Author Topic: 25” is the Magic Number  (Read 2389 times)

Beasho

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25” is the Magic Number
« on: April 22, 2018, 05:48:53 AM »
New board from Kirk McGinty: 7’ 4” X 31” X 4.5” X 125 liters Bat-Tail hybrid quad L41 with a Tuttle Box.  The beauty weighed in at 16.6 lbs. 

This was the first SUP / board that weighed less than 20.0 lbs that I have ever surfed.  My 2nd foil board.

Summary: The magic distance is 25 inches from the center of the forward Tuttle Bolt to the Sweet Spot for your front foot with the GoFoil Kai, Maliko, IWA and Maliko 200 Foils.

Prior to this acquisition I endured an entire WEEK (without a foil board) and I attempted to SUP again.  The waves ranged from good, to big, with 7 to 14 foot faces in bumpy to super bumpy conditions.
 
BUT IT JUST WASN’T FOILING.

I was dispirited by the lack of STOKE.  A true addict.
« Last Edit: April 22, 2018, 05:57:17 AM by Beasho »

Beasho

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Re: 25” is the Magic Number
« Reply #1 on: April 22, 2018, 05:49:07 AM »
I put out an APB on the StandUpZone and called a few friends. 

Jeff Clark had some 1st generation foil boards with Tuttle boxes.  Used 8’ 3” and an 8’ 6” with strap mounts. 

Then Kirk came through with this hybrid which, despite not having strap holes, was:
  • New
  • Lighter &
  • Shorter than the other options

SOLD!
« Last Edit: April 22, 2018, 05:56:10 AM by Beasho »

Beasho

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1st (Half) Session Report
« Reply #2 on: April 22, 2018, 05:49:19 AM »
1st (Half) Session Report: Disaster! 

The boards reduced swing weight was 100% noticeable.  When carrying the board, and toting it on my bicycle, it was significantly more spritely than my prior L41 which was 8’2” x 4.5” x 32” @ 139 liters and 21 lbs.   

The board was tippy, difficult to stand on and slow to paddle. 

The first wave caught me from behind and I crashed.  2nd wave crashed.  3rd wave almost got up and then I went flying off the Bucking Bronco.  OMG this is a totally different animal.  By the 7th wave attempt and CRASH I was wondering how many sessions this was going to take.
 
I was set back to TOTAL BEGINNER on the foil.  This was after 1,400 waves caught on my prior board in everything ranging from 2 to 15 feet over 100+ sessions.  Short of the Hawaiians and Piro’s crew in Australia few people on the planet have had more experience on a surf-foil.  What was up?
« Last Edit: April 22, 2018, 06:00:40 AM by Beasho »

Beasho

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2nd Half of First Session
« Reply #3 on: April 22, 2018, 05:49:29 AM »
2nd Half of First Session: I will note that the conditions were 6 to 10 feet (Buoys 10 @ 10) with significant chop and a tail-wind.  Non-Trivial learning conditions but in my head PERFECT FOR FOILING.
 
On my 8th wave attempt I had to follow my own advice to beginners “Stay low, put your front foot ALL THE WAY FORWARD and don’t even attempt to fly.” 

I dropped down the face, with my front foot a full 12” in front of where I thought my foot needed to be, and to my surprise the board’s rail stuck to the water.  I slowly crabbed my foot back and the nose gently rose up and I began to fly.
 
The boards sensitivity to foot and weight position felt like a Frisbee vs. the 8’ 2” Cadillac I was used to riding.  After a quick 100 yard flight I crashed off my rediscovered high.
 
I took off on the next wave and flew wonderfully.  I snapped a mental screen shot of where my FRONT FOOT was on the deck and, to my horror, it was 6” well forward of where I thought it should be, but it worked. 

By the end of my FIRST session I had re-learned how to fly based ENTIRELY on my front foot position.  I ended up catching 16 waves with an average ‘successful’ ride length of 172 yards per wave.  My longest ride was 340 yards lasting 50 seconds long.
 
Wow – That was a quick learning curve.   
« Last Edit: April 22, 2018, 06:07:46 AM by Beasho »

Beasho

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Proper Placement of Foot Pads on Board
« Reply #4 on: April 22, 2018, 05:59:53 AM »
I re-learned the importance of foot positioning on a Foil Board.

I pulled out my older, broken L41 and measured the distance from the front bolt of the mast to the center of the stomp pad I had used for my last 1400+ waves.  The distance was 25 Inches. 

I then measured on my new board from the front bolt to the spot I memorized my foot needed to be THE DISTANCE WAS 25 INCHES. 

I ripped of the old stomp pad and placed it centered 25 Inches in front of the forward bolt on my new board.
« Last Edit: April 22, 2018, 06:21:31 AM by Beasho »

Beasho

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2nd Session on L41 Flyer
« Reply #5 on: April 22, 2018, 06:09:41 AM »
I went out for my second session on the board. 

The waves had dropped with 6 to 8 foot faces.

The picture shows my first wave attempt With the installed Stomp Pads.  An immediate success: 350 yards for almost a minute.

In one hour I had 9 successful flights averaging 250 yards. 

I was back in the saddle with a newer, lighter little rocket ship.
« Last Edit: April 22, 2018, 06:23:16 AM by Beasho »

PonoBill

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Re: 25” is the Magic Number
« Reply #6 on: April 22, 2018, 07:37:14 AM »
Great writeup. I've learned the importance of front foot position as you undoubtedly did as a beginner. I moved my footstrap back half an inch and spent a session flying over backward. It's certainly strange that I couldn't compensate by putting more weight on my front foot, and probably a more experienced rider could, but I couldn't.

Enjoy the new ride. I'm looking forward to my new Kalama board. I've resisted the urge to visit it at Dave Peterson's shop for the last two days. I enjoy talking to Dave too much so it's counterproductive.
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FRP

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Re: 25” is the Magic Number
« Reply #7 on: April 22, 2018, 10:03:30 AM »


Prior to this acquisition I endured an entire WEEK (without a foil board) and I attempted to SUP again.  The waves ranged from good, to big, with 7 to 14 foot faces in bumpy to super bumpy conditions.
 
BUT IT JUST WASN’T FOILING.

I was dispirited by the lack of STOKE.  A true addict.


Hi Beasho

This has me worried. I was dreaming about foiling last night. Is it possible to go back to sup surfing once you start flying on a foil?

Bob
« Last Edit: April 22, 2018, 10:08:46 AM by FRP »
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Re: 25” is the Magic Number
« Reply #8 on: April 22, 2018, 11:06:36 AM »
On the few days that conditions were to big for me to comfortably foil, I found that it was easy to transition from foil to sup surfing.  My balance felt like it had improved, although I felt a little rusty with some of my more high performance maneuvers.  By the end of the session things started to click again.  I believe sup surfing to foiling will be a harder transition. 
L41 SIMSUP S4 - 7'4" x 30 1/4" x 4 1/2" 112L
L41 SIMSUP S5 - 7'6" x 27 1/2" x 4 3/16" 106L
L41 SIMSUP S4 - 7'8" x 31"x 4 1/2" 122L - Modded w/ a King's TUT Tuttle box and using a King's foil.
L41 SIMSUP S4 - 7'10" x 30 1/4" x 4 1/2" 120L
Starboard Whopper - 10' x 34" x 4 1/3" 171L - w/ FCS GL-1 fins

PonoBill

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Re: 25” is the Magic Number
« Reply #9 on: April 22, 2018, 01:05:17 PM »
I think it's somewhat like learning a language by immersion. Once you are fluent you can switch back and forth, but until then you create a lot of problems for yourself in both "languages". That's why immersion environments insist on "only French".

For myself, when I was first getting the board to fly, switching off to a SUP to surf caused all kinds of problems. I was pearling on the SUP from weight too far forward and falling because of my foot position and balance. On the foil I was leaning back too much and reverting to surf stance. Eliminating SUP surfing for the interim helped greatly. I still have a way to go to be fluent, but I feel fine on a downwind board, even though I occasionally get frustrated trying to pump it up.
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Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Dwight (DW)

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Re: 1st (Half) Session Report
« Reply #10 on: April 22, 2018, 01:44:21 PM »
Short of the Hawaiians and Piro’s crew in Australia few people on the planet have had more experience on a surf-foil. 
Not really. Everyone I know, myself included, kites their surf foil when the waves are not right, so way more hours flying the surf wing sets.

Beasho

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Re: 25” is the Magic Number
« Reply #11 on: April 30, 2018, 01:55:22 PM »
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.

"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. 

 
« Last Edit: April 30, 2018, 02:09:16 PM by Beasho »

Beasho

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Re: 30” is the Magic Stance Width
« Reply #12 on: April 30, 2018, 01:56:34 PM »
And everything lines up with No surprises.

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.
« Last Edit: April 30, 2018, 02:29:43 PM by Beasho »

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Re: 25” is the Magic Number
« Reply #13 on: July 09, 2018, 01:42:52 PM »
Just want to top this post cause I tried putting a patch of deck pad 25 inches off my front bolt and it worked really well on my Kenalu Iwa 774. I found out I had been putting my front foot too far forward. Being a tall guy, my surf stance is a lot wider and it seems like I have been over stepping my foil. Bringing my foot back made everything feel a lot more stable underfoot. I'm only about 10 sessions in so I'm just starting to get the hang of it, but today was the first day the foil really felt controllable and getting the foot work right helped a lot.

 


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