Phantasm tail wing winglets

So in my pursuit of the lower boundary of foiling nirvana, trying to maximize my time on the water with the light winds where I live, I wrote a letter to Santa (I've been on the naughty list but pulled a few strings) and he delivered early: a Phantasm 930 foil with an 87 cm wide carbon mast and an 8.0 meter Severne Foil glide 2 sail.

There was no wind yesterday so I spent some time assembling the Phantasm foil, which I'm planning to use on my Starboard FoilX 145 board. More information: I weight just under 75 kg, am 60 years old, reasonably fit, but pumping onto the foil isn't getting easier, hence my quest to make it easy to foil in light air. I live on a river near Savannah, Georgia with afternoon seabreezes typically ranging from 6-12 mph, so the water is always flat and there are no waves or extreme maneuvers planned.

I've been using a Slingshot i99 Hoverglide for the last couple of years. Here's my question: with the Hoverglide, the winglets on the tail wing turn up, whereas on the Phantasm, the winglets on the tail turn down. Can anyone explain to me why this should be the case?

Also, since the FoilX doesn't have a track for the mast, I'm using the jack plate adapter which has a moderate amount of fore and aft adjustability. I'm hoping I have the foil far enough forward to eliminate the "back footed" feeling that I had with the i99 and the deep Tuttle box. I copy a few photos for those who are interested. I'm hoping to get on the water this afternoon if the wind picks up at all.

Do not know why stab tips are downward on one and upward on other. As for light wind foiling, I am 82 kg and fit, use an AFS W95 foil with F1080 cm2 wing for 8-12 knots, under 10 knots use a Aerotech non-cambered FreeSpeed 8.0 sail, over 10 knots and up to ~12 knots use a FreeSpeed 7.2, on a 80 cm wide Goya Bolt 135. The Foil X 145 is only 71 cm wide so that should make it easier to get up in light wind. Stance, pumping technique, and properly setup kit, make a huge difference in light wind, I learned that from Andy Brandt in one of his camps. By the way, see 2 AFS W85 foils for sail on Craigslist in Florida with I think the F1080 wing, but no pics so not 100% sure.

As for being back-footed, if I am back footed it means I am underpowered, because my kit is balanced when powered, so I put on either a bigger sail or bigger wing (easier).

You are on a huge wing in comparison (i99 2391 cm2, PFI 928 2343 cm2), so both have a lot more drag than my F1080 wing, and that will make it harder to get up, and once you are up will go slower and be more susceptible to foil outs with gusts than the F1080. My prediction is the PFI 928 is not going to help you much in your quest for light winds, but will certainly help for foiling gybes! (though similar to i99). I certainly would have bought a bigger wing from AFS if they sold one, when I was trying to get up in light winds, but now I realize why they do not make a bigger wing for light wind windfoiling, it is not needed! You just need good technique and that includes stance and pumping, as well as a properly setup kit, it only takes me a couple of well timed sail pumps to get up in 8-9 knot gusts. Still have time to ask Santa for a lesson with Andy! See some dates on his schedule for January in Titusville and St. Pete.

Here's where I've got mine. But also it's the ptm 926 not that wing so there may be some differences.

Appreciate the comments. Sandy, you are likely right that better technique would help. I actually took one of Andy Brandt's clinics last week and we worked on stance and pumping.

If there's any wind after the World Cup final, I'm going to give it a go.

Yeah looks like you can still push the mast forward without moving the jack plate. Worth adjusting if it's still backfooted to you.

Not trying to rain on your festive parade but that foil looks way to far back for a foil like the PFI928.

if there is anyway Santa could do you a solid with a used wizard or levitator with twin tracks it would open up a whole other world for you. When I tested the i99 on the wizard 130 it was much further forward than your board.

you will enjoy that phantasm mast and solid feel over the hoverglide etc many riders under estimate the importance of the mast in light winds and the 87W is going to be way stiffer than the aluminum mast.

With regards to the wing tips, it must be less drag because it's a much quicker foil and I do not feel as if you give up any stability!, it's a win-win

All lifting surfaces have a flow component that goes from root to tip. This is more pronounced in air than in water, and it is more pronounced at low speeds and high attack angles (such as during takeoffs and landings). The idea of winglets is to reduce the tip vortex from this spanwise flow. Tip vortex creates drag. At low speed and high attack angles, the tip vortex causes the wing to stall more easily. Winglets have been a huge improvement in flight safety.

The airplane industry has studied this for many years. Tips up, tips down, tips both (earlier Airbus), tips big, tips small, on and on. Alaskan bush planes have massive down-turned tips. The advantage of the airplane industry is that they have had wind tunnels to study all this.

OK, back to water. A few people, such as the well funded AC and such, have also made similiar flow devices to study lift and drag in underwater foils. Their body of knowledge is getting bigger and better all the time. We all benefit.

Yes, I think winglets on foils is less important than for air. As mentioned, all sorts of foils out there are performing just fine without winglets.

There is another quite important unrelated benefit of winglets. They do indeed provide the benefit of less tendency to cut your leg when you (inevitably) kick your foil. In July on a fluke fall I kicked the wing of my SAB race foil (no winglets) bad enough to keep me off the water for 4 months. (You can always recognize a foiler (or formula sailor) by all the nicks on their legs.)

I appreciate all of the erudite comments. Just wondering, does Santa's sleigh have winglets too? How do the reindeer avoid too much yaw while pulling the fat guy in the back? And what's the Reynolds number on the sleigh? Maybe there's some carryover knowledge that we can apply to wind foiling.

Stability definitely falls under that nebulous category of "feel".
The overall dihedral profile of the wing and stab are also a major factor.

I quite like a fairly flat wing, downturn tips are too stable in the wider sizes. Anhedral flattening to the tips or even coming up into a little dihedral seems to create a very unsettled and challenging wing, especially coupled with a flat stab.

This discussion, and others like it, are great in that they show the maturity of the sport. In 2016-7, all we wanted was to get up off the water and stay there. Period. A single on-wing reach all the way across the Columbia River was a major accomplishment.

Now we talk about foil dynamics, shapes, aspect ratios, speeds, structures, sizes, the full gamit. Throw in boards and sails, too.

This all happened in regular windsurfing, too, over the years. Kiting and winging, too. You see the improvements every year. It also helps that the riders have all gotten better as well.

It will just keep getting better, and we all will benefit.