Forums > Stand Up Paddle Foiling

Ventral fin for DW foilboard

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Created by mikesids 1 month ago, 8 Apr 2019
mikesids
17 posts
8 Apr 2019 7:07AM
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HI,
Am considering getting a custom DW / soft wave board made , thinking of having a bevelled tail section to help with pumping. One thing I have found with short SUP foil boards is that when putting in a number of paddle strokes on the same side to try and grunt onto a soft roller the yaw effect is pronounced and the board ends up rolling onto the heelside edge and the roller is gone. When learning on a converted wave SUP I found using a couple of tralier fins really helped counter this yaw . If I have a large tail bevel on my custom board that will remove the possibility of having a trailer fin.

I see that with some of the very short boards the riders have added a ventral fin - I have most commonly seen this in the Kalama boards. Does anyone have any experience with ventral fins , how do they compare with trailer fins ?

Just before anyone replies with " no need for a ventral fin, just sprint paddle and pump the foil up , you should be on a 6 foot board" I am 55 and my days of sustained sprint paddling are well behind me ! I am just wanting a board that has extremely good directional paddle power and stability so I can get more waves / rollers when conditions are a bit soft and gutless , and to play around with downwinding. I want to get more paddle strokes per side than I get currently. I am not talking about catching formed waves with good power, I have that part sorted.

Thanks in advance

Seajuice
NSW, 400 posts
8 Apr 2019 10:15AM
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Hi mikesids. I haven't downwinded as yet. But of course a fin would help. But how much? Only you will find out because everyones technique & power is different.
Another option to look into is the V nose shaped boards like the big down wind SUP shapes. But of course in a short length. I'm sure they would track straighter.
But I am unsure if they have been tried, proven or recommended as yet.

paul.j
QLD, 2802 posts
9 Apr 2019 8:55AM
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mikesids said..
HI,
Am considering getting a custom DW / soft wave board made , thinking of having a bevelled tail section to help with pumping. One thing I have found with short SUP foil boards is that when putting in a number of paddle strokes on the same side to try and grunt onto a soft roller the yaw effect is pronounced and the board ends up rolling onto the heelside edge and the roller is gone. When learning on a converted wave SUP I found using a couple of tralier fins really helped counter this yaw . If I have a large tail bevel on my custom board that will remove the possibility of having a trailer fin.

I see that with some of the very short boards the riders have added a ventral fin - I have most commonly seen this in the Kalama boards. Does anyone have any experience with ventral fins , how do they compare with trailer fins ?

Just before anyone replies with " no need for a ventral fin, just sprint paddle and pump the foil up , you should be on a 6 foot board" I am 55 and my days of sustained sprint paddling are well behind me ! I am just wanting a board that has extremely good directional paddle power and stability so I can get more waves / rollers when conditions are a bit soft and gutless , and to play around with downwinding. I want to get more paddle strokes per side than I get currently. I am not talking about catching formed waves with good power, I have that part sorted.

Thanks in advance




The thing that is better than any fin is technique and this alone will make the biggest difference with going straight. I use a 5'5 and have zero issues with it and if you are wanting to DW then timing and technique will be far better to work on the a center fin. Not saying don't use one but i do feel they are not really needed in most cases.
By the way if you want to DW you will have to put in bit of a sprint otherwise you will be doing alot of long slow paddles on a very small board but just keep in mind if you get the timing right it should only be 4 to 6 hard strokes and you will be up.

We made a board with some big concaves and yes it did keep the board a bit straighter but the down sides were it became a bit sticker to get of the water and when touching down it just did not pop back up as nice as our nice flat bottom boards. I do feel maybe the fin could catch some times but maybe some one who has tried it could be more help with this?

So for me timing and technique are number 1 and still riding a board as short as you can go while still feeling good, going a little wider rather than longer is better as well and if your board is to narrow you can not get good power strokes in and when we are talking about only 4 to 6 good strokes and everyone counts stability is really your friend.

scubaste
WA, 168 posts
9 Apr 2019 10:01AM
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mikesids said..
HI,
Am considering getting a custom DW / soft wave board made , thinking of having a bevelled tail section to help with pumping. One thing I have found with short SUP foil boards is that when putting in a number of paddle strokes on the same side to try and grunt onto a soft roller the yaw effect is pronounced and the board ends up rolling onto the heelside edge and the roller is gone. When learning on a converted wave SUP I found using a couple of tralier fins really helped counter this yaw . If I have a large tail bevel on my custom board that will remove the possibility of having a trailer fin.

I see that with some of the very short boards the riders have added a ventral fin - I have most commonly seen this in the Kalama boards. Does anyone have any experience with ventral fins , how do they compare with trailer fins ?

Just before anyone replies with " no need for a ventral fin, just sprint paddle and pump the foil up , you should be on a 6 foot board" I am 55 and my days of sustained sprint paddling are well behind me ! I am just wanting a board that has extremely good directional paddle power and stability so I can get more waves / rollers when conditions are a bit soft and gutless , and to play around with downwinding. I want to get more paddle strokes per side than I get currently. I am not talking about catching formed waves with good power, I have that part sorted.

Thanks in advance


Hi Mikesids
What I have found on my foil journey, is that if the foil is dragging the board will turn,row,yaw pretty badly.
Try shimming the foil so it sits a bit more parallel to the deck when paddling, you might find she's pointing down when you stand on the board, which will create drag, the board has no alternative but to turn...??

mikesids
17 posts
9 Apr 2019 3:07PM
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Thanks for your input guys. In particular @paul.j, appreciate your feedback , you are well down the track compared to the rest of us. Part of my motivation to optimise my gear is that the last three sessions i have been out at various locations with bars where a wave will almost form , crest a little , then flatten down as it heads towards shore. Getting two or three rides over a two hour session after a 1-2 hour drive is a p*ss-poor return for effort invested in my opinion !!!

If you can get up though you can get some quite long rides so its all about getting up on the foil for me . I have the M200 so there's not to much bigger I can go , and don't want to use a M280 in anything that could become a breaking wave. Like you say Paul, it is about those magic 4-6 power strokes , and not having the board yaw too much. If you are really grunting it then you can definitely induce yaw which is hopeless. So I am looking to see if there might be solutions to help me harness more of this paddling effort, but I do accept that good technique and fitness helps a great deal also.

Cheers

Seajuice
NSW, 400 posts
9 Apr 2019 7:33PM
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Hi Mikesids,
Regarding paddle technique. Have a look at what Colas has said in the General paddleboarding section Mastering lateral balance on small SUPS. Colas explains the right stance on getting on waves earlier in that exact stance that he explains. It may help.
Something I will be practising next on not only my foilboard but also my smaller SUP.
In short it is feet offset & close & parallel to centre stringer of board. Back leg knee lowered & weight adjustment of front foot which helps body weight forward or back & board nose height to get the fastest glide & more powerful paddle stroke.

colas
3148 posts
9 Apr 2019 8:35PM
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mikesids said..
If you are really grunting it then you can definitely induce yaw which is hopeless.



No, you can apply as much strength as you can if the force vector you apply to the paddle goes through your foil mast: it acts as the "nail" as I explained in:
www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/Tips-for-straighter-paddling#1604649
(also the vertical shaft helps immensely)

Compared to a SUP takeoff, for a foil takeoff you want to give bursts of speed to the foil wing so it can reach its critical speed, even for a split second, and trigger the liftoff. Good foilers do it by rocking the board, but if you haven't yet mastered it (it requires some balance and timing), or are on a 1rst generation board (no whistle tail) a good substitute is to "lock" your whole crouched body so that the hard pull on the paddle by your whole body is directly transmitted to the board, making it lurch forward and giving the foil wing a sudden boost of speed.

Fishdude
48 posts
11 Apr 2019 8:39AM
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Kings paddle sport latest foil board has a spot for a fin in the tail. They mentioned putting a 7 inch fin in. Anglefoils setup. If it were me it would be a soft Proteck flex fin.
picdeer.com/kingspaddlesports

colas
3148 posts
11 Apr 2019 3:03PM
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Fishdude said..
If it were me it would be a soft Proteck flex fin.


I use cheap soft plastic keels (sold for beginner boards), that I cut to 2" depth and sanded, keeping blunt edges.

The low depth mean they are always out of the water when flying, and the wide base that they are very efficient at low speeds, for the paddling and take off phases.

Tip: sanding a fin is incredibly easier if you tie the sander/drill in place and move the fin on the sanding disk by hand, and use low/medium disk spin speeds, instead of clamping the fin in a vice and handling the sander. I don't know why.

Soft river keel fins should be great also, such as:
www.surffcs.eu/products/fcs-ii-sup-river-keel-sup-fin



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"Ventral fin for DW foilboard" started by mikesids