I`ve got the Slingshot wizard V4 130 l, with Phantasm PFI 730/872 Lower Package V1 + 103cm Wide alu mast
and Goya Banzai sails in 3.4, 4.2, 5.3 and Goya Nexus in 6.4 and 7.4.

Does anyone have experience with where to place the U/J - mastfoot placement for different sail sizes?

(I struggle with the 6.4 and 7.4 sizes and find it difficult to balance the board before takeoff due to less wind and large sail sizes, but if I`m going to nail this I also like to practice foiling in less wind....)

I move the u joint forward to keep nose of the board down, or if I'm breaching a lot. Move u joint back for more lift.

A bigger sail puts more weight on the mast foot, so you can move it back

you probably shouldn't need to move you sail foot that much but you likely will need to move your foil mast forward when you switch from 730 to 872

If you plan to use the 7.4 and the 3.4 with the same foil then likely would need the 3.4 about 2+ inches more forward in track. but chances are you will only use the 7.4 and 6.4 with 872 and the small ones with the 730

All other things being equal (yes, all), the bigger the sail the heavier it is, and the more down force it exerts on the mast base. You generally compensate by moving the mast base aft, but just a little. The whole idea is figure out the best overall sail down force and moment arm and keep that constant.

We all had to figure this out during formula racing days where it was important to get the best angle of the board on the water.

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segler said..
All other things being equal (yes, all), the bigger the sail the heavier it is, and the more down force it exerts on the mast base. You generally compensate by moving the mast base aft, but just a little. The whole idea is figure out the best overall sail down force and moment arm and keep that constant.

We all had to figure this out during formula racing days where it was important to get the best angle of the board on the water.

Thank you for the tip.

Would it be preferable to move the U/J or the foil backwards a little?
With the 5.3 and 4.2 sails I have for now found that 4 cm forward on the Slingshot Wizard 130L V4 seems to be a good spot. The U/J is about 4/5 to the rear on those sails.

No, if you move the foil backwards, it is similar to moving the sail mast base forward. The foil backward effect is much bigger since you are changing the balance point against the weight of your feet. If you want easier lift in light wind, then moving the foil forward will help a lot.

This all is the HUGE advantage of twin track mounts. You have a LOT of adjustability. My stuff is all deep tuttle, so sail base and footstrap positions are all I have.

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segler said..
No, if you move the foil backwards, it is similar to moving the sail mast base forward. The foil backward effect is much bigger since you are changing the balance point against the weight of your feet. If you want easier lift in light wind, then moving the foil forward will help a lot.

This all is the HUGE advantage of twin track mounts. You have a LOT of adjustability. My stuff is all deep tuttle, so sail base and footstrap positions are all I have.

Thanks again. I used to have deep tuttle foil also, so I know the feeling...

What would you recommend I move first, foil og U/J, and how much, for better lift in light wind with the Goya Nexus in 6.4 and 7.4 sails?

I have also just started playing with less downhall and outhal. For now it seems that I can easily do 10 clicks less on the Duotone Xt 2.0 jack from the recommended downhall mark on the 6.4 and 7.4 Goya sails? Am I on the right track with less dowhall and outhal?

I think you will have to experiment with this. Start with the U/J at midpoint and sail rigged to specs. Leave off the footstraps. Start with the foil at the midpoint in the tracks. Then sail it. Move the foil about 2 cm at a time fore and aft, but don't change anything else. Sail it again. Keep moving the foil fore and aft until you find what works. If the foil will not lift, move the foil forward. If the foil wants to come up and smack you in the nose all the time, move it aft. Once you have a position that works, note the position of your feet and mount your footstraps there.

Then later you can fine-tune the balance with the U/J.

For sail rigging, I recommend you just rig to the specifications and leave it there. What you are trying to do is to get the balance of the front wing. You don't do that with different sail riggings. Just make sure you have about the right size sail for the wind and rig to specs.