Anyone shimming mast plate ? Pros and cons ?

Yep the reason is .
l am using a small wing foilboard to prone foil. The shims give me a better angle of attack when lying prone on the wing board as it is usually used in a kneeling position for take off. Working great 3 deg.

One of the best wingers over here in wa runs 4 degrees

I've been running 1 degree (thick end forward) for a while now, keeps nose up a bit which helps when going fast to avoid touch downs. Good for jumping and wave riding too for the same reason. Down side is it makes getting up on foil a bit harder. Sounds like I need to try a bigger shim angle.

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Relapse said..
I've been running 1 degree (thick end forward) for a while now, keeps nose up a bit which helps when going fast to avoid touch downs. Good for jumping and wave riding too for the same reason. Down side is it makes getting up on foil a bit harder. Sounds like I need to try a bigger shim angle.

Can you post pics of your setup? Could the need for shimming the mast be board specific? I am using a prone board for wing foiling and never felt a need for a shim. Gets going easy, does not get stuck when touching down.

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Taavi said..

Relapse said..
I've been running 1 degree (thick end forward) for a while now, keeps nose up a bit which helps when going fast to avoid touch downs. Good for jumping and wave riding too for the same reason. Down side is it makes getting up on foil a bit harder. Sounds like I need to try a bigger shim angle.

Can you post pics of your setup? Could the need for shimming the mast be board specific? I am using a prone board for wing foiling and never felt a need for a shim. Gets going easy, does not get stuck when touching down.

Absolutely board&foil combo specific.
You might need nothing, thick end fwd or thick end rear and different degrees.

Shimming is most often implemented to accommodate incompatibilities between board and foil, meaning either (a) the board has rocker in the tail and the foil was built for a flat tail, or (b) the foil was built for a board with rocker and the board is flat. If the board doesn't have tail rocker and the foil is intended for a board with a flat tail, then you shouldn't need to shim the mast for it to work as intended.

That being said, a mast shim is also a way to isolate lift / weight balance independent of where the foil sits in the tracks. A foil turns differently depending on whether it is further forward (more pivot) vs further back (more locked), but position in the tracks also impacts lift and weight balance. If someone were to move their mast all the way forward, they might like how it turns, but may not like the added lift or front foot pressure. In this instance, they could shim the front of the mast plate to produce less lift, while keeping the mast at the front of the track.

Between shimming the base plate, moving the mast in the tracks, changing the fuse length and shimming the tail, you can easily spend more time fidgeting than riding... not my bag.

I have had a couple of boards ride nose down , which is a feeling I hate. Touchdowns are a lot heavier when the nose rides down as the board really seems to stick more and throw you off. With my current one that does this I just use the PPC plate shim ( thick part forward), it really helps even up the foot pressure and raise the nose more - it's an easy fix. You might need slightly longer bolts at front of plate is the only thing to be aware of , in order to get sufficient thread engagement.

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Taavi said..

Relapse said..
I've been running 1 degree (thick end forward) for a while now, keeps nose up a bit which helps when going fast to avoid touch downs. Good for jumping and wave riding too for the same reason. Down side is it makes getting up on foil a bit harder. Sounds like I need to try a bigger shim angle.

Can you post pics of your setup? Could the need for shimming the mast be board specific? I am using a prone board for wing foiling and never felt a need for a shim. Gets going easy, does not get stuck when touching down.

I shim to keep the nose up/nose level when going fast winging, a taller mast would keep the nose off the water too. I'm on an 80cm mast which doesn't help. Just cruising around it wasn't an issue but once you start chasing Slalom sailors every little bit helps. Moving the mast forward brings the nose up but means you can't keep as much front foot pressure down at speed as your weight has been shifted back. Mast shims are cheap, try one.

A light weight lady I foil with shims thick end back, says it helps get her up on foil easier and likes the feel. Every board, foil and rider is different, what ever works for you.

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stroppo said..
One of the best wingers over here in wa runs 4 degrees

Well that was interesting, after reading this I printed up a 2 degree shim and it's works better for me than the 1 degree. Strange thing is it actually felt like it got up on foil easier which doesn't seem to make sense. Might try 3 next

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Velocicraptor said..
If someone were to move their mast all the way forward, they might like how it turns, but may not like the added lift or front foot pressure. In this instance, they could shim the front of the mast plate to produce less lift, while keeping the mast at the front of the track.

Interesting...or not because I thought it was clear in my head with all the testing what I felt...now you putting all sort of ?? in my "ressenti". ;-) I was under the impression by shimming front / back mast plate, I can change the angle of attack of the foil while board is flat on water(Help for take off or not by sinking the nose) or help/not help for touch downs. However as soon as i foil, it doesn't make an impact on foot pressure? For turning, I should double check that, I wasn't sure by having my mast fwd with a lot of loading on my front foot it was turning better or banking better? I think I felt the yaw enhance maybe not sure, but I felt shimming the stab was making better banking turns...when you push on back foot?You made me want to revisit all those parameter...I wonder now should I shim or should I move mast lol.

I had my foil all the way forward in my tracks for a long time and every thing felt Okay. I got a Foildrive plus the other day and noticed it was difficult to get on foil as a efoil. Because your not suppose to pump the board, just use the board speed to get up in flat water... I ended up putting a straight edge (a non tapered paddle handle) on the foil box. It turned out the box had some tail rocker in it. The straight edge was further away from the board than it should have been, by maybe 3-4cm. It's a little subjective because of the nose rocker. A few shims later,( thick end back), and presto! Now I can use more of the range of the foil box and things feel better. It gets up easier as a efoil and winging. I suspect shimming the box more parallel to the board could be especially helpful for getting up in light wind conditions.

Here's an untested theory of mine from a prone surf point of view......a high nose, ie shim thick end forward helps with pumping with a short mast or choppy conditions, and steep takeoffs. But according to Eric Antonson progression project this fwd shim actually hinders pumping efficiency, and, as my pumping improves I tend to agree. I think effective pumping relies on our bodies leaning forward in relation to the foil. If I shim my mast so the nose is up, I'm effectively leaning back more. My hunch is that rather than shimming the mast, a hollow for the front foot in the deck would encourage the forward lean without stuffing around with shims. Should we actually be shimming ourselves (our feet) in relation to the foil so that we lean forward more aggressively without altering the attitude of the board in relation to the water? Perhaps a chunk of foam under our back foot? My next home mader will have a front foot recess.....

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mojoflex said..
Here's an untested theory of mine from a prone surf point of view......a high nose, ie shim thick end forward helps with pumping with a short mast or choppy conditions, and steep takeoffs. But according to Eric Antonson progression project this fwd shim actually hinders pumping efficiency, and, as my pumping improves I tend to agree. I think effective pumping relies on our bodies leaning forward in relation to the foil. If I shim my mast so the nose is up, I'm effectively leaning back more. My hunch is that rather than shimming the mast, a hollow for the front foot in the deck would encourage the forward lean without stuffing around with shims. Should we actually be shimming ourselves (our feet) in relation to the foil so that we lean forward more aggressively without altering the attitude of the board in relation to the water? Perhaps a chunk of foam under our back foot? My next home mader will have a front foot recess.....

I think your idea is good!.
If you want to keep the takeoff behaviour "as it is" but want a more nose down board when in flight then putting a thicker tailpad will do the job.

A front foot recess should do the same,as long as it does not bother you when paddling prone.

From the good folks at Appletree Surfboards:

Negative Angle, Positive Feeling! The biggest innovation for the Pro-Foil is the new recessed deck with a slight negative angle of attack. We know this sounds strange, but hear us out! Firstly, the recessed deck is amazing for paddling as it 'hugs' your chest, allowing more control and power in your paddle. Once you have tried it, you will never go back to flat decks. The main benefit of the recess is we can now play with the attack angles of the board. A board with a bit of rocker in the bottom helps for better touchdown performance and easier takeoffs as it deflects the water down your board, and the rider upwards. This is the way you want to go, but the negative impact is your standing area on the deck will have an upward angle. This increases back foot pressure and is not good for foil control and makes pumping the board much harder. With the recessed deck we can increase the bottom rocker while keeping the standing area at 90 degrees to the foil tracks, but the fun doesn't stop there. We can now also tune the angle of attack, and after numerous experiments, we have found that a slight negative angle vastly improves both the pump and the ride feel on a wave. The Pro-Foil V2 has a -0.3 degree negative angle between the standing area and the foil mast.

appletreesurfboards.com/product/pro-foil-surf-v2-allround-surf-foil-board/#stock-or-custom

so many factors make a perfect setup of course.I think the mast shim most importantly comes into play mostly at the moment of transition from planing to flying. Secondarily, it will effect the feel while flying - but in my opinion it would be a lot better (if it were possible) to sculpt the deck for this feel rather than angle the mast.

If the board has tail rocker and the foil is consequently angled down because of this - then in order to get the foil to fly you have to be "plowing" the planing surface of the board through the water. It is very noticeably harder to get the board out of the water. Add shim under the tail end of the mast plate.
If the foil has too much angle of attack when the board is coming up to planing - then it'll lift and grab before we get all the way up to speed. And this often results in slamming back down because there just isn't enough speed to fly the foil right. Add shims to the front end of the mast plate.
Mental model here is to think about the board with no foil under it - how should it sit in the water and plane/surf most efficiently. Then add the foil at the correct angle so it adds smooth amount of lift as you get just above planing speed.

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mcrt said..

mojoflex said..
Here's an untested theory of mine from a prone surf point of view......a high nose, ie shim thick end forward helps with pumping with a short mast or choppy conditions, and steep takeoffs. But according to Eric Antonson progression project this fwd shim actually hinders pumping efficiency, and, as my pumping improves I tend to agree. I think effective pumping relies on our bodies leaning forward in relation to the foil. If I shim my mast so the nose is up, I'm effectively leaning back more. My hunch is that rather than shimming the mast, a hollow for the front foot in the deck would encourage the forward lean without stuffing around with shims. Should we actually be shimming ourselves (our feet) in relation to the foil so that we lean forward more aggressively without altering the attitude of the board in relation to the water? Perhaps a chunk of foam under our back foot? My next home mader will have a front foot recess.....

I think your idea is good!.
If you want to keep the takeoff behaviour "as it is" but want a more nose down board when in flight then putting a thicker tailpad will do the job.

A front foot recess should do the same,as long as it does not bother you when paddling prone.

Thanks mcrt.....got me thinking after posting some sort of tail pad adjustment like the Armstrong boards have, only up and down as well as front to back. There would have to be some variability with conditions or styles of riding, but starting with a small foot recess (1/2") and working from there is in my mind. I agree with appletree mob re the chest grip of a concave deck too. Also utilizes the properties of carbon better, hopefully allowing for less materiels in the deck.
I'm sure this crosses over to winging, I spend all my time trying to drop the wing and glide or pump....