Where to top out a quiver?

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Where to top out a quiver?

Postby Shawn Henderson » Mon Jun 29, 2009 4:56 pm

I don’t speak math real good, so this may be off base or missing something, So I need to ask...

"Force on a sail is proportional to the square of the wind velocity" I found that one on the internet so it must be accurate. :roll:
So if I understand correctly what that means is if the wind halves from 20 to 10, the force on a sail will Decrease by four times (25% force is all you get)
This curve makes me think you get diminishing returns on your sail size to wind speed.
At some point a larger sail would become more cumbersome to use while offering diminishing benefits. A lower top speed = less fun in the best case, with the potential of not getting to plane any more then before spending big $ on a new sail, boom and mast. (Unless I also buy a special formula board :?? .)
Assuming I am at least partially correct. It would be better to sit it out and concede a skunk at some point, but at what sail size? I need to find the top of my quiver without wasting money I could spend on a board, or update to my existing sails. Any help? I am gun shy on this purchase. 7.5 is my biggest sail and it has not been quite enough to plane at times. Thanks, Shawn
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Re: Where to top out a quiver?

Postby Leo Chan » Mon Jun 29, 2009 5:53 pm

Shawn, I think you got it right. The bigger rig will require huge investment. If you go from a size of 5.5 to 7.0, that's 25% increase in sail size. So, the new power generated by the 7.0 is 1.25^2 the power of the 5.5. Going from 8.0 to 9.5, you get less than 20% increase in sail surface, an increase of 44% power, much less than the same size increase from stepping up to 7.0 from the 5.5. However, at certain wind speed, only sail of certain size can get you going. When I got my 8.0 in 2007, my planning time increased by 20% because the wind speed required to plan dropped from 18 mph to about 15 mph. Delaware has a lot of 15 mph day in the summer.

So, depends on your desire, if you want to really enjoy the summer days in Utah, you need a formula board and formula rig. Else, do what the other do: go west!

I am going east. :)
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Re: Where to top out a quiver?

Postby Craig Goudie » Mon Jun 29, 2009 9:28 pm

Hi Shawn

Your V squared equation is correct. But look at it this way, it means you can space
your huge sails out over a much greater span. For example, you could go 9.0, 7.5,
6.5. That said, a huge rig is going to cost, and you can either pay the cost, or
not plane, you get to choose. With a 9.0 you'll want a huge carbon boom, which
will be about $500, and a 100% carbon SDM 520 mast which will retail for about $500
(but I've got a brand new one I'll sell for a lot less than that, as my unusually stubby 9.0 rigs on a 490). You're going to need a fairly
wide board (say about 80 cm minimum), with a huge fin also, to make that work.
The nice thing about huge gear is that it's mostly a racerhead thing and they turn
their gear over every year, at a typical 50% reduction, so used gear can be a real bargain in a low wind quiver.

My 9.0 gets my 180 lbs planing in about 10MPH. The real experts on this are Carl Christensen, and
Sarah Ranes, maybe one of them will chime in here. Due to friction (sailors call it drag),
a bigger sail than 9M is not going to get you planing earlier than a 9, The lower limit in wind
speed is about 8MPH as a planing threshold (for a light guy who knows how to pump).

BTW, I'm currently dropping from my 9.0 to my 6.5, it's doable, but just barely.

-Craig



Shawn Henderson wrote:I don’t speak math real good, so this may be off base or missing something, So I need to ask...

"Force on a sail is proportional to the square of the wind velocity" I found that one on the internet so it must be accurate. :roll:
So if I understand correctly what that means is if the wind halves from 20 to 10, the force on a sail will Decrease by four times (25% force is all you get)
This curve makes me think you get diminishing returns on your sail size to wind speed.
At some point a larger sail would become more cumbersome to use while offering diminishing benefits. A lower top speed = less fun in the best case, with the potential of not getting to plane any more then before spending big $ on a new sail, boom and mast. (Unless I also buy a special formula board :?? .)
Assuming I am at least partially correct. It would be better to sit it out and concede a skunk at some point, but at what sail size? I need to find the top of my quiver without wasting money I could spend on a board, or update to my existing sails. Any help? I am gun shy on this purchase. 7.5 is my biggest sail and it has not been quite enough to plane at times. Thanks, Shawn
Craig Goudie
Sailing the high desert lakes of Utah on my:
150 Sumo, 8'6"RRD TT, 8'2"Cross M
with Sailworks/Naish Sails

Sailing the Gorge on my:
9'1"RRD Freeride, 7'9" Open Ocean Slasher, 8'0"Hitech
with Northwave Sails
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Re: Where to top out a quiver?

Postby Leo Chan » Mon Jun 29, 2009 11:14 pm

Oh, I just found this article by Jim Drake:
http://www.star-board.com/images/2007/d ... ecture.pdf
It should answer most of the puzzles. :mrgreen:

If you're truly into the physics of it:
http://www.star-board.com/images/2007/d ... Forces.pdf

:88

This is an old article in Windsurfing Magazine that talks in detail about stance:

http://www.star-board.com/images/2007/d ... ALANCE.doc

Image

Image

Image

Image

Image

Image

Image


:88 :88

All of the above can be found here: http://www.star-board.com/drake_chronicles.php

The bigger gears are heavier and create more drag forces. So, you can do couple of things if you want to plane early:

1. Get lighter and wider board and loss weight.

2. Get bigger sail or special sail that is designed to have more pull.

BTW, if you have not try formula board, I highly suggest you to give it a try. There is nothing more enjoyable than flying across a glassy water surface!
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Big Rig

Postby Shawn Henderson » Tue Jun 30, 2009 12:04 am

Ouch my brain hurts just looking at the pictures. that cant be good. but Great info, thanks. :-P I think I will look for a 9.0 It sounds like a sweet spot for casual planning. Enough size to make a difference, but not too big to become ridiculous. If I cannot plane on a 9.0 then I will have to concede being skunked. perhaps I am all set on the mast and board. I picked up a Powerex speed 490 at the swap for my 7.5 Retro (460 RDM was not giving me enough downhaul.) And I also sail on a free formula 138L 80” wide. If I can find a 9.0 stubby sail similar to the one you mentioned Craig, maybe it would all work out. With the exception of the carbon boom ouch again! So what would the carbon vs. aluminum do? Swing weight on sail flips? Stiffness? I already splurged on the 100% mast because I was told with the larger sails, weight becomes more of a factor. But so does the price. At $500+ its tempting to go cheap. Especially when the weight difference on aluminum is not huge, but I don’t want a miserable rig either.
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Re: Where to top out a quiver?

Postby JimSouthwick » Tue Jun 30, 2009 7:44 am

1.) You're doing the right thing; if you want to windsurf in Utah, you really need to own some big gear. Even though I only weigh about 60KG, there are a significant number of days when having a 9.5 is the difference between planing and getting skunked.

2.) Carbon booms are nice but, IMHO, not essential, even with huge sails. Chinook makes a 213-274 cm boom that should work just fine with any 9m sail, and it only costs $217: http://www.bigwinds.com/wind/category/4/product/441
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Re: Big Rig

Postby Leo Chan » Tue Jun 30, 2009 8:27 am

Shawn Henderson wrote:Ouch my brain hurts just looking at the pictures.


You need to click on the articles and read the articles with the pictures. :88

Jim is right about carbon boom. Unless you want race, there is no need for that.
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Re: Big Rig

Postby Craig Goudie » Tue Jun 30, 2009 9:01 am

Since you're already a Sailworks guy, the Sailworks Retro 9.0 (what I own)is designed to work with
a 490 and a long Chinook base extension. I can only comment on my own experience with
carbon, and as a "heavy weight" (this is the only sport in the world where 180 lbs is considered
heavy), I can definitely feel the draft move around on an aluminum boom with my 9.0. That's
because heavier guys can really load up a long aluminum boon with a big sail, the boom distorts
(gets shorter), and the draft moves back as the wind gust up, and then forward again as it lulls
out. It's easy enough to deal with if the wind is steady, but if it's gusty at all your sail develops
a real Jekyll and Hyde feel you don't get with the stiffness of carbon
, and range is diminished substantially as well. Small guys can get
away without carbon, because they just can't load up a rig like us porkers. If I only sailed
in Utah, and all I could afford was aluminum, I'd still get a 9.0, and take the occasional slam.

Your board should be sweet with a 9.0 and a 60-70 cm Skeg. I know Gear Queen Linda Schlappy
was selling a used 9.1, and she still has it, but I don't know what mast size it takes. Windwing
also had brand new Gulftech carbons in formula size at the swap for $350 (might have been $300),
maybe you could get in touch with them. I'm sure somebody up here would ferry it back for you.

This whole conversation almost sounds like Martian from up here. ;*)

-Craig

Shawn Henderson wrote:Ouch my brain hurts just looking at the pictures. that cant be good. but Great info, thanks. :-P I think I will look for a 9.0 It sounds like a sweet spot for casual planning. Enough size to make a difference, but not too big to become ridiculous. If I cannot plane on a 9.0 then I will have to concede being skunked. perhaps I am all set on the mast and board. I picked up a Powerex speed 490 at the swap for my 7.5 Retro (460 RDM was not giving me enough downhaul.) And I also sail on a free formula 138L 80” wide. If I can find a 9.0 stubby sail similar to the one you mentioned Craig, maybe it would all work out. With the exception of the carbon boom ouch again! So what would the carbon vs. aluminum do? Swing weight on sail flips? Stiffness? I already splurged on the 100% mast because I was told with the larger sails, weight becomes more of a factor. But so does the price. At $500+ its tempting to go cheap. Especially when the weight difference on aluminum is not huge, but I don’t want a miserable rig either.
Craig Goudie
Sailing the high desert lakes of Utah on my:
150 Sumo, 8'6"RRD TT, 8'2"Cross M
with Sailworks/Naish Sails

Sailing the Gorge on my:
9'1"RRD Freeride, 7'9" Open Ocean Slasher, 8'0"Hitech
with Northwave Sails
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Re: Where to top out a quiver?

Postby Josh Shirley » Tue Jun 30, 2009 9:14 am

I think one other thing to note about jumping up in sail size is the type of sailing you end up doing. I jump from 6.3 to 8.0. My 8.0 is a work out. It takes a lot of fin pressure and goes fairly fast. At the end of the 8.0 session my legs are worked over.

I think that once you go big the type of sailing changes quite a bit. I hardly ever bother to water start my 8.0, it takes too much time and effort. I plan on trying to cover ground (upwind & downwind) versus practicing turns.

Bigger sail/board experience is more like sailing, small gear is more like surfing/playing.

You should be able to squeeze a lot out of your 7.5 too.
Whatever thou art, do well thy part.
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Re: Big Rig

Postby Leo Chan » Tue Jun 30, 2009 9:45 am

Craig Goudie wrote:
This whole conversation almost sounds like Martian from up here. ;*)

-Craig



Bruce Peterson is known to take out an 9.0 and sail in 15 plus mph wind at the Gorge, no? The crashes aren't pretty though. :mrgreen:

When you're ready to part with your 9.0 retro, let me know. ;))

~Leo
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Re: Where to top out a quiver?

Postby jason morton » Tue Jun 30, 2009 11:10 am

Shawn-
I would definately go with the carbon boom. No comparison. I have a brand new Powerex GS boom for sale for $550. I will let it go for $450. I am going to the Gorge thurs. night for ten days. YOU NEED IT!!!
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Re: Where to top out a quiver?

Postby Josh Shirley » Tue Jun 30, 2009 1:09 pm

Hey Jason, I will take your boom in trade for some windsurfing lessons. Humm?
Whatever thou art, do well thy part.
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Re: Where to top out a quiver?

Postby jason morton » Tue Jun 30, 2009 3:38 pm

Josh-
It's been so long since I've sailed I probably need lessons. I'll think about it.
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Re: Where to top out a quiver?

Postby Kenny » Tue Jun 30, 2009 3:42 pm

Another option is a big kite. I can plane in 8 mph winds on a 164 x 50 cm board (Spleene Monster Door) and a 19M foil kite. The nice part is that the jumps are decent when a 14 mph gust rolls by and spectacular with a 18 mph gust. I drop the board size down to a 138 x 42 when the wind is 12 mph or better.
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Re: Where to top out a quiver?

Postby Mike Egan » Tue Jun 30, 2009 9:40 pm

I have a 7.5, 9.0 and 10 retro. I used an alumium boom for years before going carbon. The aluminum boom looked like it was going to break with the 10 while sailing. 9.0 not so much. I would go with the biggest aluminum you can find if you want to save some cash. Plus, it will be stiffer if its not at max extention. Go carbon if money is no object. Formula boards are alot of work to get going, but once going they don't stop. It takes less energy to get my freeride board going in the same wind, but the formula goes through the lulls and up and down wind like a power boat. 9.0 feels small on the formula, 10 feels great. The mast will make a big difference in how much low end power you get out of your sail. I use a 75% on my 9.0 and 100% race mast on the 10. Both have the about same bottom end power but the 10 has more top end range.
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