I had a curious session on the weekend. Conditions were not ideal maybe 10-15 knots onshore.

Gear
7.8m2 race sail
125L slingshot wizard
101 cm ghostwhisper mast tuttle

Foils:
1) sab 940/430 on 900cm fuse
2) sab 800/425 on 1050 fuse

Initally I went out on the sabfoil 940 front wing (1100cm2) and 430 stab with 900 cm fuse, as the wind was light and I figure the greater area of the 940 would be better than the w800(840cm2). w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying but also control the power in the sail. Kind of felt like a game of twister and my lower back was getting very fatigued. Also difficult to point.

After a while I felt like I had done better on similar conditions on my w800 so I switched to the w800/s425 and 1050 cm fuse. Moved the sail mast track forward to the middle. And I did much better. Seemed to point higher, got going easier and didn't feel contorted.

Maybe a physicist can explain why one set up felt terrible and one set up felt doable, I certainly cannot.

This photo shows the relative position of the w800 on 1050 fuse veruss w940 on 900. Based on mast position.


Heres some other photos and a bit of video






?feature=share

The better setup had the front wing much closer to the front foot. In my experience this is always a better setup.

940 is my most used frontwing. I find it well ballanced with 425 stab. Sail is most 4.8 foilfreek. With this setup i have fun in medium and lighter wind. I'm 76kg, you?

I am 76 kg as well

Are you more used to the 800/425 with the race fuse setup? So you need some more time on the 940 probably.
or try with a shim for more lift

much more familiar with freeride set up but a few more sessions on 800. Definitely needs more shim if I use the 940 again

Select to expand quote

thedoor said..
w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying...

Moving the foil back when its backfooted doesnt make sence at all to me. I think if you instead moved it forward 2-3 inches it would have been much better.

Also helps controlling the sail, as gusts generally pull the rider more upright, increasing power on the front foot & therefore causing instability. Having the foil further forward allows more room for error in that regard because the lifting power is also further forward.

There's a huge difference in feel between having to shift balance between "front and back foot" and "more or less front foot" so to speak. Where I (and I dare say most advanced riders) prefer the latter for a multitude of reasons, increased percieved sail control being one of them.

I was all contorted with lower back pain when I started. Basically the uj was too far away from my front foot. Could never get balanced and comfortable in the harness. Add to that, my 135lbs with the high lift of the I76, had me leaning forward to prevent foil out, making it more difficult. In the end, foil mast track all the way back (to prevent foil out), and uj all the way back(good distance between uj and front foot for balance) was a revelation in comfort and control. For reference, I run my front foot strap all the way forward outboard on the rail. Sooo many variables, and everyone is different.
My .02.

Select to expand quote

thedoor said..
I had a curious session on the weekend. Conditions were not ideal maybe 10-15 knots onshore.

Gear
7.8m2 race sail
125L slingshot wizard
101 cm ghostwhisper mast tuttle

Foils:
1) sab 940/430 on 900cm fuse
2) sab 800/425 on 1050 fuse

Initally I went out on the sabfoil 940 front wing (1100cm2) and 430 stab with 900 cm fuse, as the wind was light and I figure the greater area of the 940 would be better than the w800(840cm2). w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying but also control the power in the sail. Kind of felt like a game of twister and my lower back was getting very fatigued. Also difficult to point.

After a while I felt like I had done better on similar conditions on my w800 so I switched to the w800/s425 and 1050 cm fuse. Moved the sail mast track forward to the middle. And I did much better. Seemed to point higher, got going easier and didn't feel contorted.

Maybe a physicist can explain why one set up felt terrible and one set up felt doable, I certainly cannot.

This photo shows the relative position of the w800 on 1050 fuse veruss w940 on 900. Based on mast position.


Heres some other photos and a bit of video

?feature=share

If I well understood the 800 set up you felt good on has the front wingh much forward vs the 940. I would say 5-7 cm from picture. this would have similar effect as moving the entire body back the same amount and massive effect on balance resolving the back foot pressure all the rest being the same.
If you feel backfooted it means that you would need to move your body weight (i.e straps position) more on the back to balance your body/kit combo. Moving the UJ forward has less of an effect but goes in the opposite direction vs moving the foil forward. the effect is less since only sail weight is moved forward so this is not compensating the foil front wing being moved forward even the same distance amount; more or less the ratio on the effect equals the ratio on the weight body/sail which I estimate around 7-8 just to calibrate. this would mean that to make everything equal you should have been moving the mast base forward 7-8 times the amount you moved the front wing forward.
The center of lift of what is in the water need to balanced by the weight distribution of staff above the water (your body and the sail if this is all you are carrying). I would say this is why you felt better with this set up. To prove this right you may try to install rails underneath your board and move the 940 around the same amount forward as you had the 800, or give the 940 the same fuselage of the 800, you would have been slower because of the more drag associated to the bigger foil, but balanced anyway. The above matches what whiteofHeart stated and I agree, you basically moved in the direction he is suggesting. Shimming the stabilizer giving more lift has the same effect of moving the front wing forward though at the expense of some more drag.

You should try the 940 on the longer fuse. When you are talking about moving the mast back, are you talking about the sail mast or foil mast?

Select to expand quote

WhiteofHeart said..

thedoor said..
w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying...

Moving the foil back when its backfooted doesnt make sence at all to me. I think if you instead moved it forward 2-3 inches it would have been much better.

Also helps controlling the sail, as gusts generally pull the rider more upright, increasing power on the front foot & therefore causing instability. Having the foil further forward allows more room for error in that regard because the lifting power is also further forward.

There's a huge difference in feel between having to shift balance between "front and back foot" and "more or less front foot" so to speak. Where I (and I dare say most advanced riders) prefer the latter for a multitude of reasons, increased percieved sail control being one of them.

The foil was in a tuttle box, I slide the mast track of the sail back when using the 940

Select to expand quote

thedoor said..

WhiteofHeart said..

thedoor said..
w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying...

Moving the foil back when its backfooted doesnt make sence at all to me. I think if you instead moved it forward 2-3 inches it would have been much better.

Also helps controlling the sail, as gusts generally pull the rider more upright, increasing power on the front foot & therefore causing instability. Having the foil further forward allows more room for error in that regard because the lifting power is also further forward.

There's a huge difference in feel between having to shift balance between "front and back foot" and "more or less front foot" so to speak. Where I (and I dare say most advanced riders) prefer the latter for a multitude of reasons, increased percieved sail control being one of them.

The foil was in a tuttle box, I slide the mast track of the sail back when using the 940

I would say the main difference is 800/425 on 1050 is the longer fuse. Not only is it moving the Wing further forward, but also it looks like it move the stab back - giving the stab more leverage & creating more pitch stability. IMO you will not get the same stability out of the short fuse. You may be able to balance the 940/430 on 900cm fuse, but with the DT mount you cannot move the Wing forward to compensate so the only real way to achieve balance on the shorter fuse is to move your stance back relative to the foil mast, then you will also have to move the mast base back to remain in a similar stance.

Select to expand quote

gorgesailor said..

thedoor said..

WhiteofHeart said..

thedoor said..
w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying...

Moving the foil back when its backfooted doesnt make sence at all to me. I think if you instead moved it forward 2-3 inches it would have been much better.

Also helps controlling the sail, as gusts generally pull the rider more upright, increasing power on the front foot & therefore causing instability. Having the foil further forward allows more room for error in that regard because the lifting power is also further forward.

There's a huge difference in feel between having to shift balance between "front and back foot" and "more or less front foot" so to speak. Where I (and I dare say most advanced riders) prefer the latter for a multitude of reasons, increased percieved sail control being one of them.

The foil was in a tuttle box, I slide the mast track of the sail back when using the 940

I would say the main difference is 800/425 on 1050 is the longer fuse. Not only is it moving the Wing further forward, but also it looks like it move the stab back - giving the stab more leverage & creating more pitch stability. IMO you will not get the same stability out of the short fuse. You may be able to balance the 940/430 on 900cm fuse, but with the DT mount you cannot move the Wing forward to compensate so the only real way to achieve balance on the shorter fuse is to move your stance back relative to the foil mast, then you will also have to move the mast base back to remain in a similar stance.

Good point about the stab being further back. This photo might be a little off re mast insert alignment but you can see how much further out the back the stab is. Effectively magnifying it's leverage?

Select to expand quote

thedoor said..

gorgesailor said..

thedoor said..

WhiteofHeart said..

thedoor said..
w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying...

Moving the foil back when its backfooted doesnt make sence at all to me. I think if you instead moved it forward 2-3 inches it would have been much better.

Also helps controlling the sail, as gusts generally pull the rider more upright, increasing power on the front foot & therefore causing instability. Having the foil further forward allows more room for error in that regard because the lifting power is also further forward.

There's a huge difference in feel between having to shift balance between "front and back foot" and "more or less front foot" so to speak. Where I (and I dare say most advanced riders) prefer the latter for a multitude of reasons, increased percieved sail control being one of them.

The foil was in a tuttle box, I slide the mast track of the sail back when using the 940

I would say the main difference is 800/425 on 1050 is the longer fuse. Not only is it moving the Wing further forward, but also it looks like it move the stab back - giving the stab more leverage & creating more pitch stability. IMO you will not get the same stability out of the short fuse. You may be able to balance the 940/430 on 900cm fuse, but with the DT mount you cannot move the Wing forward to compensate so the only real way to achieve balance on the shorter fuse is to move your stance back relative to the foil mast, then you will also have to move the mast base back to remain in a similar stance.

Good point about the stab being further back. This photo might be a little off re mast insert alignment but you can see how much further out the back the stab is. Effectively magnifying it's leverage?

Kind of like the 95+ vs 105+ starboard fuses. Front wing in similar places but that extra stab distance really gives a ton of stability.

Select to expand quote

aeroegnr said..

thedoor said..

gorgesailor said..

thedoor said..

WhiteofHeart said..

thedoor said..
w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying...

Moving the foil back when its backfooted doesnt make sence at all to me. I think if you instead moved it forward 2-3 inches it would have been much better.

Also helps controlling the sail, as gusts generally pull the rider more upright, increasing power on the front foot & therefore causing instability. Having the foil further forward allows more room for error in that regard because the lifting power is also further forward.

There's a huge difference in feel between having to shift balance between "front and back foot" and "more or less front foot" so to speak. Where I (and I dare say most advanced riders) prefer the latter for a multitude of reasons, increased percieved sail control being one of them.

The foil was in a tuttle box, I slide the mast track of the sail back when using the 940

I would say the main difference is 800/425 on 1050 is the longer fuse. Not only is it moving the Wing further forward, but also it looks like it move the stab back - giving the stab more leverage & creating more pitch stability. IMO you will not get the same stability out of the short fuse. You may be able to balance the 940/430 on 900cm fuse, but with the DT mount you cannot move the Wing forward to compensate so the only real way to achieve balance on the shorter fuse is to move your stance back relative to the foil mast, then you will also have to move the mast base back to remain in a similar stance.

Good point about the stab being further back. This photo might be a little off re mast insert alignment but you can see how much further out the back the stab is. Effectively magnifying it's leverage?

Kind of like the 95+ vs 105+ starboard fuses. Front wing in similar places but that extra stab distance really gives a ton of stability.

Except it seems the longer SAB fuse does move the Wing significantly forward as well.... so definitely would need to adjust either foil mast position(not possible with tuttle) or stance position...

Select to expand quote

WillyWind said..
You should try the 940 on the longer fuse.

The sab 800 is a race frontwing and needs the race fuse. The 940 has other kind of screw holes distance and can not be mount to the race fuse

When I am back footed on my AFS W95 with any wing, F1080, F770, S670, it is usually because I do not have enough wind pressure on the sail. But if the wind increases, when outhaul is set for light wind, then I will feel underpowered too, have to increase outhaul to move pressure point on sail forward where it normally is.

If I was your weight with a 7.8 sail, and on my F1080 cm2 wing I would need 8-9 knots Max!, cause I (82 kg) now use an Aerotech FreeSpeed 8.0 sail with a 490 cm mast in those conditions!

Select to expand quote

thedoor said..

gorgesailor said..

thedoor said..

WhiteofHeart said..

thedoor said..
w940/s430 was very rear footed so I slid my mast track back 2-3 inches while on the water, to the rear of the track. This helped but it was still rear foot heavy. Interestingly I found it quite challenging physicaly to keep the board flying...

Moving the foil back when its backfooted doesnt make sence at all to me. I think if you instead moved it forward 2-3 inches it would have been much better.

Also helps controlling the sail, as gusts generally pull the rider more upright, increasing power on the front foot & therefore causing instability. Having the foil further forward allows more room for error in that regard because the lifting power is also further forward.

There's a huge difference in feel between having to shift balance between "front and back foot" and "more or less front foot" so to speak. Where I (and I dare say most advanced riders) prefer the latter for a multitude of reasons, increased percieved sail control being one of them.

The foil was in a tuttle box, I slide the mast track of the sail back when using the 940

I would say the main difference is 800/425 on 1050 is the longer fuse. Not only is it moving the Wing further forward, but also it looks like it move the stab back - giving the stab more leverage & creating more pitch stability. IMO you will not get the same stability out of the short fuse. You may be able to balance the 940/430 on 900cm fuse, but with the DT mount you cannot move the Wing forward to compensate so the only real way to achieve balance on the shorter fuse is to move your stance back relative to the foil mast, then you will also have to move the mast base back to remain in a similar stance.

Good point about the stab being further back. This photo might be a little off re mast insert alignment but you can see how much further out the back the stab is. Effectively magnifying it's leverage?

yes, this is the reason why racers are using longer fuses, to get more power without increasing drag at expense of manoeuverability.

I think the smaller stabilizer should be on the longer fuselage which magnifies the effectiveness of the stabilizer, as pointed out above. 430 stab. "looks" like it has less surface area than 425.

Hey Gorgesailor, I presume you have found the combination of 940 and 430 on the 900 fuse to work well together? I have the 940 with the 450 stab, and I think it is too slow.

As mentioned above, the SAB race fuse (either the 1010 or 1100) takes ONLY their respective race wings. See the chart on sailworks.com. The stabs at the bottom of the chart seem to be usable with all fuses. I have the older race 1100 fuse, which takes only the one 900 wing on the chart. I have the 425 stab for it. The newer 1010 fuse fits a bunch of wings and stabs.

If you are using a 940 wing, you are limited to the non-race fuses. I have the 950, 940, and 720 wings, and 450 stab, with the 900 fuse. I would like to try the 430 stab in the hopes of getting a bit more speed.

Select to expand quote

segler said..
As mentioned above, the SAB race fuse (either the 1010 or 1100) takes ONLY their respective race wings. See the chart on sailworks.com. The stabs at the bottom of the chart seem to be usable with all fuses. I have the older race 1100 fuse, which takes only the one 900 wing on the chart. I have the 425 stab for it. The newer 1010 fuse fits a bunch of wings and stabs.

If you are using a 940 wing, you are limited to the non-race fuses. I have the 950, 940, and 720 wings, and 450 stab, with the 900 fuse. I would like to try the 430 stab in the hopes of getting a bit more speed.

I think its hard to reach the top speed of your foil without control, and therefore sometimes a faster stabilizer may not translate to higher speeds if it results in poorer control. However, I think you should definitely try the 430, not neccasarily to go faster just to see if you like it. Did you try the 425 on your 900 cm fuse. 450 is still my favorite stab, 425 is between 430 and 450 interms of lift, so in theory 430 should be faster. I presume you are fastest on the 900 wing?

Yes, of course. Good point. I will have to try my 425 stab on my 900 fuse with, say, the 940 or 720 and see how it works.

please, has anybody tested the new SAB foil 103 cm mast? How does it comare in terms of bending and torsional stiffness to the F4/Phantom/Z ?
For 80 kg what's the best 7-15 kts fast freeride kit to fit with (using a 83cm foil board) ?

Select to expand quote

segler said..
Hey Gorgesailor, I presume you have found the combination of 940 and 430 on the 900 fuse to work well together? I have the 940 with the 450 stab, and I think it is too slow.

My response was theoretical - purely speculative based on how the fuselage affected the positions of the front wings & stab relative to the mast... Very important on Tuttle based system since you must adjust your stance relative to the center of lift instead of moving the center of lift as on track mounted boards.