Messages

1

The Shape Shack / Re: Maximum Displacement Hull Speed

« on: March 14, 2023, 11:12:33 AM »

I'm not an engineer but does nothing take into account the apparent weight of the supposed displacement/planing  hull and just how much water that hull is actually displacing once the foil begins to apply a considerable amount of lift.  When the foil lifts 90% of the board and rider weight, could not the very features designed for planing then become more advantageous versus the displacement portions of the same hull. Having spent considerable time doing flatwater pop-ups, the hopping/slapping phase, just before lift off, consists only of the very flat bottom of board temporarily touching the water's surface .  If the apparent weight of this board is only a fraction of its actual weight(from foil lift), could not planing occur during each, ever accelerating, touch down? just wondering.

This is a good point i think.
IMHO planing does happen for sure on touchdowns and it is the main reason for the hard chines and planing shape bits on a Kalama or similar design.
Round surfaces create a lot less lift at the same speed so they bog down more.
As always there has to be a compromise between an "ideal" displacement hull like a Surfski or K1 and a planing surfboard .
It might take some time to find out what is best , there are many variations possible and different uses (DW,light wind Wing, SUP surf unbroken waves etc...).

2

The Shape Shack / Re: Maximum Displacement Hull Speed

« on: March 12, 2023, 03:32:19 PM »

This is interesting.
The longer=faster displacement hull is something i have been told since i started sailing as a kid.
This explanation is the best i have read:

https://guillemot-kayaks.com/sea-kayak-recreational-kayak/petrel-play-petrel/are-longer-kayaks-really-faster

I still have to chew trough it but longer=faster is not that simple it seems.

Lots of info and studies on kayak hulls,which are longer than ours but a lot closer than sailing boats in dimensions,weights and speeds.

http://www.oneoceankayaks.com/kayakpro/kayakgrid.htm

3

The Shape Shack / Re: Stiffening up a Carbon Mast

« on: March 10, 2023, 08:24:06 PM »

https://www.facebook.com/groups/232666917793846/?ref=share

4

The Shape Shack / Re: Stiffening up a Carbon Mast

« on: March 10, 2023, 11:28:02 AM »

From a board building group on Fbook i remember guys saying they had done this but with lots of delam problems.
You are only going to get  a mechanical bond as the mast is fully cured epoxy.
The outer layer is going to take the biggest traction (and compression too?)  loads.

5

Foil SUP / Re: Compressed air tank for filling wing during downwinder foil SUP

« on: March 01, 2023, 05:10:29 AM »

Have a look into the Black Diamond JetForce backpacks which inflate avalanche airbags by battery and electric pump.

I have no idea if the battery and pump are already waterproof or can be sealed off to be waterproof. Maybe shrinkwrap plastic around it or something. Or convince Black Diamond to make a waterproof version.

If it could be waterproofed you would have both the inflating system and the backpack to carry your wing in one already made pack. It would just need an extension to the airtube for pumping up and a connector to the wing.

https://youtu.be/4eBMuSfx_UI

That pump is designed for superquick inflation, i am not sure it will go up to the PSI's we need for a wing.

I once test inflated my ABS avy backpack (compressed air) but i cannot remember how hard the bags inflated...i think less than a wing.

6

The Shape Shack / Re: Modularity

« on: February 28, 2023, 06:35:54 AM »

Out of curiosity,how much will they charge for that hub?.
Once you have a "design" polished and ready what would be your guesstimate for a  full front wing (without a home printer,ordering the pieces).

7

The Shape Shack / Re: Modularity

« on: February 18, 2023, 09:55:46 AM »

This project could change foiling in wondrous ways.
When you guys get this tech to work (i think you will) the Infinity or Prandtl or Boxwing that i firmly believe to be the future of foiling might vecome an affordable reality for the masses
Pics are from https://www.facebook.com/profile.php?id=100054654391004

8

The Shape Shack / Re: Copper anodes for galvanic corrosion

« on: February 18, 2023, 02:05:14 AM »

Mmm, you guys are right.
Copper may be useless for protecting alu.
Magnesium and zinc would be it...alu is in fact a good anode for many metals .
I think i will let it go, not going to buy this stuff to protect a gong fuse that is used in lake water only.

9

The Shape Shack / Re: Copper anodes for galvanic corrosion

« on: February 17, 2023, 01:49:17 PM »

It is not so slow Bill.
I have had galvanic damage on a Gong alu fuse that was packed with TefGel and dissasembled&rinsed every couple weeks.
The damage burrows really deep before it can be seen from the outside (pitting,swelling etc).
Galvanic action has been a problem for aluminum  marine applications since day one.
Anodizing and TefGel are great at slowing down the process, but if a little anode will help i am ok with trying.The whole marine industry cannot be wrong on this matter.

10

The Shape Shack / Re: Copper anodes for galvanic corrosion

« on: February 17, 2023, 09:54:59 AM »

https://www.alpinefoil.com/en/search/site/?q=Anode

I remembered wrong , it is Alpine Foil that uses an anode in the mast to alu fuse connection.

11

The Shape Shack / Re: Copper anodes for galvanic corrosion

« on: February 17, 2023, 09:45:56 AM »

https://galvanizeit.org/corrosion/corrosion-protection/sacrificial-anodes#:~:text=Sacrificial%20anodes%20generally%20come%20in,or%20water)%20resistivity%20is%20higher.

if you look at the list of metals, copper is toward the bottom. you would want to use magnesium.  I'm just unsure how conductive carbon epoxy matrix, you might have to sand the epoxy top coat to get the magnesium in contact with the carbon fiber.

I think copper and bronze are the traditionally used metals for sacrificial anodes in alu cruising yachts etc...

Maybe magnesium is better but i have this copper tube and it is easy to use,just drill&hammer into place.

For the steel bolts i could use some 1 or.5mm copper plate and cut washers to fit between the bolts and alu.Copper is soft and it will squeeze to fit i think.
Just trying to delay the alu pitting in a Gong/frankenstein setup.

12

The Shape Shack / Copper anodes for galvanic corrosion

« on: February 17, 2023, 08:47:14 AM »

Will an anode  like the one in the pic (3mm copper tubing hammered into 3mm drill hole) help with galvanic corrosion between Alu and steel and carbon?.
Does the sacrificial anode have to be in contact with the nobler materials (Steel or carbon) or just nearby will work?.
I know there is a brand that is putting anodes in their foils (not sure if it was AFS).

13

Wingsurfing, Windfoiling, Wingfoiling, Wing SUP / Re: Foot placement over mast.

« on: February 13, 2023, 12:36:37 PM »

The front wing is what holds you up.

It is better to set your position using the front wing as a reference point,not the mast.

The center of lift is  about 1/3 of the width  from the leading edge.
A stance that straddles that CofLift is a good starting point as Hdip wrote.



A Takuma foil will place the mast further back than a Naish or Armstrong.But the front wing will be roughly in the same place for all brands.

Even using these estimations is misleading.  The centers all change when sweep, margin, area, volume, etc change.  This calculator is great for watching them move.  https://www.ecalc.ch/wingdesigner.htm.  And theat is just for the front foil. 

Best practice, avoid all of these rules of thumb.  This really blew us up as new riders.

Cannot agree...
First of all this rules of thumb are an initial setup method.
KdMaui balance method to place the mast in the boxes, straddle the CofLift to place straps if you use them.You will be in the balllpark with most brands and foil/board combos.

Fuse,stab,shims,sweep,Armstrong kinkiness... are going to need further adjustment but most foils are pretty similar and will need little tweaking.

IMHO what really screwed beginners (and still does)  is  the fact that foils are not intuitive, understanding the forces they create takes new knowledge for most people,and for the first years most distributors,shop owners,pros etc... could ride the things really well but understod little of why or how to explain it.

So they stencilled those blasted markings on the foil box (more wind-less wind   ) and got busy selling them things.

Rant over,sorry...

14

Wingsurfing, Windfoiling, Wingfoiling, Wing SUP / Re: Foot placement over mast.

« on: February 12, 2023, 11:42:09 PM »

The front wing is what holds you up.

It is better to set your position using the front wing as a reference point,not the mast.

The center of lift is  about 1/3 of the width  from the leading edge.
A stance that straddles that CofLift is a good starting point as Hdip wrote.



A Takuma foil will place the mast further back than a Naish or Armstrong.But the front wing will be roughly in the same place for all brands.

15

The Shape Shack / Re: Ultralight Board Designs

« on: February 12, 2023, 10:07:25 AM »

Congrats Beasho, looks like a sweet ride.
Thx for sharing so many details, will come handy for sure.