Messages

1

Foil SUP / Re: Day 1 downwind training, questions and Barracuda impressions.

« on: May 17, 2023, 06:25:46 AM »

Forgot to mention- having a very large foil will help greatly. That 1210 Kujira may be a bit on the small side for beginner paddle ups. I can only paddle up on the Axis 1150 , 1300 and one homemade foil.

2

Foil SUP / Re: Day 1 downwind training, questions and Barracuda impressions.

« on: May 17, 2023, 05:02:20 AM »

You will eventually become accustomed to the boards balance thresholds.  Just a thought here. --  As far as how many paddle strokes it typically takes, well, maybe you're looking at it in wrong way.  You more likely should be asking yourself, "How many hops and downward pumps does it take to get up onto foil".  As has been shown, certain mutant quality individuals can actually use leg and body pumping alone to get up onto foil.  Very few if, any, individuals, as far as I know, have ever paddled up onto foil with no board pumping(excluding sprint kayaks with foils).  Looking at it this way, we could assume that more speed is generated by the foil, than by the paddle.  Focus your concentration on getting really good hops and aggressive downward pushes to engage the foil, in an ever increasing cadence. Coupling this with some well-timed and powerful paddle strokes will have you up and flying with far fewer paddle strokes.   Typically I am up and flying with approximately 5-8 "paddle strokes/pumps.  You may want to hold off for a few extra pumps for even more speed to build before climbing higher on the mast.

3

Foil SUP / Re: A friend's Naish foil rig

« on: April 03, 2023, 03:44:00 PM »

Thanks all,
He weighs around 155lbs , I think. He started with the “Jet “ foils and is now on the HA 1400.  His initial foil of choice was the 1650 Jet series. His board is a 95L Naish carbon pro Hover .  I rode this 1650 and it felt very pitch sensitive compared to any of my Axis foil rigs. . Not something a beginner needs to deal with. Any advice? I’m seriously considering contacting a machinist to make a stainless steel adapter which would extend the front foil out an inch or more.

4

Foil SUP / A friend's Naish foil rig

« on: April 02, 2023, 02:10:01 PM »

Hello,
I have a buddy who has been learning to wingfoil on a newer Naish rig. Every time I have tried this set up it feels very pitch sensitive and hard to control in comparison to my own foils as well as my Axis foils. This has not made his learning very easy and , as much as I hate to, I advised him to possibly change manufacturer. After trying an Axis advanced fuselage , I gained an insight into what the problem might be. The front foil is too close to the mast on the Naish rig.   I put my buddy on an Axis rig and he actually did better.  Anybody out there have any insight.? Im thinking of having a machinist make an extender piece to bolt on, in between foil and fuselage. Or… does Naish make different fuselages ? Not quite sure what to do.

5

The Shape Shack / Re: Maximum Displacement Hull Speed

« on: March 31, 2023, 04:10:01 AM »

There is a ton of interesting content in this thread for a design newb like me (thank you to the contributors). 

One thing that I'm trying to better understand is how to compare hard chines vs a more rounded hull on a pintail downwind board.  I generally understand the pintail, but more designs have very hard chines in the rear portion of the hull leading into the pintail (Baracuda, FFB Dagger, Sultan, Axis, Etc...).  There are some exceptions with more rounded features (Dale Chapman and Sunova), but they are not the norm.

Wouldn't the harder chines create eddys and drag?  wouldn't softer chines allow for better water release and perhaps less wetted area?



Please help a newb understand the hull design philosophy!  Thanks again.

Just the reverse-  water likes to stay attached to curved surfaces as it flows. Not only is water moving longitudinally along the length of the board but, it is also moving laterally as the board slaps down onto the waters surface as we pump and hop. These hard chines allow this lateral moving water to relaease .  When hulls are curved, the water will ride up along that curved hull trying very hard to stay attached to the hull.  All this added water weight is detrimental to an easy and clean separation of hull from water. I hope this helps.

Thanks for the reply - this is helpful.  If I understand correctly, my assumption that the hard chines were disturbing the flow, wasn't wrong, but it is an oversimplification (assuming linear flow).  My oversimplification didn't take into account the priority of releasing the hull from the water surface. 

So basically if the board weren't on a foil, the rounded chines would be faster, but because the board is on a foil and needs to release from the surface, the hard chines are a beneficial compromise.  But in that case, why do foiling monohull sailboats generally have rounded hull features (AC36)?

Taking this one step further, why do these boards then have soft chines towards the nose?  On a touchdown, isn't release a priority again (in which case harder chines would be beneficial)?

Am I understanding this correctly?

Racing sailboats have almost unlimited power so all that is needed is/are hulls with a high hull speed. No hopping, pumping required. Paddlers have relatively very little power which requires the use of hopping and pumping to engage the foil for additional speed as well as to break free of the water's surface.  The reason the very hard edges generally do not go all the way to the nose is just a compromise to make a hull a bit more forgiving on high-speed touchdowns, as far as I can tell. Some makers bring the hard edges all the way forward and some totally round off the front end. They all work to greater or lesser degrees. Again, compromise is the order of the day.

6

The Shape Shack / Re: Maximum Displacement Hull Speed

« on: March 30, 2023, 09:50:55 AM »

There is a ton of interesting content in this thread for a design newb like me (thank you to the contributors). 

One thing that I'm trying to better understand is how to compare hard chines vs a more rounded hull on a pintail downwind board.  I generally understand the pintail, but more designs have very hard chines in the rear portion of the hull leading into the pintail (Baracuda, FFB Dagger, Sultan, Axis, Etc...).  There are some exceptions with more rounded features (Dale Chapman and Sunova), but they are not the norm.

Wouldn't the harder chines create eddys and drag?  wouldn't softer chines allow for better water release and perhaps less wetted area?

Please help a newb understand the hull design philosophy!  Thanks again.

Just the reverse-  water likes to stay attached to curved surfaces as it flows. Not only is water moving longitudinally along the length of the board but, it is also moving laterally as the board slaps down onto the waters surface as we pump and hop. These hard chines allow this lateral moving water to relaease .  When hulls are curved, the water will ride up along that curved hull trying very hard to stay attached to the hull.  All this added water weight is detrimental to an easy and clean separation of hull from water. I hope this helps.

7

The Shape Shack / Re: Maximum Displacement Hull Speed

« on: March 22, 2023, 08:35:40 AM »

Planing could happen during touchdown, though it's more like a skipping rock than a planing hull, and it's worth remembering that skipped rocks flip over with each touch. It's too dynamic a situation to even guess what's going on, though SurfGTP coupled to a few supercomputers could collect enough data and crunch it to model it.

Ok - I was like "what?" -- I had thought it had to be spun horizontally - and the gyroeffect would not go well with flipping over - but I also checked Google, got lost in the weeds/watched some fun videos including one about converting a clay-pigeon thrower into a "skipper" (of exact same discs, not actual rocks) - there are even some things on not-so-flat rocks and their skipping physics but I can't find anything about flipping?

You'd need to be a lifelong geek and present-day geezer to find the right reference. When I was a kid there was a challenge in Scientific American Magazine to explain the odd pattern that skipping rocks leave in the water. I chucked a few hundred rocks in the Charles River trying to figure it out. Close observation shows that there's a long skip, then a very short one, then a long one...etc., etc. Some guy painted a skipping disc with stripes that showed rotation, and different stripes to differentiate top from bottom, then ran a high-speed camera to record the skips. Turns out that when the stone hits the water it creates a depression that has a definite bow wave pushed up by the stone's forward velocity. The skipped stone "trips" on the bow wave and flips over, taking a short hop, then because of its rotational momentum on the second landing flips higher for the next hop. Lather, rinse, repeat. There was an exhibit showing the experiment in the Boston Museum of Science for quite a few years, which is also where I learned that water molecules in a wave don't move forward, they move mostly up and down in an epicycle.

I can remember a Scientific American article from the late 50s when I was about ten years old, but I have no idea where I put the .6mm extruder hot end that I set down "someplace handy" when I was swapping it in. I've cleaned the entire garage looking for it.

Yes, water molecules in a wave generally move up and down, but if those waves are created by wind, the uppermost water molecules travel slightly forward with each circular motion.  This makes catching a wind blown swell a little easier than catching the wake off a passing lobster boat.

8

The Shape Shack / Re: Maximum Displacement Hull Speed

« on: March 14, 2023, 07:02:50 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.

9

The Shape Shack / Re: Maximum Displacement Hull Speed

« on: March 13, 2023, 02:23:31 PM »

All these boards take advantage of their partial planing hulls, if even only for brief moments. The more powerful the paddler, the longer and more frequent these brief moments of planing become, making displacement hull rules and regulations unworkable.

10

The Shape Shack / Re: Maximum Displacement Hull Speed

« on: March 13, 2023, 12:05:14 PM »

Interesting topic!  It seems to me that there is a hell of a lot more going on here than just dealing with maximum hull speeds. The shape of these boards and the way they are being propelled takes advantage of hull speed, foil induced speed and lift, and planing performance.  Greater hull speed is definitely tops when it comes to getting a board to fly. The additional speed and lift of the foil when pumping gives boards with pronounced bevels (ie. Barracuda rails) produces a narrower width as the board rises. Hence, even greater hull speed. Getting the board to completely leave the water (if only for a split second) , narrows the board a little more and then takes advantage of its planing performance. Hence the very flat bottom and hard release edges for most of its length.  For a flatwater pop up, All this happens in the span of maybe 30-60 ft. So all aspects of board speed become necessary, even planing.

11

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

« on: March 01, 2023, 09:30:25 AM »

Thanks all!  I have a paintball/small SCUBA tank with regulator coming in. Is Carbon Fiber so it should be light enough.  Also have enough adapters from my son's paintball days to rig it up. No need to fill it to 4500 psi. I'm sure I'll get 2-3 fills easily even with filling it to 3500 psi. This could make for some interesting downwinders. 

12

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

« on: February 28, 2023, 10:06:59 AM »

Yes, thank you! Just watched it! That’s what it m looking for. I message James Casey to get some pics, but I’m sure I could piece something together. Just wanted to know what size bottle would work. The video shows it well! Thanks again!

13

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

« on: February 28, 2023, 08:54:44 AM »

Thanks, I'll start searching YouTube.

14

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

« on: February 28, 2023, 04:05:39 AM »

Anybody have any beta on what is needed and how to fill a wing during a Downwinder SUP foil run. Conditions in Maine change often while downwinder foiling. On longer excursions, I thought bringing a lightweight carbon fiber canister of compressed air to fill a wing when those conditions change or my fatigue prevents me from paddling up onto foil. Basically a bailout when the miles get long. I would carry the wing and canister on my back while DW SUP foiling and only inflate my wing if needed. Just a thought, since other iterations of this have already occurred.
Thanks in advance. Paint ball tanks seem to be ideal. I have a high pressure pump(4000 psi) already.

15

Foil SUP / Re: Axis Downwind Boards - inverse relationship of length/volume and width

« on: February 20, 2023, 06:17:47 AM »

narrower boards have less edge leverage when small waves and bumps are encountered.  Wider boards have greater edge leverage, making them roll more.  The stabilizing influence of the mast and foil have a proportionately greater effect with narrower boards versus wider boards.  These narrow boards are far more stable than they would at first appear.  longer water lines also increase stability.