, I 3D printed one. I assume this fits on many A-Class cats, so hope that helps.

https://www.thingiverse.com/thing:3170230

[SCARECROW 735]

that mount is cool, good job

[F18 Sailor 326]

I'm not sure how well faired the DNA foils or the Whisper foils are from the factory, so how much you will gain is a bit variable. Generally, poorly faired foils result in less than stellar foiling control as you get ventilation and cavitation much sooner than the design parameters.

[martin 'hoff 1,002]

2 hours ago, samc99us said:

poorly faired foils result in

I've heard theories around z-shaped foils, saying that some surfaces should be smooth and others rough to improve earlier (low speed) foiling, with perhaps some tradeoffs with ventilation at top speeds.

All late night, dive bar conversation. Very cloak and dagger. You can tell I wasn't told the actual recipe by the fact I'm alive.

[martin 'hoff 1,002]

18 hours ago, flyinggorilla said:

Mounting a GoPro on an A-Class catamaran

Cool! Are those bungees/elastics? The video -- which is amazingly cool -- seems to show the camera moving towards and away from the boat. Combined with the wide angle, this makes the bows "change shape". It's all because of the sudden acceleration, so I'm green with envy :-) -- Tighter mount, non-elastic lines might help.

And I love how the mast says "MAST". ISO 9001 right there.

 

 

[Erwankerauzen 83]

Thkx for the video,

It is interesting to notice (If I noticed correctly) that the leeward foil has not the same angle compared to the vertical than the windward foil.

Has anybody noticed the same observation ?

Cheers

 

 

[flyinggorilla 40]

7 hours ago, samc99us said:

I'm not sure how well faired the DNA foils or the Whisper foils are from the factory, so how much you will gain is a bit variable. Generally, poorly faired foils result in less than stellar foiling control as you get ventilation and cavitation much sooner than the design parameters.

My DNA foils have been color coated. Surface is glossy. However, DNA recommends to sand and/or hullkote the foils in general.

[flyinggorilla 40]

4 hours ago, martin.langhoff said:

Cool! Are those bungees/elastics? The video -- which is amazingly cool -- seems to show the camera moving towards and away from the boat. Combined with the wide angle, this makes the bows "change shape". It's all because of the sudden acceleration, so I'm green with envy :-) -- Tighter mount, non-elastic lines might help.

And I love how the mast says "MAST". ISO 9001 right there.

 

 

Exactly. I have the same conclusions. The lower lines have some rubber band attached. I will remove those and only go with my 1.7mm leech line, that does not flex. That should reduce the shaking a bit.  

[flyinggorilla 40]

3 hours ago, Erwankerauzen said:

Thkx for the video,

It is interesting to notice (If I noticed correctly) that the leeward foil has not the same angle compared to the vertical than the windward foil.

Has anybody noticed the same observation ?

Cheers

 

 

Nope, that is just some gopro wide-angle distortion. The foils are kept pretty tight in its shafts. The angle can only be adjusted in forward/backward direction, but not sideways.

[Defy 52]

You have a well tuned 3d printer looks great.

[flyinggorilla 40]

What to do in a storm?

When the foen storm with 30+ knots came in, I quickly changed from "sailing" the A-Cat to "hanging-on" the A-Cat. I still capsized four times, yes I tried to sail, but the waves and wind just played too hard rodeo with me. I am wondering if you guys have hints and tips how to better deal with such situations. After uprighting the boat the last time I ended up "riding" the boat at 2-3 knots boat speed with the bows against the waves, cunningham pulled, traveler furthest out, main-sheet lose. What else could I do to "hang through the storm". I figured after 20min getting through the worst that maybe getting closer to the shore at the right spot could have had smaller waves, and as such safer "sailing". So I realized I should have tried to get closer to the shore much earlier. Yet there is another risk, as capsizing close to the shore with mostly cross-shore winds is something that I dont want either, because the risk of hitting something and causing a real damage is just much bigger. At some point I wanted to sail through it, pulled not only cunningham but also rotated the mast completely in (meaning no rotation) to have minimum power., while opening main-sheet and traveler. After the storm - and after 4 capsizes - i realized that 4 battens were broken. Not sure whether the combo of no-mast-rotation plus open traveler/main-sheet was the issue or one of the capsizes or both. Clearly next time I get into a storm I will have the mast-rotation completely open. Sailing with broken battens works more poorly than I had guessed.

After all, I think I managed through my first storm, broken battens isnt the worst, but clearly I want to do better next time. Such foen storms are new to me, very rare at my lake, and as such I am curious what additionally I could have done to get better through such storms. 

Finally, the parts hitting 21knots downwind - the combo of silence and speed - gave me a big *grin*, compensating for the rest. Very challenging with winds turning 90-180 degrees, but a great experience of nature and sailing.

Best,

FG

[Paolo Peruzzi 0]

Hey Bernd, couldn’t you pay a pro a-class sailor for coaching from your petty cash? That would help you the most...

[flyinggorilla 40]

3 hours ago, Bimmer said:

Hey Bernd, couldn’t you pay a pro a-class sailor for coaching from your petty cash? That would help you the most...

For sure that makes sense and it's clearly on my todo list for next season. However, training "handling stormy situations" is likely not on the standard coaching program. So sharing some tips and lessons learnt online can help others too.

FG

[SCARECROW 735]

Fact is if you've managed to keep a modern A in anything resembling one piece in 30+ knots you're doing bloody well.

 

[Boink 838]

My tip would be to rewatch your videos focusing on your stance - curiously you are giving away heaps of RM with both having a high hook position and and almost sitting stance.

Your centre of mass is at your sternum (bottom centre of your rib cage) yet with your sitting type stance it is little further outboard than your hips.

Contrast that stance to the top guys - Glen Ashby in particular; you are giving away heaps of RM which may just save you an occasional capsize, certainly need to learn to drive and control the boat rather than have it control and drive you. His stance is feakishly low and utterly upright. Study what they do, before you develop soft and bad habits.

Head back, Shoulders back, straighten those legs as much as possible. It will feel uncomfortable and unnatural, and the effort required is much greater - but you will never get max performance unless you train yourself to do this. Play squash over winter. Fast sheet play with no wrapping of that sheet round your hand, whilst steering smoothly.

Definitely get some coaching - either in a group or one on one. 

But nice work on your early outings. Beautiful boat. Keep the faith. If it was easy, everyone would do it....... 25kts soon enough

[F18 Sailor 326]

In 30 kts+, or any condition beyond your control, your best bet would have been to drop the main on the water and re-hoist later. I have done this on the F18 in a situation where we felt gusts would exceed 40 kts.

Boink,

  You are certainly right upwind, but downwind take a look at Mischa. Lower on the wire sure, but super wide and stable stance.

 

[Lost in Translation 61]

Nice sailing.  Re a short storm, I've always heard the best approach is to drop the traveller and feather into the storm with no cunningham on and let the breeze pass.  Sit on the main beam and wait for the intensity to pass.

[flyinggorilla 40]

17 hours ago, Boink said:

My tip would be to rewatch your videos focusing on your stance - curiously you are giving away heaps of RM with both having a high hook position and and almost sitting stance.

Your centre of mass is at your sternum (bottom centre of your rib cage) yet with your sitting type stance it is little further outboard than your hips.

Contrast that stance to the top guys - Glen Ashby in particular; you are giving away heaps of RM which may just save you an occasional capsize, certainly need to learn to drive and control the boat rather than have it control and drive you. His stance is feakishly low and utterly upright. Study what they do, before you develop soft and bad habits.

Head back, Shoulders back, straighten those legs as much as possible. It will feel uncomfortable and unnatural, and the effort required is much greater - but you will never get max performance unless you train yourself to do this. Play squash over winter. Fast sheet play with no wrapping of that sheet round your hand, whilst steering smoothly.

Definitely get some coaching - either in a group or one on one. 

But nice work on your early outings. Beautiful boat. Keep the faith. If it was easy, everyone would do it....... 25kts soon enough

Thanks, that are great tips, really helpful. That's motivating and I will absolutely train the stance at better wind conditions - I agree, the difference to the pro's is too obvious ;-). Two of my capsizes on downwind course were related to wind coming within seconds form the opposite direction (north wind flipped to south foen wind to my very surprise), so I guess only a better reading of the water and getting quicker back onto the boat could prevent that capsize. Ah, and the tip on the sheet wrapping is interesting - do you use your tiller-hand to give/take additional sheet when you dont wrap?. I really look forward to get coaching next season. 

[flyinggorilla 40]

8 hours ago, Lost in Translation said:

Nice sailing.  Re a short storm, I've always heard the best approach is to drop the traveller and feather into the storm with no cunningham on and let the breeze pass.  Sit on the main beam and wait for the intensity to pass.

thanks, good tip. 

[Tornado_ALIVE 119]

As Sam said, drop the main in the storm situation.  It might be tricky taking the angle and vertical batten out though.

[A Class Sailor 175]

19 hours ago, Boink said:

My tip would be to rewatch your videos focusing on your stance - curiously you are giving away heaps of RM with both having a high hook position and and almost sitting stance

Do you sail an A? I doubt it, because this is how the top guys sail downwind.

or

The last photo is Glen Ashby who trapezes lower than anybody else. Most top guys are like Mischa in the top photo, or higher. Note the wide stance and bent legs.

Yes, flyinggorilla is maybe a little higher but that is a trend at the moment, because while you give away some righting moment, the boat is far easier to sail and push. Because most don't use adjustable trapezes because they want to keep things simple, the further back you go, the higher you trapeze due to simple geometry. The lower you are the harder it is to stay on the side of the boat. I know lots of sailors who tried adjustable systems to try sailing lower on the trapeze when back and who have now removed them. Bent legs, feet well apart and being slightly higher is the correct thing for most to do.

When watching the top guys, it seems to me that they are trapezing higher than they used to, except maybe for Glenn Ashby and I believe this is because it is harder to stay on the side. When you used to sail with a little heel, you could trapeze very low but now the boats are sailed flat or even heeled to windward a bit, it is much harder to stay on the side, so trapeze heights have gone up.

My advise to flyinggorilla is to stay high until you feel comfortable to go lower, but not to go too low. Keep you legs wide apart and don't worry about the bent legs.

[Tornado_ALIVE 119]

Trapping higher helps when you are a punter learning and this happens 

[Lars Schrøder d 13 18]

Storms - look up weather forecast and if necessary stay on shore;- ) else try to survive.

Traveller can be sensitive, so don't release further than 10-20 cm out from center, to keep the pressure on both foils.

Trapezing, some northern europeans try to go low.. it works well in a stable breeze, but can make life harder in less wind.

But your flying looks good on the videos, so keep up the good work. And that F1x is cool cool boat.

[Paolo Peruzzi 0]

Dear Bernd, what about you ask your questions also at the german forum?

http://vdac.okbb.de/portal.php

Then you can get personal appreciation and information from members which you can also call. Makes more fun than surfing in the anonymity. And with your financial possibilities, everybody would buy a second f1x as a spare boat in case of damage which could mean loosing months of the season

[Lars Schrøder d 13 18]

Dear Bimmer - you seem to have some kind of personal issues regarding flyinggorilla, maybe you could use the messaging system to communicate directly with him. Without hidding behind nicknames.

Best Lars

[Paolo Peruzzi 0]

1 hour ago, Lars Schrøder d 13 said:

Dear Bimmer - you seem to have some kind of personal issues regarding flyinggorilla, maybe you could use the messaging system to communicate directly with him. Without hidding behind nicknames.

Best Lars

Thanks for your attention Lars Schrøder but you gave the advice to check the weather forecast and i just wanted to give him also a valuable input 

[SCARECROW 735]

12 hours ago, Bimmer said:

And with your financial possibilities, everybody would buy a second f1x as a spare boat in case of damage which could mean loosing months of the season

Jealous much?  I thought "Tall Poppy Syndrome" was an Aussie thing.  I guess it happens all over.

[flyinggorilla 40]

Starting into the new season with the DNA F1x. Making progress on lower trapezing - just the lake is still realllly cold with 6 degrees celcius. ;-)

 

[flyinggorilla 40]

And here is one more, two days later, similar nice weather, similar cold water. Now peaking at above 20 knots boat speed. 

 

[CRAMER 0]

I have been messing around with a Gel Tec , Flyer Hull, which I self converted to an Exploder Z-5 boards and Non catridge Rudders. 

I am like the punter photo , only worse.  when i come out of the water, 

1. Go way to windward, dosing myself in the water. 

2. Momentum wants to pitch me foward. 

3. Boat wants to round up to windward. 

I have rudders at about 0 pitch , 

The dagger boards should be installed correctly, but a little sloppy, I had to keep filing the exit plate , so that the boards would go up an down.

My advise from A Cat community is to  get a new modern platform, which I agree. but I dont have the 17K to spend right now. 

any pointers, PLease, Please  .   

[Lost in Translation 61]

hi Cramer,

You have to ease to fly but as soon as you do fly, you need to trim on to keep from rolling to windward.  The boat accelerates and now the eased trim is really eased.  

Have you gotten Matthew to try the boat to rule out anything especially unique there?   

[F18 Sailor 326]

CRAMER,

   Many unknowns with your setup-board AoA, actual winglet AoA and rudder blade rake. How does the boat go to weather? You should have slight weather helm. Start with the mast at 4.8 degrees of rake or so, but that also depends on your sail and what breeze you're in. Bruce runs 3 degrees most of the time, but he is a bigger guy.

My converted Boyer Flyer is for sale at much less cost than a new platform, it has all the latest rigging on it, Z10's, big winglets on fully adjustable rudders and a reinforced beam. Boards are in the same location as the new boats. Only downside is its not quite as much hull volume as the new boats, but if you are less than 175lbs you will be just fine. Boat has finished in the top 10 in the competitive winter series with my less than fast fingers on the helm, so if you get tired of your boat, this one might be a good choice.

P.S-I also had to sand the board exits a lot, the eXploder factory ones don't really work with our hull shape. I then glassed the inside of my Z10's at the board exit to keep them from twisting in the trunks. Between that and the main beam reinforcement, the boat is faster than ever. I just happened to get a pretty good deal on a top flight AD3 so am making the switch in anticipation of the 2020 Worlds.

[flyinggorilla 40]

To better analyze how the pro's are tacking and jybing I created a super-slow motion video. Helped me a ton to improve this season, so I am sharing now with credits to the original sources.

https://youtu.be/02QSYXlbo40

 

[flyinggorilla 40]

Here is another "learning from the pros" series video. Mischa Heemskerk tacking in hi-res and super-slow-motion at the Dutch 4 Nations Cup 2020. Of course, Mischa won!

Thanks to the people who created the great source video allowing to create this slow-mo.

source: https://youtu.be/1NNyPFDdcVo

[Butenbremer 10]

7 hours ago, flyinggorilla said:

Here is another "learning from the pros" series video. Mischa Heemskerk tacking in hi-res and super-slow-motion at the Dutch 4 Nations Cup 2020. Of course, Mischa won!

Thanks to the people who created the great source video allowing to create this slow-mo.

source: https://youtu.be/1NNyPFDdcVo

Thanks for the effort FG!

Interesting to see Mischa throws the sheet on deck way before he even starts initiating the tack. And I cannot really see the main to open significantly. So does the F1x has a kind of cleat or is the resistance of the magic wheel system high enough to allow such thing? In my lesser mortal version of a tack with a random mainsheet system I have to get firm hold of the sheet until almost head to wind...

Any comments, in particular from the F1x fraction?

Oh, and mind the "new" windward hull is safely out of water before Mischa is even through the triangle, something one could train for sure:-)

 

[flyinggorilla 40]

10 minutes ago, Butenbremer said:

Interesting to see Mischa throws the sheet on deck way before he even starts initiating the tack. And I cannot really see the main to open significantly. So does the F1x has a kind of cleat or is the resistance of the magic wheel system high enough to allow such thing? In my lesser mortal version of a tack with a random mainsheet system I have to get firm hold of the sheet until almost head to wind...

Any comments, in particular from the F1x fraction?

 

 

I was wondering about that sheet thrown on deck too for a moment, but it's obviously not a good idea to lose hold of the sheet. So when you watch closely while Mischa is still trapezing then you can see the sheet just below the tiller extension. So you what happened is a few seconds prior to this video recording Mischa switched sheet from left hand to tiller-hand. So no magic cleat there ;-)

[Canhobie 5]

The idea of dropping the main in a storm seems like a really good idea.I have done this myself when returning to shore with a prevailing wind.The only concern I would have with doing it in a storm is how to collect the mainsail while it is coming down.It would seem to me to be a cluster Fuc.. to gather main and keep it on the boat.It would also be very tricky ( I would think ) to get the main hooked up again after stom passes,which would pretty much limit you to drifting downwind.The upside to all this is you would definitely survive the storm with minimal damage.

[F18 Sailor 326]

Not sure what dropping the main in a storm has to do with how to tack an A-Cat faster?

Some have added the deck cleat back to make tacking easier and sailing downwind in light air a bit easier.

[Canhobie 5]

I was replying to a post on this same thread from you,I guess it was back on Nov. 5 2018 where the original poster was talking about getting caught in a storm.Look back you will see.

[F18 Sailor 326]

8 minutes ago, Canhobie said:

I was replying to a post on this same thread from you,I guess it was back on Nov. 5 2018 where the original poster was talking about getting caught in a storm.Look back you will see.

Okay, pretty dated post and big thread drift. All good, definitely dropping the main if its a big squall can help.

What I'm looking for are more gybe sequences downwind...currently I walk forward, to about halfway between the shroud and the rear beam, pop the weather hull to get the boat off the foils then go for the gybe. There is probably a faster way, and one of the areas I struggle with is getting back on the wire.

[flyinggorilla 40]

23 hours ago, samc99us said:

What I'm looking for are more gybe sequences downwind...currently I walk forward, to about halfway between the shroud and the rear beam, pop the weather hull to get the boat off the foils then go for the gybe. There is probably a faster way, and one of the areas I struggle with is getting back on the wire.

that is the best gybing material I had found, put in slowmotion. let me know if there is helpful learning material i havent noticed yet. https://youtu.be/02QSYXlbo40 

[flyinggorilla 40]

This is my last slow-motion make based on the videos I had found so far. Mischa Heemskerks stunt on the A-Cat is too cool to not analyze a bit closer. What a boat handling. 

 

[SimonN 718]

On 11/11/2020 at 3:32 AM, Butenbremer said:

Interesting to see Mischa throws the sheet on deck way before he even starts initiating the tack.

For some reason I cannot watch the video but I am as sure as I can be that he doesn't let go of the sheet. He certainly doesn't have cleat. What I believe he would be doing is that some time before the tack, he takes the sheet in his tiller hand and then throws the tail into the boat so as to free his front hand. I believe that in the freeze frame of the video, I can see the tiller and mainsheet in his rear hand. He then grabs the handle and initiates the tack. I am not sure how he goes through the boat or gets out on the wire, because there are a few methods. Many have the mainsheet in the same hand as the tiller and use their free hand on the handle, slipping sheet through the hand as you move away from the centreline. However, a few like Stevie Brewin prefer to get the mainsheet into the front hand straight after the tack and get out on the wire without using the handle at all, just sliding their arse backwards over the edge and when the weight is on the wire, then use their legs to do the rest. This allows you to keep adjusting the sheet throughout the tack but it is way harder.

[WetnWild 62]

3 hours ago, SimonN said:

For some reason I cannot watch the video but I am as sure as I can be that he doesn't let go of the sheet. He certainly doesn't have cleat. What I believe he would be doing is that some time before the tack, he takes the sheet in his tiller hand and then throws the tail into the boat so as to free his front hand. I believe that in the freeze frame of the video, I can see the tiller and mainsheet in his rear hand. He then grabs the handle and initiates the tack. I am not sure how he goes through the boat or gets out on the wire, because there are a few methods. Many have the mainsheet in the same hand as the tiller and use their free hand on the handle, slipping sheet through the hand as you move away from the centreline. However, a few like Stevie Brewin prefer to get the mainsheet into the front hand straight after the tack and get out on the wire without using the handle at all, just sliding their arse backwards over the edge and when the weight is on the wire, then use their legs to do the rest. This allows you to keep adjusting the sheet throughout the tack but it is way harder.

Mmmm. He definitely throws the sheet on the deck from his forward hand while still out on the wire then grabs the handle. It’s in the 4 nations video using the blue boat. 
not a procedure fore mere mortals like myself. Maybe he gets in so fast and set up that only a little bit of ease happens. 

[Butenbremer 10]

5 hours ago, SimonN said:

For some reason I cannot watch the video but I am as sure as I can be that he doesn't let go of the sheet. He certainly doesn't have cleat. What I believe he would be doing is that some time before the tack, he takes the sheet in his tiller hand and then throws the tail into the boat so as to free his front hand. I believe that in the freeze frame of the video, I can see the tiller and mainsheet in his rear hand. He then grabs the handle and initiates the tack. I am not sure how he goes through the boat or gets out on the wire, because there are a few methods. Many have the mainsheet in the same hand as the tiller and use their free hand on the handle, slipping sheet through the hand as you move away from the centreline. However, a few like Stevie Brewin prefer to get the mainsheet into the front hand straight after the tack and get out on the wire without using the handle at all, just sliding their arse backwards over the edge and when the weight is on the wire, then use their legs to do the rest. This allows you to keep adjusting the sheet throughout the tack but it is way harder.

Hi Simon, thanks for setting this right, fully correct, yes, as FG also pointed out it is visible in the video Mischa changes sheet to tiller hand and throws the rest of sheet  with the other hand on deck, shame on me for overlooking this ;-)

Actually I also prefer the method with sheet on the tiller hand and pull with the forward hand on the trap handle to land on the tramp on my knees face forward for the dive through the sail-sheet triangle- not entirely unlike Mischa in the analysis

[SimonN 718]

So today I can see the video and Mischa does a version of what I suggested, with a really interesting twist. You can clearly see him pass the sheet from his front hand to his rear hand, but what is unusual is that he isn't holding the tiller extension at the time but has it tucked under his arm. You can then see him move his hand back onto the extension. He does that same trick on the new tack when he changes the sheet from one hand to the other. This "move" really is unique to Mischa, as I have spent too much time watching other top sailors and know they do not do that.

For a full analysis and to get your tacking better, you need to take the slow motion forward a bit more, because I would suggest that most sailors lose the most time from the moment the slow motion finishes to the point of being back to full speed. When not foiling, we are talking about losing a boat length or 2. When foiling, we can be looking at 50 metres lost in a tack. Same applies to gybes.

[WetnWild 62]

13 hours ago, SimonN said:

So today I can see the video and Mischa does a version of what I suggested, with a really interesting twist. You can clearly see him pass the sheet from his front hand to his rear hand, but what is unusual is that he isn't holding the tiller extension at the time but has it tucked under his arm. You can then see him move his hand back onto the extension. He does that same trick on the new tack when he changes the sheet from one hand to the other. This "move" really is unique to Mischa, as I have spent too much time watching other top sailors and know they do not do that.

For a full analysis and to get your tacking better, you need to take the slow motion forward a bit more, because I would suggest that most sailors lose the most time from the moment the slow motion finishes to the point of being back to full speed. When not foiling, we are talking about losing a boat length or 2. When foiling, we can be looking at 50 metres lost in a tack. Same applies to gybes.

Ah yes. Correct Simon. I first watched it on a phone and was mistaken. Big screen reveals all. Very cool with tiller arm tuck. Best boat handling outside GA. 

[maxstaylock 378]

Thanks for the slomo's, very useful, thanks, even for flat footed classic sailors.

+1 on making up some of the exit of tacks and gybes, hitting the wire and speed build parts?  It's where I feel slowest, I always hike, hook, push off while holding sheet, but would love to work on making it more contenderesque/mpsish.

[Butenbremer 10]

Looking on the slomo another thing that strucks me is the perfect kinetics: So you can see Mischa hits the deck almost horizontal on his knees, thus in sync with steering giving the boat another push through the tack. This is also the moment the new windward hull starts to lift off. At the moment the sail flips over, the windward hull is already entirely in the air and never again touches water. To me this is the equivalent of a dinghy roll tack.

Memo to myself: Work on it:-)

[SimonN 718]

A cautionary tale......

Yesterday, I had my first capsize for well over a year, and it was one of the biggest I have ever had in an A. Conditions were a bit unusual - 10-15 knots gusting 22 and 40 degree c temperatures, so it was like sailing in a hair dryer. Travelling upwind, one minute we were not foiling and then the boat was leaping out all over the place. I hooked into one puff and the boat was out of control. The others were doing over 22 knots steady and I was going noticeably faster. The bow was rising and the boat was also coming over on top of me. I still cannot work out exactly what happened but very, very suddenly I was heading forward and I hit the boat somewhere between the main beam and the forestay, landing on my forearm/elbow. I slid over the top of the deck and ended up in front of the main beam. During all of this, my helmet got ripped off (despite the strap being properly tightened), I lost my sunnies, and hat. The compass bracket was ripped off the main beam. Strangely, the compass itself came off the bracket and floated, so I could grab that but the bracket was gone.

I was in a world of hurt, particularly my arm which I couldn't really use. One of my team mates picked me up and I dropped him next to my boat, and he got it up and I limped home. Another team mate found my helmet, so in the end, I was down a  compass bracket and a pair of prescription sunnies. Remarkably, there are no dents in the boat.

A few lessons stand out. I am pretty sure that without a helmet, we would have had a pretty serious situation. Besides a bruised arm, I have some whiplash in my neck today. If I hadn't been sailing with a group, I am not sure what would have happened. I don't sail on my own, because I know people who have swum home after the boat has drifted away, but this has reinforced this. Maybe without friends, I wouldn't have been pushing so hard. So please wear a helmet, make sure it is properly done up and if you do sail alone, have a strategy planned for what happens if you cannot self rescue.

The other lessons are about how you sail the boat. First thing to note is that upwind is way more wild than downwind, even though downwind you are probably going 6 knots faster. On a well set up A, 26-7 knots downwind really is armchair sailing, once you have some experience. I wonder whether upwind will ever feel like that (I doubt it). Maybe what I should have done is to not foil in the big gusts, but the top guys are doing that and as that is who I am training with, I don't want to be left behind.

For me, the most interesting learning has been about foot loops and where to stand. Up until now, I have always foiled upwind with my rear foot in the front loop and a wide stance, because I felt I needed the foot in the loop for security. That didn't help me at all yesterday! What my tuning mates do is to walk the gunwale far more, so in the big gusts, they are trapezing level with the shrouds. With the mainsheet on hard, I now realise that this position is more locked in than being further back with a foot in a loop. Think about it - if the mainsheet is pulling you inboard and back a bit, the chances of flying forward are far less. 

The crash yesterday was the one I have been fearing and that fear has probably held me back. I was keeping my foot in the loop because I believed that it would stop what actually happened. Knowing that, and believing it would have been safer if I had stepped a lot further forward, next time I sail (hopefully the swelling, bruises and stiffness go by next weekend), I will be practicing "walking the gunwale" while foiling and learning how secure I now believe that it should be.

Stay safe!

[maxstaylock 378]

Shame about the compass bracket.

Are you not old enough for a classic now? 

[F18 Sailor 326]

On 11/28/2020 at 8:26 PM, SimonN said:

A cautionary tale......

Yesterday, I had my first capsize for well over a year, and it was one of the biggest I have ever had in an A. Conditions were a bit unusual - 10-15 knots gusting 22 and 40 degree c temperatures, so it was like sailing in a hair dryer. Travelling upwind, one minute we were not foiling and then the boat was leaping out all over the place. I hooked into one puff and the boat was out of control. The others were doing over 22 knots steady and I was going noticeably faster. The bow was rising and the boat was also coming over on top of me. I still cannot work out exactly what happened but very, very suddenly I was heading forward and I hit the boat somewhere between the main beam and the forestay, landing on my forearm/elbow. I slid over the top of the deck and ended up in front of the main beam. During all of this, my helmet got ripped off (despite the strap being properly tightened), I lost my sunnies, and hat. The compass bracket was ripped off the main beam. Strangely, the compass itself came off the bracket and floated, so I could grab that but the bracket was gone.

I was in a world of hurt, particularly my arm which I couldn't really use. One of my team mates picked me up and I dropped him next to my boat, and he got it up and I limped home. Another team mate found my helmet, so in the end, I was down a  compass bracket and a pair of prescription sunnies. Remarkably, there are no dents in the boat.

A few lessons stand out. I am pretty sure that without a helmet, we would have had a pretty serious situation. Besides a bruised arm, I have some whiplash in my neck today. If I hadn't been sailing with a group, I am not sure what would have happened. I don't sail on my own, because I know people who have swum home after the boat has drifted away, but this has reinforced this. Maybe without friends, I wouldn't have been pushing so hard. So please wear a helmet, make sure it is properly done up and if you do sail alone, have a strategy planned for what happens if you cannot self rescue.

The other lessons are about how you sail the boat. First thing to note is that upwind is way more wild than downwind, even though downwind you are probably going 6 knots faster. On a well set up A, 26-7 knots downwind really is armchair sailing, once you have some experience. I wonder whether upwind will ever feel like that (I doubt it). Maybe what I should have done is to not foil in the big gusts, but the top guys are doing that and as that is who I am training with, I don't want to be left behind.

For me, the most interesting learning has been about foot loops and where to stand. Up until now, I have always foiled upwind with my rear foot in the front loop and a wide stance, because I felt I needed the foot in the loop for security. That didn't help me at all yesterday! What my tuning mates do is to walk the gunwale far more, so in the big gusts, they are trapezing level with the shrouds. With the mainsheet on hard, I now realise that this position is more locked in than being further back with a foot in a loop. Think about it - if the mainsheet is pulling you inboard and back a bit, the chances of flying forward are far less. 

The crash yesterday was the one I have been fearing and that fear has probably held me back. I was keeping my foot in the loop because I believed that it would stop what actually happened. Knowing that, and believing it would have been safer if I had stepped a lot further forward, next time I sail (hopefully the swelling, bruises and stiffness go by next weekend), I will be practicing "walking the gunwale" while foiling and learning how secure I now believe that it should be.

Stay safe!

Good story and lesson for us Simon! I have spent more time foiling upwind in 2020 than it seems I have been going downwind. Gusts are hard to handle in either situation, I would say a tossup as boat handling is easier downwind but upwind at least you have some time to see the gusts coming. I too have been staying in a forward footstrap upwind (this is in a similar location to Mischa, it is a 3rd footstrap and not used downwind), generally I feel this is a good location. Going forward from here gets nervous; I did it once in some quite windy conditions to attempt to get the boat back in the water, standing forward of the shroud and she still wouldn't stop flying and if I got it by a wave there it would be quite bad. That experience had me change up my rigging setup, I moved the weather rudder override to the outboard position (one position in from the traveler), this being the primary power control when upwind foiling. I do think it is better, but I also haven't been out in those conditions again, and I probably won't in 2020 as our season is basically over.

I will also say that one of the downsides of the foiling A is the need to always sail with someone else, or preferably a coach in a RIB that can save you if something goes wrong.

[Butenbremer 10]

On 11/10/2020 at 9:42 AM, flyinggorilla said:

Here is another "learning from the pros" series video. Mischa Heemskerk tacking in hi-res and super-slow-motion at the Dutch 4 Nations Cup 2020. Of course, Mischa won!

Thanks to the people who created the great source video allowing to create this slow-mo.

source: https://youtu.be/1NNyPFDdcVo

Digging this out again: Is it just me seeing Mischa wearing a headset?

[SimonN 718]

9 hours ago, Butenbremer said:

Digging this out again: Is it just me seeing Mischa wearing a headset?

Looks like the same one that our training group uses. Plugs into a mobile phone and we do a conference call to each other. We have used this with 4 on the water. We use the BB Talkin sports headset. Phone goes in lifejacket pocket

[Butenbremer 10]

On 12/2/2020 at 4:39 AM, SimonN said:

Looks like the same one that our training group uses. Plugs into a mobile phone and we do a conference call to each other. We have used this with 4 on the water. We use the BB Talkin sports headset. Phone goes in lifejacket pocket

Hey thanks for the hint Simon! Are you using some dedicated IPxy certified phones or just smartphones in a waterproof bag?

[SimonN 718]

Just a smartphone in a waterproof bag.

[WetSnail 17]

Question from someone who has never foiled: I noticed that in Moths, the distance between the main foil and the elevator on the rudder is a large proportion of boat length, and the rig is fairly far forward, the opposite to A-cats on both counts.  Now, in displacement mode, placing the rig farther back reduces nosediving in a cat, but is that still necessary once you foil?  Is there something to be gained from separating main foil and rudder by the largest distance that the platform allows to give the foils better control over pitch by increasing the lever arm, and place the rig accordingly? 

I don't see any boats designed that way, and lots of smart and experienced people have worked on this.  So what is wrong with this idea, and why are A-cats and Moths so different?

[WetnWild 62]

1 hour ago, WetSnail said:

Question from someone who has never foiled: I noticed that in Moths, the distance between the main foil and the elevator on the rudder is a large proportion of boat length, and the rig is fairly far forward, the opposite to A-cats on both counts.  Now, in displacement mode, placing the rig farther back reduces nosediving in a cat, but is that still necessary once you foil?  Is there something to be gained from separating main foil and rudder by the largest distance that the platform allows to give the foils better control over pitch by increasing the lever arm, and place the rig accordingly? 

I don't see any boats designed that way, and lots of smart and experienced people have worked on this.  So what is wrong with this idea, and why are A-cats and Moths so different?

What you’re suggesting is all soundly based and has been done over the evolution of foiling A’s and remaining within the box rule and general engineering issues. Rigs have moved forward slightly but much further introduces twist issues in the platform and sailing balance factors. The dagger boards have moved significantly forward to gain separation from rudders. The rudders have been moved back a little bit within the limits of the box rule by using longer gudgeons. Not to say there isn’t further development available. That’s the essence of the class. 

[WetSnail 17]

On 12/17/2020 at 4:42 AM, WetnWild said:

Rigs have moved forward slightly but much further introduces twist issues in the platform and sailing balance factors. The dagger boards have moved significantly forward to gain separation from rudders. The rudders have been moved back a little bit within the limits of the box rule by using longer gudgeons.

Thanks for the reply.  I can understand issues with twist, assuming beam spacing is limited by needing to sheet to a traveller attached to a beam.  What do you mean by sailing balance?  The relationship between centres of effort and lateral resistance?  I assumed the relationship between mast, front beam and foils would remain the same, no matter where you placed the three, and that would take care of balance.  Have I overlooked something?

If one designed a boat under the assumption that it always foiled above some threshold speed, would there be any drawback to placing front beam and mast as closely as possible to the bow (say 1.5 metres back), the foils a little back from that, a beam holding the traveller where it needs to be, and a beam just forward of the transoms to limit twist?  That third beam would carry some weight penalty, but could better pitch control from greater foil spacing compensate for that?  Along with some aerodynamic benefit from the sail being a complete deck sweeper, because the crew can pass behind the sail, between middle and aft beam, when tacking or gybing?

The Trifoiler looks like it was designed to maximise longitudinal separation between foils and rudder, and it moved the sails to where the foils are.  Current A-cats look like the longitudinal placement of sail and beam is chosen before the foils are put where they need to be relative to the sail.

[SimonN 718]

I think that there are a number of things you are missing. For instance, the vertical parts of the rudders contribute to lateral resistance. As you move the rig and main foils further forward, the position of lateral resistance doesn't move forward by as much as you move those items, as the rudders stay where they are. That loads the rudders differently which can be positive but it can also be a big negative. Then you need to consider the distribution of lift between the main foils and the rudder winglets. The rudder winglets provide some lift, but they also act as stabilisers. The further away you place the main foils from the rudders, the harder the rudder winglets have to work, which increases drag. Forgetting everything else for a moment, if you stick the main foils up near the bow, the rudders need to support far more of the overall down force of the boat. Add the downforce loads from the rig (pulling in the sail pushes the bow down, easing allows the bow to come up), and you begin to see this as a 3d balancing problem.

 What I believe you need to do is to line up the centre of lift of all your foils (fore and aft) in relation to the centre of lateral resistance. Of course, that varies depending on conditions, point of sailing, where you stand in the boat etc., and some of those are controllable variables. What I do know is that those who have tried moving the rig and main foils a reasonable way forward have not been quick and I think we are pretty close to optimum. Interestingly, Moths have had a similar debate and some have tried pushing the rig and foils forward, but as with the A, it isn't fast.

The final thing to consider is that there is also a compromise between speed and safety. I think that moving the rig and foils a long way forward might make the boat less twitchy, but that is at the expense of speed. I think this is why we see the foils on big tris so far forward - it's safe(r).

You should be aware that the latest A's and Moths are designed by some of the top designers, many of who are leading development in the AC. The guys who design the Exploder A use their work on the A to help validate their VPP and they spend a ridiculous amount of time working on this stuff. Couple that with some of the best sailors doing testing and feedback, you might be surprised at what has been thought of an tested, if in some cases only in the computer (we are up to over 50 iterations of main foils, although many have stayed in the computer). Beam and foil positions are a constant source of debate, and changes have been made to optimise them. I can assure you that the position of the main beam (sailplan) , foils and rudders are considered as a whole and positioned to work together as a package.

 

[WetnWild 62]

On 1/15/2021 at 10:44 PM, WetSnail said:

Thanks for the reply.  I can understand issues with twist, assuming beam spacing is limited by needing to sheet to a traveller attached to a beam.  What do you mean by sailing balance?  The relationship between centres of effort and lateral resistance?  I assumed the relationship between mast, front beam and foils would remain the same, no matter where you placed the three, and that would take care of balance.  Have I overlooked something?

If one designed a boat under the assumption that it always foiled above some threshold speed, would there be any drawback to placing front beam and mast as closely as possible to the bow (say 1.5 metres back), the foils a little back from that, a beam holding the traveller where it needs to be, and a beam just forward of the transoms to limit twist?  That third beam would carry some weight penalty, but could better pitch control from greater foil spacing compensate for that?  Along with some aerodynamic benefit from the sail being a complete deck sweeper, because the crew can pass behind the sail, between middle and aft beam, when tacking or gybing?

The Trifoiler looks like it was designed to maximise longitudinal separation between foils and rudder, and it moved the sails to where the foils are.  Current A-cats look like the longitudinal placement of sail and beam is chosen before the foils are put where they need to be relative to the sail.

Sorry for the delay in replying. I’ve been busy doing bigger boat stuff. I agree balance is a key factor. However as you move the balance factors around it does give some unintended consequences such as those outlined by Simon. It’s a very interesting area of development and while it has some great minds addressing the issues there isn’t an unlimited pot of money to really go radical in the fleet. It’s very much incremental. 

[Erwankerauzen 83]

The longitunal position of the centerboards depends on the type of boat:

1-With a monohull, the centerboard and the sail plan are in the same vertical plan.

2-With a multihull which has her centerboards on the amas, then you must have a look at your boat from the top, put the resultant forces of the rig which must meet the opposite force from the centerboard, so the larger the cat or the tri, the more forward will be the centerboard relative to the rig.

In conclusion, I would say that analogies between Moth & Multihull should account for that issue.

Cheers

[SimonN 718]

13 hours ago, Erwankerauzen said:

The longitunal position of the centerboards depends on the type of boat:

1-With a monohull, the centerboard and the sail plan are in the same vertical plan.

2-With a multihull which has her centerboards on the amas, then you must have a look at your boat from the top, put the resultant forces of the rig which must meet the opposite force from the centerboard, so the larger the cat or the tri, the more forward will be the centerboard relative to the rig.

In conclusion, I would say that analogies between Moth & Multihull should account for that issue.

Cheers

But if you look at the position of all the forces when a Moth is sailing, they are very similar to a Cat. Upwind, the Moth is heeled to windward by a considerable amount. Lateral resistance is produced by the (no longer) horizontal foil, which is well to leeward of the CoE of the rig

[Erwankerauzen 83]

You are right Simon, of course, for the Moth, the lateral force comes from the horizontal main foil when heeled. But the longitunal position of this force is more or less aligned with the vertical strut, so it is not a game changer.

If I try to make things a bit clearer : Would you increase the max beam of an A-Cat to become a "18 square", then you will have to move the centerboard closer to the front crossbeam, everything else equal.

Have a nice week

 

[Erwankerauzen 83]

9 hours ago, SimonN said:

which is well to leeward of the CoE of the rig

After some thinking, I wonder if it is the lateral distance which is important,

or being in the same vertical plan (like the Moth) or not (like a cat) ?

[flyinggorilla 40]

Got my new Mischa sail for my A-Cat and perfect weather to try it out as the new 2021 season starts with this May. 

A-Class foiling catamaran - awesome ride - testing new Mischa sail - best personal 26kn speed - YouTube

The sail is called the Hybrid, reduced the shape in the bottom area for upwind foiling and increased the twist in the design for upwind foiling. For my first ride this season i am stunned to peak downwind max speed 26kn and upwind 18kn, and have stable 22ish knows long runs downwind. Broke my personal speed record already first day on the water. TWS 8-16kn. 

And yes, I trapeze relatively high, as I don't trust my rookie sailing skills enough at water temperatures of cold 9 degree. ;-)

fg

[Dex Sawash 721]

@flyinggorilla

What is the rear camera setup from you video?

[flyinggorilla 40]

22 hours ago, Dex Sawash said:

@flyinggorilla

What is the rear camera setup from you video?

Hi Dex,

I have 3D printed a mount for GoPro 7/8/9 to a chasecam setup. This chasecam is dangling on a bungee about 1.5m above water, and tied to the metal loop of the sail top.

ChaseCam universal GoPro mount by flyinggorilla - Thingiverse

In this video I used GoPro Hero 9. I 3D printed also a shock-protector frame (soft TPU material) to ensure the cam doesnt get damaged or scratches when smacking against the shrouds or the  mast. GoPro Hero9 Shock Protector | 3D CAD Model Library | GrabCAD

 

hth,

fg

 

[barney 13]

Wow, such a cool idea! I bet that the gopro's awesome stabilization helps a lot here.

[flyinggorilla 40]

Awesome multicam A-Class Catamaran foiling at up to 23kn speeds in gusty 10-20kn winds

Fantastic A-Class catamaran foiling day to do a training race on the virtual sailspeedmaster track. Due to this course and west-wind direction most foiling is reach and downwind course. First half is mostly downwind, second half of video mostly reach. And yes, I should have released the traveler a bit more on reach course.

[Lost in Translation 61]

amazing footage @flyinggorilla!

[Waiex191 64]

Very cool footage!  We will be printing those gopro mounts to put on our H16.  As new catamaran sailors we get a lot of pitchpole video and could always use a new perspective.  Thanks for sharing them on thingiverse.

[martin 'hoff 1,002]

18 hours ago, flyinggorilla said:

Awesome multicam A-Class Catamaran foiling at up to 23kn speeds in gusty 10-20kn winds

Fantastic A-Class catamaran foiling day to do a training race on the virtual sailspeedmaster track. Due to this course and west-wind direction most foiling is reach and downwind course. First half is mostly downwind, second half of video mostly reach. And yes, I should have released the traveler a bit more on reach course.

That is a lot of fun! Great video @flyinggorilla

[Agilefalcon 0]

That is excellent video - Love the drogue parachute idea for "flying" the camera. 

 

[Waynemarlow 211]

Anybody got any idea of what the latest A Class and Nacra's are using as the bearing surface / hull entry on the bottom of the hulls, to take the loading of the C Boards. I've seen some photos somewhat back a bit of an actual bearing that rotates to allow the Z foils to go through, but I'm only interested in C Boards.

The other boat maybe the AHPC Viper which has both straight and C Boards ?

Thanks.

[flyinggorilla 40]

2 hours ago, Waynemarlow said:

Anybody got any idea of what the latest A Class and Nacra's are using as the bearing surface / hull entry on the bottom of the hulls, to take the loading of the C Boards. I've seen some photos somewhat back a bit of an actual bearing that rotates to allow the Z foils to go through, but I'm only interested in C Boards.

The other boat maybe the AHPC Viper which has both straight and C Boards ?

Thanks.

My A-Cat only takes Z-foils and has that mentioned rotating opening, so sorry, wont be able to help with C foils.

[Lost in Translation 61]

Except for the DNAs, everything I've seen is a fixed hard bearing surface such as G10 or a reinforced cut out from the hull for the board.  The DNA foiler is the most sophisticated with the rotating bearing.

You'll notice the foilers have a relief area in the hull to minimize drag when the boards are set so outboard in the hulls to maximize lift.  The C board boats generally do not need this as their horizontal span is more limited by the classic definition.

[martin 'hoff 1,002]

23 hours ago, Waynemarlow said:

Anybody got any idea of what the latest A Class and Nacra's are using as the bearing surface / hull entry on the bottom of the hulls, to take the loading of the C Boards. I've seen some photos somewhat back a bit of an actual bearing that rotates to allow the Z foils to go through, but I'm only interested in C Boards.

The other boat maybe the AHPC Viper which has both straight and C Boards ?

Thanks.

Nacra have a sturdy plastic profile. IIRC it's symmetrical so you can imagine it's fairly thin at the foil exit point. It's sturdy plastic, but not G10. 

As I'm used to the loading on lifting foils, the loading on C boards doesn't seem all that demanding :-)

[Justaquickone 67]

3 hours ago, martin 'hoff said:

Nacra have a sturdy plastic profile. IIRC it's symmetrical so you can imagine it's fairly thin at the foil exit point. It's sturdy plastic, but not G10. 

As I'm used to the loading on lifting foils, the loading on C boards doesn't seem all that demanding :-)

Earlier this week I got shown pictures of an older C board N17 .

The outward loading at the top of the case had broken the hull to deck join , centre case and peeled over a metre in lenght of the outer hull right down to the keel line .

[Phat Buoy 4]

My A-Cat Classic (Exploder A13) is just the same as a straight boarder, but with a curved trunk.  Only difference is the ability to move the board backwards and forwards a bit at the top with a slider - no adjustment on the fly, just set and lock in place.  Let me know if want pics.

[martin 'hoff 1,002]

9 minutes ago, Justaquickone said:

Earlier this week I got shown pictures of an older C board N17 .

The outward loading at the top of the case had broken the hull to deck join , centre case and peeled over a metre in lenght of the outer hull right down to the keel line .

It sounds like someone ran into something at full speed. But your description of parts and damage is a bit confusing, do you have a picture you can share?

[Justaquickone 67]

4 hours ago, martin 'hoff said:

It sounds like someone ran into something at full speed. But your description of parts and damage is a bit confusing, do you have a picture you can share?

Sorry , I meant glue join down the middle of the deck .

Wish I had photos as the damage is quite extensive ( write off in my opinion ) , they were shown to me by a customer seeking a quote or advise on repairs .

Apparently no impact but happened when the boat started to lift on the C's.

I suppose the down side of the full EVA deck is that you have no signs of the join failing .

The damage split several of the bulkheads as well with one of the forward ones having a nice hole punched through it from a wayward lump of lead flying forward from the resulting crash landing .

Didn't know they were ballasted up ?

[martin 'hoff 1,002]

2 minutes ago, Justaquickone said:

Apparently no impact but happened when the boat started to lift on the C's.

Maybe it is an early era N17, and those might not have the boxy foil trunk that the N15 and modern N17 have. In that case, what you are saying makes a bit more sense. (and you should then disregard my commentary about strong plastic and G10 sections -- those appear in newer boats).

And yet, I have to imagine that the foil case + hull accumulated damage, possibly from groundings, degraded over time (as you say, EVA deck covered it up) and failed at a later moment under normal-ish forces.