Mast position for pumping

[SUPdad]

I’m still (for ages now ) trying to learn to pump back out.  Currently on a 4’10” board and Axis foil. 910 and 1010 wing, ultra short fuselage, and 460 tail. I find the Axis fairly tolerant of mast position, mostly meaning when you take off, the initial lift doesn’t feel overwhelming and I can keep the foil in the water while standing up. Most of the time, my back foot seems to be just in front of the mast...this is comfortable for me and doesn’t require a lot of front foot pressure.

I’m wondering if the feel I’ve grown to be accustomed to is making it harder to pump. There is a thread here on the forum that talks about sucking your feet up so the board rises with your feet...something like that. While I feel that happening, it makes me wonder when I see others pumping with their foot over or behind the mast. This would cause the board to rise higher/quicker, I would think?

Anyone have thoughts about all this?

[Hdip]

Watch that on repeat. Listen to all the progression project early episodes. Move your mast forward a 1/4 inch forward. Or back. Whatever feels best.

Here’s a nice long write up.

https://foil.zone/t/pumping-front-foot-back-foot/10872

[Califoilia]

I'm finding that it's as much about technique as it is foil/mast setup...within reason regarding wing choose obviously (your 910/420/US on a 4'10 board should be fine).

That "sucking your feet up" - along with the timing of the paddle stroke(s) - is/was that hardest thing to learn. I even tried just holding the paddle, and using my arms "proner style" to help my timing/unweighting of the board...but my lame brain just can't let me get away from the paddle I've used it for so long now. 

I'm also finding that the shorter the board, the easier it is, and have finally been able to start connecting waves with my new shorter sup...with the same wings/setups that I wasn't able to do in the past with even just a 6" longer board. That was for the sup foilers out there, as I'm assuming you're on a 4'10 prone board SUPdad, and that should be short enough.

So really, I think it's more about timing technique, more so than a few fractions of on inch either way of mast placement. Just as an FYI, I never change my mast location, regardless of wing combo or fuse length I'm running for the day.

[Califoilia]

Watch that on repeat. Listen to all the progression project early episodes. Move your mast forward a 1/4 inch forward. Or back. Whatever feels best.

Nice choose of clip Hdip...and from it, I can attest to the one thing that's helping me the most...and that's that once you get the board up and over...let the wing work, and glide a bit.

I was in such a hurry, madly pumping for all I was worth, I was pumping/pushing the nose down to quickly, and not letting the wing do its thing to glide a bit, and only pump it when you just start to feel it fade down a bit.

You might try that SUPdad, it might be what you're doing as well, and could be the missing link(up).

EDIT: Jason Miller is one of, if not the best foiler at my spot is who I've learned the most from, and demoing the technique I'm trying to explain...

[PonoBill]

Cool video Cali--I can't see how any shortboarder could watch that and NOT say "I gotta get a foil".

I don't have any problem understanding how foil position on a board affects takeoff, but unless the foil is so far back that you can't put your foot over or behind it, or you're using straps, or the bottom rocker is so great that it's holding the nose up in the air, I can't see how the position relative to the board would affect anything. Once the board is in the air, your position is what matters. You weigh at least ten times as much as your board. I'm closer to 20X.

I do think that if you're standing with your back foot forward of the mast to reduce front foot pressure it might be time to look at the incidence angle between your stabilizer and wing. If it's more than three degrees it's going to reduce the amount of glide you get substantially. It's like an airplane with the elevator trimmed up, maintaining its flat AOA by shifting all the weight forward. You need a little bit of incidence angle for stability, otherwise, it will effectively alternate between up trim and down trim at a zero AOA, but if you have even a tiny bit too much you need a lot of nose weight to compensate. Any RC glider pilot knows about that. Beginning pilots fly with a little incidence and more nose weight. Advanced pilots reduce the incidence angle to near 0 and use less weight. When they start flying fast you'll see the best pilots have the tail wagging up and down because they have so little incidence. They tweak a tiny amount of trim into the elevator (same as the stabilizer) and the wag disappears, but the plane also slows.

We don't have dynamic control of the elevator as most RC glider pilots do, though there is a version of the sport called "rudder only" that also relies on initial setup, as we do. It's easiest for beginning foilers, and for that matter anyone who doesn't care to mess with factory settings, to use a foil set up for easy liftoff and stable flight. But it is limiting, and might not do what you need.

You can use an incidence angle measuring device intended for RC planes or Admin's measuring method, or you can just add a thin washer on the front screw between the stabilizer and the fuselage and see what it does. It will get up slower, and you'll need to get used to that, and it will require less front foot pressure which means you need to move back a bit, but it might make a huge difference in glide.

If you think about what people are doing to pump, they are shifting their weight forward of, and then behind the center of lift of the wing/stabilizer combination. As a thought experiment, picture taking incidence angle to an extreme so you have to stand on the nose with both feet. Pumping would consist of jumping up and down and would be very hard to time. Worse yet, the extreme incidence angle would be hugely draggy and you'd get no glide.

I can't pump for shit, not because of my setup, but because of my knees, but I brought my incidence angle down to 1.5 degrees for winging and 2 degrees for surfing and it made a huge difference in how much I can pump and glide with my feeble efforts. I think the reason I can suddenly tack with some success is that with an 1150 and a 390 tail with the incidence angle at 1.5 degrees I can glide until there's just no forward motion left and the wing just falls straight down. with just moderate speed I can cross the eye of the wind, get the wing transitioned, and accelerate away long before the foil starts to slow significantly and lose lift.

[Califoilia]

I don't have any problem understanding how foil position on a board affects takeoff, but unless the foil is so far back that you can't put your foot over or behind it, or you're using straps, or the bottom rocker is so great that it's holding the nose up in the air, I can't see how the position relative to the board would affect anything. Once the board is in the air, your position is what matters. You weigh at least ten times as much as your board. I'm closer to 20X.

I have accidental anecdotal supporting evidence to your hypothesis here PB...that says you're correct. I'll try to keep it short...

Finally got the new board, and since I don't want any holes in my decks any longer (just potential leak sources), I use two NSI sticks-on strap inserts for the front strap, and done.

In prior boards I'd put a couple guesstimation marks on the deck pad where I thought they'd go, take a strapless session or two to see where my foot was in relation to the dots, and then install the stick-ons accordingly.

With my new board being 6" shorter, 1" narrower, and what I thought was the bare minimum of volume (turned out I have way more than I  need), I didn't want to try that strapless method with this one, because I do use foot side-to-side pressure on front strap to help me balance my boards when paddling or just standing. So this time I went to a StandinDan's pool, found approximately where I had to have me feet to have the board level in a standing position, and then paddling with a few short paddle strokes in the limited area available...marked my front foot position with some blue tape, and went home to install the inserts.

Once I got started and not being 100% confident with just that, I started getting carried away with math calculations from my 5'7 board's strap place relative to its mast placement, and came up with a new placement for the inserts. Ugh, let's just say I should've just gone with the tape marks, and called it good. First time out with the board, I found that I'd placed the strap about 3/4 of an inch to an inch too far forward from where I was comfortable standing, paddling, and flying. I had basically just my toes under the strap doing about next to nothing the whole time.

Not wanting to attempt to pull up the ill-placed inserts, and not wanting to add an additional set behind them, I took a shot and just moved the mast forward 3/4 of an inch, and everything balanced out perfectly. My stance was perfect with the now correctly placed strap, and my rear foot free to move around atop the mast how I've always done it to get more or less lift depending on the wave I was on, or what I was trying to accomplish.

Long story short...mast placement isn't as important as the foot placement on the board above it...and I didn't notice any difference in my ability to get up and flying on takeoff. If anything, it was easier to pull less board in front of my front foot than it was a little further back.

[PonoBill]

Yeah, I just shove my mast all the way forward on any board and then figure out where my feet should be. Fully forward puts the fuselage more or less parallel to the board. For some boards, my current flying dutchman for one, I still need to shim the mast base to get the fuselage parallel to the water surface when I'm standing on the board. The only reason this matters to me is that having the fuselage angled down is draggy when I paddle for a wave. I don't know what having the fuselage pointing up would do, I'd have to shim like crazy to find out, most boards have at least a little bit of tail rocker.

It tends to be a little easier to come up if the mast is pushed back, in most cases that means less float behind the mast that you have to work against to angle the foil up. If you don't have a big tail bevel that might be important, but if your fuselage is angled down because of tail rocker than I don't see where the gain might be. Anyway, it's not a problem for me, I have enough weight to toss around so changing the attitude of the board isn't a problem. Falling off the back is a bigger issue.

[jondrums]

I can't see how the position relative to the board would affect anything. Once the board is in the air, your position is what matters. You weigh at least ten times as much as your board. I'm closer to 20X.

I'm sorry to say that this is not at all my experience for pumping.  For riding along, yes you're totally correct.  If you care about pumping, I have found that it is very important for the foil lifting center to be matched or slightly forward of the center of mass of the board and foil.  This can be checked by holding the board upside down and finding the balance point on the wing where the board sits perfectly level.  That point should be just behind about 1/4 of the way back from the leading edge of the foil.

During pumping, if you're doing it right, the board is completely unweighted.  During this moment, the forward speed is translated to altitude (the foil lifts up the board).  This is the same moment we talk about "sucking your legs up under you".  If the center of gravity of the board/foil is too far forward of the lifting center, the board will go nose down and refuse to rise up.  Very difficult to pump.  This makes a huge difference in my experience.  This whole concept is central to the reason many SUPfoil boards are very difficult to pump.

When riding a fairly long SUP, where the weight is too far forward - the only way to pump successfully is to not completely unweight your feet.  You have to keep a small amount of push on the back foot, to counteract the forward center of gravity.  This extra force, combined with the weight of the board/foil limits how much rise you get.  Its possible, but a lot more work.

[PonoBill]

A 13-pound board and a 200-pound guy. unweight half your mass and it's still 10 to 1 you vs. board. Think about it. Pray about it if you like. but seriously, no. The center of gravity is of the system, which is foil, board, and rider. The board is a minor part of that equation unless you're talking about something wildly inappropriate to pump--like maybe 14 foot downwind board. Watch any video of the good guys pumping--do you think they are doing more than slightly unweighting? Do you really think you unweight all your weight? Stand on the kitchen floor, swing your arms and suck up your legs and let me know if you levitate for a second--or even get off the ground for a nanosecond. Sure, the shorter the board, the easier it is to pump, but guys like KDMaui were pumping to the lineup from the beach on big boards long ago.

And if you thought what you say you do then you'd just shove your mast all the way forward as I do, which moves the board mass as far back as it's going to go.

[jondrums]

yes, there is nearly zero weight on the board for a moment while pumping.  If you're doing it correctly. yes nearly zero weight.  It is essentially like jumping on the kitchen floor, and yes your feet would leave the floor.

[Hdip]

I also think mast position is much more important on the short prone boards. You don’t have as much room to move your feet around. And yes us prone guys do move our feet around a lot. So a quarter inch in mast placement makes a difference. When I kick out of a wave to do a long pump out my front foot moves back and my back foot moves forward.

[Dontsink]

A 13-pound board and a 200-pound guy. unweight half your mass and it's still 10 to 1 you vs. board. Think about it. Pray about it if you like. but seriously, no. The center of gravity is of the system, which is foil, board, and rider. The board is a minor part of that equation unless you're talking about something wildly inappropriate to pump--like maybe 14 foot downwind board. Watch any video of the good guys pumping--do you think they are doing more than slightly unweighting? Do you really think you unweight all your weight? Stand on the kitchen floor, swing your arms and suck up your legs and let me know if you levitate for a second--or even get off the ground for a nanosecond. Sure, the shorter the board, the easier it is to pump, but guys like KDMaui were pumping to the lineup from the beach on big boards long ago.

And if you thought what you say you do then you'd just shove your mast all the way forward as I do, which moves the board mass as far back as it's going to go.

Balancing the board and foil as Jondrums says is the method KdMaui uses and proposed on the Prog Project podcast,for prone and Sup.
It makes a lot of sense from an energy saving point of view,swinging mass around needlessly is not efficient.Everytime you pump or load G's in a turn you are going to be fighting the nose inertia.
And i would say it has more effect on bigger boards,on a 5 foot or less prone you do not have much room and take off behaviour has priority for me.

[SUPdad]

Watch that on repeat. Listen to all the progression project early episodes. Move your mast forward a 1/4 inch forward. Or back. Whatever feels best.

Here’s a nice long write up.

https://foil.zone/t/pumping-front-foot-back-foot/10872

Thanks, Hdip!  I can’t see that video on foil.zone...won’t open for me.  Is it posted anywhere else?

[SUPdad]

I'm finding that it's as much about technique as it is foil/mast setup...within reason regarding wing choose obviously (your 910/420/US on a 4'10 board should be fine).

That "sucking your feet up" - along with the timing of the paddle stroke(s) - is/was that hardest thing to learn. I even tried just holding the paddle, and using my arms "proner style" to help my timing/unweighting of the board...but my lame brain just can't let me get away from the paddle I've used it for so long now. 

I'm also finding that the shorter the board, the easier it is, and have finally been able to start connecting waves with my new shorter sup...with the same wings/setups that I wasn't able to do in the past with even just a 6" longer board. That was for the sup foilers out there, as I'm assuming you're on a 4'10 prone board SUPdad, and that should be short enough.

So really, I think it's more about timing technique, more so than a few fractions of on inch either way of mast placement. Just as an FYI, I never change my mast location, regardless of wing combo or fuse length I'm running for the day.

This is a prone board. I actually started on the prone because pumping is so hard on a standup. Well, I guess I don’t really know that but the prone guys figure it out way faster and intuitively we know a smaller board should be easier.

The weird thing is in my quest to figure it out, I’ve experimented with shims when using the 910 wing. At first I thought the negative shim (the one that gives less lift) helped. Then I tried moving the mast forward, thinking that might help more. Struggled more and couldn’t figure out why. Then moved the mast back and it seemed easier. Wtf?!?! Then I tried the positive shim and, for a while, thought that helped but eventually took it off. Then got a smaller board, the one I have now, and that helped a bit. Then got the 1010 wing and that also helped.

But, like you said, it’s all about technique. And that’s something I definitely have not developed yet. In the video you posted, his foot is way behind the mast. Different setup, of course, but pretty drastic difference from where my foot is. And not sure if it’s a style thing, but the way he crouches and bends his back knee, sure looks like 90% of his weight is on his front foot.

Anyway, thanks all for the responses. Hopefully there’s more discussion that will eventually get that light bulb in my head to turn on. 

[PonoBill]

It may well be that position of the board weight is more important than I understand. I'll probably never know directly since I don't expect to be able to pump far. But there are a heck of a lot of factors in play, not the least of which is simply believing you have the right setup. I've experienced the fallacy of human perception of physical systems hundreds of times in racing vehicles. You have to be at the very pointy end of experience and talent to "feel" a change of ten percent. The 99.99 percent rest of humanity gets by with a much broader band. Looking at the video of KDMaui, standing with his back foot about five inches forward of the mast, and pumping about as feebly as I do tells me there's a lot more to this than board position.