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Messages - jondrums

Pages: [1] 2 3 ... 26
1
Foil SUP / Re: Can We Talk Stabilizer Geometry?
« on: August 14, 2020, 11:39:33 AM »
can I take it further into la-la land?  :P

I can say with absolute certainty that installing your tail wing upside down does not work.  After I got out to the break this morning and bailed off the first two wave attempts I realized that I did exactly this.  Tried a few more waves just for science and the foil was unrideable for me.  (this was GoFoil 14.5 tail with short pedestal)

2
SoCal / Re: Hydrofoil GL180 7 19 7 21 2020
« on: August 12, 2020, 12:33:06 PM »
what happened at 1:18???

You're looking very competent on the water, nice!  That GL180 craves speed - I can tell from the angle of your board that you're in low speed lift mode.  If you can put down the pedal (front foot) and get going across the wave, it'll really get up and go.  hard to tell from the video if there was enough power in the wave to get it up to speed, perhaps not.

3
Foil SUP / Re: Can We Talk Stabilizer Geometry?
« on: August 12, 2020, 09:00:10 AM »
Going from gofoil flat stab (18N) to the new 14.5 upturned tips made a noticeable difference in railing turns.

It is my view that directional stability will come from all vertical surfaces - and related to both the projected area of the vertical surface and the distance from the turning center.  Super hard to know where the turning center is, so that's a bit of a mystery.  But I do think part of the confusion around tail profiles is because the mast is placed differently on different foil brands/setups.  If the mast is further forward with respect to the turning center, then I'm guessing people are going to really want vertical tips on the tail and vice-versa.

We have to have a mast, so it would be nice to get the directional stability from the mast we already have to have rather than rely on upturned tail tips which add drag.  That means the mast would need to be a bit further back on the fuse.  But then, directional stability will vary with depth in the water as the mast area changes dramatically.  So, hard to know if that's a good solution.

4
Foil SUP / Re: GoFoil NL 190
« on: August 12, 2020, 08:51:24 AM »
how the heck did anyone catch that so perfectly on video!  would be amazing to see the same on the NL wing if that's what you're going to try and capture Steamroller

5
Foil SUP / Re: GoFoil NL 190
« on: August 11, 2020, 04:24:26 PM »
In terms of rider/wave size - is the NL190 most similar to the GL180 and the NL220 most similar to the GL210?

6
Foil SUP / Re: GoFoil NL 190
« on: August 06, 2020, 02:33:12 PM »
starting to see more and more instagram mentions of the NL - surely someone on the board has ridden it...
paging Steamroller

7
I'm riding a 5'10"x22" 40L Dwight board very similar to this:


Really nice construction and very lightweight.  I like that it has a tuttle box for the minimum drag while paddling, but I think it could be a little bit further back - next board will definitely get boxes for adjustment.  It is also quite a dog to paddle, but that's more the 40L and my 210# than the shape. 

I'm really liking what I see out of the FCD grasshopper as a next board (the 5'6" specifically).  I'm sure some will scoff at the length and volume, but I'm all about getting into soft waves early - and I'm pumping a big old SUP board right now, so pumping this will still be super easy in comparison.  For me prone board should be all about paddle speed for getting into the wave.
http://www.fcdsurfboards.com/grasshopper-foil-surfboard

8
Foil SUP / Re: Progressing from wake foiling to downwind and winging
« on: August 03, 2020, 01:40:26 PM »
water is 70deg in Tahoe???  not my experience, but I guess you live there so you must know some spots I don't know about.

9
Foil SUP / Re: Learning to foil SUP - Riding waves
« on: August 03, 2020, 01:32:51 PM »
you don't necessarily need a longer mast.  That comes into play a lot more when trying to make tight turns and cutbacks without breaching the tips of the foil.  For flying down the line your short mast is fine - you just need to make a conscious effort to ride higher.  I am still really working on this, in fact I think I mentioned it to another board member this morning in the water - I'm trying to ride as high as I can more often.  The big benefit with riding higher out of the water is you get a huge reduction in drag.  I think it is two things: 1) less mast in the water = less wetted surface.  2) wing drag depends on the depth below the surface - the higher you are, the less water has to be lifted up and over the wing. 

I think that you'll find in order to ride higher that you need to get better at dynamically shifting your hips forward and aft for pitch control.  If you can't adjust the height above water smoothly/quickly enough, you need to ride lower in the water to avoid breaching on the overcorrections.  So my suggestion is a two-part program: 1) work on your height control via weight shifting fore-aft.  Try to make corrections quickly and ride consistently at the same height.  2) increase that height little by little.

There this little sucking sound that starts to happen when you get too high, but before you're so high you breach.  You can get used to using that for height control too.  I've found it gives you just enough warning and I can drop down a little if I make a quick correction.

10
wow!  this is really really nice build.  Your attention to detail is incredible.  Thanks for photo documenting it for us!

11
Sessions / Karma
« on: July 30, 2020, 02:58:09 PM »
I had a fairly forgettable sunrise morning out SUP foiling at my local yesterday - except for one remarkable moment.

Its a beach break, but this morning I found a peak that was breaking fairly repeatable on the sets.  This peak had just 3 other people hanging around roughly the same spot.  I'm sitting on the board relaxing waiting on a set when I notice something floating a few hundred yards further from shore - turns out to be some mostly deflated helium balloons.   So I decided to paddle out and go grab them, which I like to do whenever I see trash in the water.  I have a spot in my wetsuit that I stash trash during a session until I can bring it to shore.

So I spent a few moments sitting on my board deflating the balloons and wrapping up the ribbon to stash in my wetsuit.  Literally the moment I gathered my paddle and stood up, here comes a single massive wave that is coming right to me.  Mind you, this is more than a hundred yards outside the normal set wave takeoff zone I was harvesting.  So I spin and grab it and ride it perfectly in the pit - breaking fast right to left all the way past on the outside of the next peak over, and right through the peak after that - with everyone hooting for me.  There literally wasn't another wave even close to that size and quality in the hour before or the hour after, and it was the only one in the set.  Nobody else could have possibly been in the right place for it - and given that it was a beach break it would have been impossible to know where to be for such a wave.

I think I believe in Karma now.

12
I have been thinking for a while that there is a key difference between wind powered and wave powered foiling with respect to mast design.  For wave powered, I don't think that torsional stiffness is all that important and I expect very little angle of attack of the mast profile through the water.  For wind powered (wing or kite) I expect that the mast is used as a keel against the wind loads and therefore could have a lot of torsional loading as well as significant angle of attack through the water.  Those applications call for very different profiles.

13
Kyle - thanks for posting those blog post links - great detailed information.  It gets me excited for sure!  the 19mm chord thickness is the key to this I think.  I'm only experienced with the GoFoil mast, which is 15.5mm thickness x 140mm.  Of course the other variable is wall thickness or number of layers of layup, etc.  So my analysis above was really not taking into account reality of what you've done.  From what I see on your website, it sure looks like you've done the work

The key metric I'm after is stiffness (bending and torsional) to drag ratio.   Drag of course is going to vary with both wetted surface area as well as foil profile.  I've been thinking for a while now that a lot of the masts out there haven't nailed this yet.  To me weight is somewhat secondary - once we go from aluminum to carbon, adding a few more layers isn't going to impact the weight substantially.

14
actually we're both wrong!  I spent the last hour putting this into my structural simulation software because torsional stiffness is notoriously difficult to predict with back of the envelope and I was having second thoughts.  I found that the two below profiles are almost identical in torsional stiffness (within simulation error bounds).


this calls for some more looking so I'm going to stay up late and do some more sims tonight.  If we could reduce wetted area with the same stiffness, that'd be the ticket...

15
Contrary to what a lot of non-foilers think, I have never been hit or even touched by the leading or trailing edge of the mast.  In my opinion, flexible edges is solving a problem that doesn't exist.  Not only that, stiffness is the number one issue here.  Not extending the structural carbon all the way to leading and trailing edges will seriously limit the torsional stiffness (bending stiffness will take a minor hit as well).

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