Ah another one sees the light: the foil position for SUP foiling is relative to your center of flotation, here approximated via the sweet spot for the front foot while paddling for the Go Foils (instead of the handle for the Gong template), but the idea is similar:
www.standupzone.com/forum/index.php/topic,33427.msg376852.html#msg376852

Note also how recent Dave Kalama SUP foiling boards keep the mast more centered (compared to prone surf foil boards), hence keeping a significant tail part behind the mast. He cleverly adds tons of rocker in a kind of "whistle tail" to ease the pumping/rocking motion on takeoff, but does not move the mast back, to stay at the proper distance of the flotation center.

That's wack!



I feel this is still a very tail orientated mounting just using a different way to measure the distance from a non-exact location that could be different every time you measured it.

The below image shows that using the 25" measure from middle of his front foot position to front bolt is actually longer than the tail to rear of the mast measure, i'd guess about 2-3" approx. which would in fact put the foil nearly exactly where everyone else believes it should go. on a 7'4" board I would say between about 19-22" from tail to back of mast depending on conditions and size of rider. The reason this works is yes it compliments his paddling position. Most boards that actually work and have somewhat of a general shape will work with the tail measure. This is a line drawn then copied and moved to the tail -


The heavy swallow would give the impression of it being further forward and I should of had the line split the different, but for arguments sake I used absolute tail.

Keep it simple, use the tail. I'll get the Kalmam measures as now I am interested as to actually where his placement is.

Ride safe, keep it simple.

JB

Select to expand quote

JB said..
Keep it simple, use the tail.

"25 inches from the front foot sweet spot on everything" seems to me considerably simpler than things involving tables of measurements and variations depending on the shape of the tail like at: "Surf Mounting Location Guide"
foilmount.com/blogs/installation/foilmount-hydrofoil-placement-guide
or the ranges at gofoil.com/faq/
...

+1 I'm with JB and hate to burst your bubble Colas and you should have got a tape measure out before boasting about Beasho's post on the Stand up Zone on 25" is the magic measurement from centre of front foot to front bolt on the Tuttle , which it is on my Kalama 7-1 BUT that puts the back of my mast 17" from the tail. I also contacted Dave Kalama asked how he sets them and he simply said I measure from the tail. You previously mentioned that this board was set up wrong by Dave Kalama.

You also seem to forget I did set my mast forward on my Blue D-C 7-6 to test your theory and rode it like that for 6 months. I have just cut the boxes out to move them back to 21". It really did wack it's tail on pumping plus on steep take off's it was incredible hard to keep the foil in without standing way forward which is the last place you want to be on step take off's , but yes my feet didn't shift much on smaller waves but the one pro was far out weighed by the cons. Hence that's why I cut it out.

Select to expand quote

Piros said..
You previously mentioned that this board was set up wrong by Dave Kalama.

?

Anyways, you are missing the point. I was stressing the fact that measuring from the handle or foot position yield a simple universal rule, whereas you have to resort to complex fuzzy tables to measure from the tail, which is telling something.
PS: do not watch the latest safety video by Robert, you will have a fit... they use straps, and Sam Pa'e even has fins!

Yes I did watch the video and I have a lot of respect for Robert & Sam for their constant R&D and sharing it all with us with an impartial view.

Is this the table of measurements you are referring to as complicated ?

Select to expand quote

Piros said..
Is this the table of measurements you are referring to as complicated ?

Yes, plus the figure underneath applying corrrections depending on the tail shape.

I for one value the robust exchanges between Colas and Piros.There is nothing worse than R&D occupying an echo chamber where the occupants
feel compelled to agree with one another.Congrats to both gentleman for their enthusiasm and passion!

Select to expand quote

JB said..
That's wack!
. . . on a 7'4" board I would say between about 19-22" from tail to back of mast depending on conditions and size of rider. . . .

JB

I just measured and JB's estimate was correct: It is 20" from the closest END OF THE FEMALE TUTTLE BOX to the End of the Swallow tails.

And, I can confirm that the Tail Does Hit while pumping. While this is NOT ideal the board was still made as a Hybrid SUP / Foil board. I purchased this in a panic to get back on the water quickly when I broke my original Tuttle based foil board.

I was travelling and found an old Aeronautical engineering book "The Fundamentals of Flight."

This passage explains what is going on with regards to the balance point between the Center of Gravity (c.g.) and the Aerodynamic Center (a.c.) of lift. (This is a INDEPENDENT FROM COLAS OBSERVATION ABOUT THE CENTER OF FLOAT)

"The Airplane center of gravity must be close to the aerodynamic center or excessive moments will be created. The c.g. is usually within 10% of c (Chord Length) of the a.c."

Typically the Center of Lift is ~ 25% of the Chord Length, or wing distance from leading to the trailing edge. The GoFoil Iwa wing is ~ 10 inches. This would mean that the the Center of Lift is 2.5 " from the leading edge. What this also implies is that the center of gravity, your center of mass should be within 1 INCH to maintain Stable Flight "or excessive moments will be created" aka you will get thrown off the back of the foil, or be riding NOSE DOWN.

This is theoretical but starts to explain the Empirical sensitivity of the Foils to Front, and Rear foot placement. More importantly how specific the sweet spot is for stable flight.

When I measure everything lines up nearly perfectly.

I am riding with a 30" stance. The center point is very near, but slightly forward of the Aerodynamic Center of Lift. This is required for all aircraft to fly in a stable configuration. The moment caused by the center of mass being forward of the center of lift is countered with a downforce on the Tailwing. If you look at the GoFoil tail it has a reverse camber e.g. the Tailwing foil is flat on the TOP surface and curved on the bottom.

This may also suggest that there is a LIMIT to how short the "Dinner Tray" Foil-boards can go. It is probably no coincidence that the tiny Dinner Tray boards are ranging from 3' 6" to 4'.

My next observation is that this configuration is set up with the large Blue Tailwing designed for the IWA and Maliko 200. I haven't been able to get my smaller KAI Tailwing on this setup BUT maybe the smaller wing will allow for riding the IWA in larger waves.

Hypothetically the smaller Tailwing should impose LESS down force at speed reducing the Bucking Bronco effect felt when the IWA takes off in larger surf. Mmmmmmm?

Maybe Piros, the Hawaiians, COLAS or someone else has experimented with this potential combination.

Hypothetically the smaller Tailwing should impose LESS down force at speed reducing the Bucking Bronco effect felt when the IWA takes off in larger surf. Mmmmmmm?

Maybe Piros, the Hawaiians, COLAS or someone else has experimented with this potential combination

I know Dave Kalama in the early stages was using the old Maliko with the Kai rear wing with some success and this is where the IWA came from. We tried it here without much success as the rear wing was a bad fit. Also tried the Kai on the back of the new 200 just felt weird . The 200 is a slow wing with mega lift and I know the rear wing is there to create down force for stability but I argue that with GF rear wing tips facing down also creates drive and definetly creates more pump. So what I am saying is that by fitting a smaller rear wing it won't necessarily let you go faster but make you more prone to over foil. IMHO

Through tons of testing , towing and foiling on bigger waves , those big fat lipped GF's definetly have a lower terminal velocity compared to the super refined thin Lift Foils , I think this is far more relevant than shrinking the rear wing. Again IMHO....

Select to expand quote

Beasho said..
Hypothetically the smaller Tailwing should impose LESS down force at speed reducing the Bucking Bronco effect felt when the IWA takes off in larger surf. Mmmmmmm?

I have not tried it yet (I bought a smaller tailwing - there are 4 sizes - but did not use it yet), but the good foil riders of the Gong team (Xavier Leroy, Beryl Bisseau, Antoine Civel, and Patrice Guenole of coure) use the smaller tail wing to get more looseness: easier pumping and turning, but they say they lose stability. They also tend to use the smaller tail wing more in surfoiling than on SUP foiling.

But they never spoke of having an effect on the "Bucking Bronco", they advise to tweak the rear wing angle for this (by very small increments: half a degree).

But personnaly I did not experience this: the Gong foil seems to become more and more stable at speed (Hossegor waves can pack a punch), if your feet are well positioned (forward enough), the foil designer told me this is the intended benefit of a flat wing with a narrower wingspan, like the wings of aerobatic planes. I guess the neutral handling of flat wings also make mix and matching wings easier.

My 49th foil session: (I now foil less than once a month).
My 3rd session on the new 400 euros Gong foil, really great (and ships worldwide, wink, wink :-) ), and the 13th on this 6'10" board.

Select to expand quote

colas said..
My 49th foil session: (I now foil less than once a month).

Great progression report.

Question: Why are you only foiling 1X per month? I have found foiling to be FASTER, TURNIER and provides LONGER rides in the mushy surf you are showing. Who wouldn't want that?????

All said:

This should serve as inspiration to anyone who is on the fence thinking that only Kai Lenny and Austin Kalama can ride foils.

Select to expand quote

Beasho said..
Question: Why are you only foiling 1X per month? I have found foiling to be FASTER, TURNIER and provides LONGER rides in the mushy surf you are showing. Who wouldn't want that?????

Because we have these conditions only once a month :-) It is either more surfable of unsurfable with too much wind and huge rips.

In truth, I have a ton more fun with a Short SUP in crappy waves, for instance in the videos below: I have more acceleration, can turn harder, can go in more critical sections of the waves, and the rides are shorter so I do not have to paddle a long trip to back to the lineup. Plus our spots can change dramatically with the tides, I can enjoy hollow waves if they happen. I remember the frustration of going out with the foil in mushy waves and seeing them becoming hollow little peelers with the tide.

I guess I would have been foiling a lot more if I was not in a place with good waves.

Actually, I had to force myself to take the foil this morning. I enjoy the foil for the technical challenge, and out of curiosity, but frankly, SUPing with a proper board is pure simple fun for me. Or I would chose to work instead of going in mushy conditions.

Plus I can run 1 mile to get to secluded breaks without crowds with a 6kg SUP... etc, etc...

Select to expand quote

colas said..
My 49th foil session: (I now foil less than once a month).
My 3rd session on the new 400 euros Gong foil, really great (and ships worldwide, wink, wink :-) ), and the 13th on this 6'10" board.

Is Gong shipping all their products worldwide now, or just the foils?

Select to expand quote

exiled said..
Is Gong shipping all their products worldwide now, or just the foils?

They ship their products worldwide easily when it can be done simply by the post office (i.e. a square parcel with the sum of length + height + width being less than 2 meters), and the gear is sturdy enough to resist most transport hurdles (e.g: the foil in its foam case, inflatables, fins, kite sails, 2 part paddles, ...). The shipping cost of a foil to OZ or the US is around 100 euros. It also means it is simple for the customer to return the product simply by their post office if they are not satisfied.

https://gongsupshop.com/epages/box1707.sf/en_GB/?ViewObjectPath=%2FShops%2Fbox1707%2FCategories%2FLivraisons "In the case where you want to Order your merchandise from another Country or Region, please make contact with our Commercial Team for a personalized estimate for those shipping fees."
For boards, they can ship them but you have to contact them to find a transporter, or provide one. And be aware that it will not be realistic to expect to return the board in case of problems, and support issues will be solved by (partial) refunding rather than returning the boards: i.e. if the board arrives damaged in the transport, depending on the damage, either a new one will be sent or they will refund the repair at a local place. Or if the repairs are not possible (e.g. too extensive repairs) they may send you a new board free and ask you to sell the old one locally and send them the money (if you ask nicely :-) ). If this is an issue for you, it is better to buy local, of course.

Select to expand quote

exiled said..

colas said..
My 49th foil session: (I now foil less than once a month).
My 3rd session on the new 400 euros Gong foil, really great (and ships worldwide, wink, wink :-) ), and the 13th on this 6'10" board.

Is Gong shipping all their products worldwide now, or just the foils?

They will ship foils to Oz but not boards.

Shame shipping is that steep, cause the foil price is great. How much lift do you think the 80cm Gong foil gives? I'm about 106kg and my Kenalu 775 Iwa doesn't really get me enough to lift off on smaller days. I'm hoping to find something with a little more power without going all the way to a downwind sized foil.

Select to expand quote

colas said..
My 49th foil session: (I now foil less than once a month).
My 3rd session on the new 400 euros Gong foil, really great (and ships worldwide, wink, wink :-) ), and the 13th on this 6'10" board.

Colas,You have convinced me to put the footstraps back on..[My first steps]
supwindfoil.blogspot.com

Select to expand quote

makesurf said..
Colas,You have convinced me to put the footstraps back on..[My first steps]
supwindfoil.blogspot.com

Well, you definitely do not seem to need straps... Your flying jybe is impressive, must be quite tricky!

Select to expand quote

exiled said..
Shame shipping is that steep, cause the foil price is great. How much lift do you think the 80cm Gong foil gives? I'm about 106kg and my Kenalu 775 Iwa doesn't really get me enough to lift off on smaller days. I'm hoping to find something with a little more power without going all the way to a downwind sized foil.

I weight now 97kg, and the waves in the video clocked at 6s period at the buoy. So, depending on what you call small, I think it should be OK for you. In my experience the speed of the wave is more critical than its size, so I don't think that a foil this size will be enjoyable enough for you under 6s of period. But as the Gong 80cm has a 1675cm2 (similar in size to a GoFoil IWA) and your foil 1496cm2, it should lift you more than your current foil.

On the video the foil offered plenty of lift, except when the wave entered too shallow waters and was slowed down, which seems to tell me that that I should not be going out with waves of 5s period or less.

This said, I haven't tried other foils, I can only compare by the surface numbers.

The waves were about 1ft 10 second when I was trying to foil. I was able to catch and ride these waves for about 100 ft, but not enough speed for lift off. I'm still a beginner, so maybe a more experienced person could have pumped on the board onto foil.

Exiled

Get a bigger foil. Even if it's downwind based.

Your water time and enjoyment will increase exponentially.

120 kg here. Surfing tiny waves every day in the Florida summer.

GoFoil Maliko 200 here. Pumpimg back out and getting multiple waves.

Turns just fine for what I need.

Dont waste time on a smaller foil if you dont absolutely have to.

No awards given for the smallest wing or the most pumps.

Bigger wings maximize the fun for big guys like us.

That might have sounded too strong.

But I started on a little GoFoil Kai, the a Pelican, then... and then... and then.

I wish someone had told me from the beginning to go straight toward a "downwind" foil.

There is no trick around it. You need large wings and a thick leading edge if you are a big guy and you want to get up and fly and stay flying on traditional foils.

It would have saved me a lot of time and money if I knew that early on.

No worries, it was well taken. I'm for sure picking up Ke Nalu's larger wing when it comes out, but they have been slow to market. I was just thinking that the Gong foil with its low price point could be a good stop gap and back-up foil. It feels like I'm just a little short of power on my current wing, so the hope was that a wing with an extra 10% of surface area might be enough to make the difference.

For another value option...

Robert / Blue Planet has a big Easy Foiler foil... He says its roughly between the Maliko 200 and the Iwa.

They seem well priced at $1,249 and full carbon.

I havent tried it yet. But Robert's Easy Foiler boards work great... And easy, as advertised. I bet his foil is too.

I just got a 2019 Naish XL today. It arrived... With no plate bolts. I have tons of plate bolts. But Naish uses smaller plate bolts than everyone. Argh.

So no flying it today... Or a few days. Until the bolts get here.

Anyway... Cant stop spending money on these darn things.

So far Maliko 200 gets the most use.

Yeah, if the Ke Nalu 970 ends up being too big I'll probably go over to the Blue Planet set up. It is good to see some in-between sizes showing up in different ranges, gives me hope I can get something dialed in eventually.