For you windfoilers out there, I'm riding a slingshot wizard v3 130l with a ptm926 phantasm foil with a 5,7 or 6,7 sail for light winds and feel really balance. When I change for smaller sails in higher wind, the board is harder to control and I have more front foot pressure. Do you change the mast position more in front or maybe get the foil more in back of the board in this condition?
Select to expand quoteLechatMB said..
For you windfoilers out there, I'm riding a slingshot wizard v3 130l with a ptm926 phantasm foil with a 5,7 or 6,7 sail for light winds and feel really balance. When I change for smaller sails in higher wind, the board is harder to control and I have more front foot pressure. Do you change the mast position more in front or maybe get the foil more in back of the board in this condition?
I move my UJ further back with larger sails. About 2" difference between my largest 5.3 and smallest 3.7 sail. It may depend on other factors, sail tuning, brand, skill level. To me the bottom line is mast base pressure. My larger sails push down harder in a gust driving the nose down. You can certainly compensate with your riding style. I have forgotten to move the base, and just use more rear foot pressure to compensate until I get to a safe spot where I can drop the rig and adjust. Early in my learning process, I experimented moving the base very far forward. That got me into a porpoise situation up and down when sailing on a Broad reach that was very hard to manage. The closer the UJ is to the wing, the less drastic the base pressure is. I don't freestyle and use outboard foot position. If you look at Balz Mueller and other frer style set ups, the front foot is very close to the UJ. He talks about it in one of his videos related to reducing the base pressure effect for the insane moved he does.
I always adjust mast base position when switching between sail sizes. Bigger sails are heavier, smaller sails are lighter.I wouldmove the mast base forward and keep the foil in a neutral position. If it's not enough and you're still getting too much front foot pressure, push the foil back.
That's just my theory though. It's best to try many settings and see what feels best.
Also 2 tips if you are sailing in strong winds and areoverpowered:
1. Tighten the outhaul.
2. Lower your boom.
When moving the mast base further in front, do you feel your body position is still good?
Moving my mast foot forward 40mm from the back third to the middle has been a game changer for me when using my 4m sail in +15kts and largish wind swell. Prior to the move I was breaching on the wave face when wave riding.
Select to expand quoteLechatMB said..
When moving the mast base further in front, do you feel your body position is still good?
Depends on body size/geometry relative to all the board adjustments. For Example: I'm a smaller guy 5'8". Using the most forward foot strap position, the farthest I can have my UJ forward is about 3" from the rear of the mast track. Any further forward and I cant get balanced in the Harness. It's a killer on the lower back trying to lean forward enough to fly level. Took me a while to get all the options sorted out for balance. The more balanced, the longer I can ride.
Select to expand quoteLechatMB said..
For you windfoilers out there, I'm riding a slingshot wizard v3 130l with a ptm926 phantasm foil with a 5,7 or 6,7 sail for light winds and feel really balance. When I change for smaller sails in higher wind, the board is harder to control and I have more front foot pressure. Do you change the mast position more in front or maybe get the foil more in back of the board in this condition?
That's when you get a smaller front wing 
Otherwise if you keep the same foil, I'd move the mast base forward (for me max 2cm).
Getting your harness lines much longer if you have adjustable one will help you getting the rig forward and increase the mast foot pressure as well. Then you can also move the boom lower but again within reasons (for example, I moved mine between shoulder high to eyes high).
Flatening the sail at the outhaul will give you better control but if you do it too much, it will also unload the nose of the board when you go downwind so it's not always an option if you have to bear away or if you're doing downwinds.
I'm not familiar with moving the foil fore and aft as I use Tuttle box but I'm assuming that should decrease the front foot pressure if you move it back.
There is also the option of reducing the angle of the stab but that will decrease your longitudinal stability if you reduced it too much as well.
Best to try and see which combinations of all this works best, knowing that each parameter will affect another one of course 
Select to expand quoteLechatMB said..
For you windfoilers out there, I'm riding a slingshot wizard v3 130l with a ptm926 phantasm foil with a 5,7 or 6,7 sail for light winds and feel really balance. When I change for smaller sails in higher wind, the board is harder to control and I have more front foot pressure. Do you change the mast position more in front or maybe get the foil more in back of the board in this condition?
No. Always the same mast/foil position in my case.
Same board and foil settings for 7.0 as well as 3.5. I did exactly this a couple weeks ago out in the east gorge. Morning 7.0, afternoon 3.5, all on one board and one foil.
Body weight does not change unless I eat a lot (or fast a lot). Front foot-back foot unchanged also.
