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Stick: January 24
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dvCali



Joined: 23 Aug 2007
Posts: 1130

PostPosted: Fri Jan 24, 2020 10:31 pm    Post subject: Stick: January 24 Reply with quote

A nice late afternoon at the Stick foiling. Robert is out with the Starboard 177 + 7.8 and F4, and I am with my Flikka 117, 5.8 and the Moses. Where is everybody else?

I am still struggling with asset but is getting a bit better. Hard to tell how strong the wind is but we are very far from any white cap, maybe 10 knots or so and we are doing both quite well ... Nice! No way I could be going with a 5.8 in this conditions without a foil Very Happy
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dllee



Joined: 03 Jul 2009
Posts: 4703
Location: East Bay

PostPosted: Sat Jan 25, 2020 12:43 pm    Post subject: Reply with quote

But would you be going faster with 7.3 and 111 Isonic?
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dvCali



Joined: 23 Aug 2007
Posts: 1130

PostPosted: Sat Jan 25, 2020 9:24 pm    Post subject: Reply with quote

dllee wrote:
But would you be going faster with 7.3 and 111 Isonic?

Not really, the 7.3 would not have been enough in those conditions. Maybe an 8 but I doubt it, it was VERY light. I am now using the Moses 790 and even if my Flikka does not seem to be such an early flyer (it might be the pilot), the wing does comes up early!

(N.B. terrible mistake: this post should have been on "Where we sailed today")
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dllee



Joined: 03 Jul 2009
Posts: 4703
Location: East Bay

PostPosted: Sat Jan 25, 2020 10:29 pm    Post subject: Reply with quote

After around 58 foil days, I'm still torn on the light wind side.
Same weight as you, same 111 Isonic, but 44 cm is most often used with a handful of light wind tuned cam and non cam sails.
Yes, foiling is 6 meter vs 7.3 for slalom.
Naish foil is 1230 sq cm or so, board 73 is close to Isonic.
Still gotta plane to come up on foil, and the Isonic ready to go is 10 lbs lighter than the Naish Hover 122.
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dllee



Joined: 03 Jul 2009
Posts: 4703
Location: East Bay

PostPosted: Sat Jan 25, 2020 10:30 pm    Post subject: Reply with quote

Yes, foil goes upwind and downwind more efficiently but is easy 1-5 mph slower on a reach across the wind.
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dvCali



Joined: 23 Aug 2007
Posts: 1130

PostPosted: Sun Jan 26, 2020 12:03 pm    Post subject: Reply with quote

dllee wrote:
After around 58 foil days, I'm still torn on the light wind side.
Same weight as you, same 111 Isonic, but 44 cm is most often used with a handful of light wind tuned cam and non cam sails.
Yes, foiling is 6 meter vs 7.3 for slalom.
Naish foil is 1230 sq cm or so, board 73 is close to Isonic.
Still gotta plane to come up on foil, and the Isonic ready to go is 10 lbs lighter than the Naish Hover 122.


The Moses 790 is 1550 cm2, a thing of beauty, like all the Moses offerings.

7.3 would not have been enough, the gap for me seems to be in excess of 2 m2 in those conditions. A 8.0-8.5 with a board bigger than the Isonic 111 would have done it.

And I don't think that there is really a transition displacement, planing, foiling. There is a transition displacement, increased speed on the foil, and then the board is not touching the water. But everything happens riding the foil, there is no planing followed by foiling ...



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dllee



Joined: 03 Jul 2009
Posts: 4703
Location: East Bay

PostPosted: Sun Jan 26, 2020 1:05 pm    Post subject: Reply with quote

Read what you just said.
Doesn't make sense, does it?
Board has to plane, to unwet from displacement mode to allow higher boat speed so foil can lift the whole draggy at low speed setup.
Plus, your Isonic is 68.5 wide with a 50 tail.
So get the bigger Isonic with a bigger fin, and 1.5 meter bigger sail.....and it planes the same.
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dvCali



Joined: 23 Aug 2007
Posts: 1130

PostPosted: Sun Jan 26, 2020 2:47 pm    Post subject: Reply with quote

dllee wrote:
Read what you just said.
Doesn't make sense, does it?
Board has to plane, to unwet from displacement mode to allow higher boat speed so foil can lift the whole draggy at low speed setup.
Plus, your Isonic is 68.5 wide with a 50 tail.
So get the bigger Isonic with a bigger fin, and 1.5 meter bigger sail.....and it planes the same.


Well, maybe I am not making sense, but hydrofoiling and planing seem to be two very different things.

When you plane what happens is that water is forced downwards, by the tail of your board, and the water exercises an opposite force that lifts the windsurf.

When you hydro foil it is the foil that generates the lift force. There is of course a buoyancy component, from the hull, and there might be a planing component when the hull gains speed and starts to generate a bow wave. But the forces involved are more complex: the lift is always there, while the planing component, if at all present, eventually decreases to zero.
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kevinkan



Joined: 07 Jun 2001
Posts: 1604
Location: San Francisco

PostPosted: Sun Jan 26, 2020 3:02 pm    Post subject: Reply with quote

i think there's a distinction b/w a board coming to the surface because of it's bottom shape and planing versus unwetting due to the foil working. the large wings will fly and sustain flight at lower speeds than the board can plane or maintain a plane and it takes less power. pumping and technique further lowers the threshold (just like with planing)

some people have had a harder time learning with really big front wings because it wants to lift so early before it reaches a stable speed (analogy is a bicycle going really slow).

My front wing Slingshot Infinity 76 is ~1500cm2. the next one up 84, is about 2k

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dllee



Joined: 03 Jul 2009
Posts: 4703
Location: East Bay

PostPosted: Sun Jan 26, 2020 4:34 pm    Post subject: Reply with quote

Transition.
When displacement heads toward full foiling, BOTH the foil AND the planing hull is working.
Spent plenty of time fully planing while pumping, even rising up on foil for feets of distance, then dropping back down as pumping is lessened while looking towards front straps. The board still planing but I'm not in any straps.
That would happen mostly in 9 mph breeze with a 5.7 sized sail going into a lull.
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