Forums > Stand Up Paddle Foiling

Foil Volume = + / - board stability ?:-)

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Created by Johndesu Two weeks ago, 5 Sep 2020
Johndesu
NSW, 265 posts
5 Sep 2020 11:15PM
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Howdy
A question for the smart cookies out there -
Just wondering how much volume (if any) is added to a foil board once it is in the water? and also would the board now be more stable or less stable (compared to say a regular quad or thruster fin set-up on the same board)?
thanks :-)

Pacey
WA, 288 posts
5 Sep 2020 10:08PM
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You are adding volume, but you are also adding weight, so the effect on buoyancy is going to be pretty neutral unless the foil is very heavy or very light. Effect on stability at rest due to buoyant or weight related forces will be pretty neutral unless the foil is heavy, in which case it will stabilise the board slightly; or light, in which case the buoyancy of the foil will destabilise the board slightly.

however the lateral area of the mast will resist roll quite a lot, so the board will feel more stable when you are standing on it compared to if you only had a short fins in it

tomooh
207 posts
6 Sep 2020 3:30AM
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Certainly the front wing size makes a huge difference to stability. I have a 1600 and 1200 size foil and find paddling around on the 1200 way more difficult and unstable. More difference than I would have thought.

Johndesu
NSW, 265 posts
8 Sep 2020 12:22AM
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Thanks Pacey & tomooh it makes sense I just need to try for myself now, also just wondering if a heavy foil (5-6kg) is better / or does it make a difference compared to a lighter foil (3-4kg) for all round surf foiling etc?:-)

tomooh
207 posts
8 Sep 2020 3:43AM
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There is all sorts of opinions about whose foils are better. I started with alloy masts fuselage etc and now have Armstrong carbon. Its nice to have a light rig that is well made and looks like it will last. But if you are starting out a cheap second hand set up works fine and can be resold whenever you want to upgrade. I think it is more about the area underwater than the weight that affects stability and its nice to have a board that is not a constant struggle to stand on and paddle.
b

Johndesu
NSW, 265 posts
9 Sep 2020 10:59AM
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Yes I see tomooh but I recently bought a second hand Ride Engine foli with a massive front wing 84 (5.5kg) and it looks great + I also bought a second hand board Sunova 7.8 sling shot (7.5kg) but together it is just all too much / too heavy for me to carry to the surf and back so I won't be able to take it out to try even.
thanks

Pacey
WA, 288 posts
9 Sep 2020 9:46AM
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Johndesu said..
Yes I see tomooh but I recently bought a second hand Ride Engine foli with a massive front wing 84 (5.5kg) and it looks great + I also bought a second hand board Sunova 7.8 sling shot (7.5kg) but together it is just all too much / too heavy for me to carry to the surf and back so I won't be able to take it out to try even.
thanks


I agree the Ride Engine/Slingshot foils are heavy, but they are a good foil and a good place to get started. Maybe try carrying the board and foil down separately and putting them together on the beach would be easier.

tomooh
207 posts
9 Sep 2020 5:02PM
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Or see if there is someone who is a little bit stronger than you that could manage to carry it down the beach and might buy it off you.

Johndesu
NSW, 265 posts
9 Sep 2020 11:47PM
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tomooh said..
Or see if there is someone who is a little bit stronger than you that could manage to carry it down the beach and might buy it off you.


I do not think that is possible so I think that I would need to get / buy the smallest & lightest board that I am comfortable probably between 6-7ft between 100 - 120L (my sups are 6.10 & 7.2 about 90L each) and than afterwards buy the lightest carbon foil that I can ride :-)

GranG
WA, 250 posts
Sunday , 20 Sep 2020 12:05PM
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Swapping from an axis (Al mast) to a Armstrong (Carbon mast) on the same Sunova SUP 105litre board, I could definitely feel the extra flotation. I weigh 86kg, 6ft. Also, when I fall off or the board shoots back from a wipeout wave, it does take longer to sink / go down.

Overall, I don't think it is a huge difference, but certainly in my unique set of gear, I would say the foil change added about 5 or so litres of volume to the board.

Getting back on a normal SUP though, I am all over the place with latteral stability... that big keel makes a huge difference!

tinka
QLD, 34 posts
Monday , 21 Sep 2020 6:59PM
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Johndesu said..

tomooh said..
Or see if there is someone who is a little bit stronger than you that could manage to carry it down the beach and might buy it off you.



I do not think that is possible so I think that I would need to get / buy the smallest & lightest board that I am comfortable probably between 6-7ft between 100 - 120L (my sups are 6.10 & 7.2 about 90L each) and than afterwards buy the lightest carbon foil that I can ride :-)


HI Johnseu, the sup i surf is 7' 3" and 26 3/4, 92 litres and 5.6 kg feels tippy, but my 5'5" x 26 80 litre sup and foil both Armstrong weighing about the same as my sup is much more stable.I reckon even though the foil is neutral bouyant the whole rig is more stable due to the foil wing underneath.

tinka
QLD, 34 posts
Monday , 21 Sep 2020 6:59PM
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Johndesu said..


tomooh said..
Or see if there is someone who is a little bit stronger than you that could manage to carry it down the beach and might buy it off you.




I do not think that is possible so I think that I would need to get / buy the smallest & lightest board that I am comfortable probably between 6-7ft between 100 - 120L (my sups are 6.10 & 7.2 about 90L each) and than afterwards buy the lightest carbon foil that I can ride :-)



HI Johnseu, the sup i surf is 7' 3" and 26 3/4, 92 litres and 5.6 kg feels tippy, but my 5'5" x 26 80 litre foil sup and foil both Armstrong weighing about the same as my sup is much more stable.I reckon even though the foil is neutral bouyant the whole rig is more stable due to the foil wing underneath.



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"Foil Volume = + / - board stability ?:-)" started by Johndesu